HFU HF Underground
Technical Topics => Equipment => Topic started by: alpard on April 11, 2021, 2133 UTC
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What would be the best MWDX antenna?
I have been using MLA30, and it does work well sometimes when the band condition is good.
But on other nights, it is not great.
Which antenna will work best in MW and HF Low Band DXing?
What are you using for these band DXing?
Thanks
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Because of the constantly varying propagation conditions I would say that there is not any one type of antenna that is better over the other. There are multiple factors involved, horizontal or vertical polarization and skip vs. ground waves to name a few. MW stations in the 500 to 1,600 kHz band transmit vertically polarized hence the telescopic whip antenna on most AM radios. Those AM stations actually do not have any transmitting antennae per say. The tower(s) is/are the antennae. Next to having a whip, an antenna which exhibits good horizontal and vertical characteristics is the best of both worlds. This can be highly dependent on how the antenna is installed, I.E. horizontal, inverted-V, sloper etc ...
I currently use 4 x HF antennae in a fixed installation. A Barker & Williamson installed in an inverted-V fashion, a horizontal end-fed long-wire antenna which is relatively low to the ground (about 12 feet), a Wellbrook loop and a cheap clone of a miniWhip antenna. My primary antenna is the B&W with the end-fed second. As propagation changes I also change antenna. I sometimes will start to loose contact on the B&W and switch to the end-fed and the signal is back. The end-fed is also electrically quieter (less static). I primarily use the loop on beacons, down to about 20 kHz. I also use it on HF when I want to null out interference.
For portable use, I have a random length wire dipole and an AirSpy YouLoop antenna.
This summer's experiment will be an L antenna. It has the best of both worlds (horizontal and vertical).
Start with an end-fed coupled to a proper un-un matching transformer. Insert an A/B switch and you can then flip back and forth between the end-fed and the MLA loop. They both have unique characteristics.
Here is part of my antenna farm. DC to 2 GHz.
(http://www.milspec.ca/board/img/mcc-antennae-farm-2021-02-24.jpg)
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Quite agree - the propagation keeps changing, so having many different type of antennas are great advantage. Antennas are the most important factor in RXing. Even the best receivers will perform poorly with inefficient antennas.
Will try to set up End Fed wire antenna based on your recommendation. Thanks.
And I am also thinking of a vertical antenna, EWE and Flag antennas too. But vertical being omni directional, I was wondering if it will be hearing several different signals on one frequency most of the time which makes readability suffer.
EWE and Flag seem getting good reviews for MW DXing, but they are directional nulling one directions which will miss DX signals from the Nulled direction, and it is not rotatable.
Your Wellbrook looks great and I bet it works very well too especially with the rotator? What is the white pole between the Wellbrook and B&W?
I notice you have 2x Mini Whips, one on the pole, and the other under what looks like Air Conditioner box?
Great set up on the antennas. Compliments!! Your balcony looks ideal for the antennas.
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EWE and Flag seem getting good reviews for MW DXing, but they are directional nulling one directions which will miss DX signals from the Nulled direction, and it is not rotatable.
This is a feature, not a bug :)
While I agree there is no single "best" antenna for MW (or any other type of) DX, one characteristic they share is that they are directional. You want to limit reception to a particular direction, both to reject stations as well a reduce noise/static pickup from other directions. It's all about maximizing signal to noise ratio. This means that you either need to be able to rotate it (such as with a small loop, by small here I include loops up to 10 ft or so on a side, anything that you can still stick on a rotor and rotate) or have multiple fixed directional antennas (Beverage, D-KAZ, etc) each aimed in different directions. I use the latter method.
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Sure. It is also problem that the direction I want to NULL incoming signal is wide open, but where I want more signals received, there is a building blocking :)
So, it had been very tricky to find the best position of FLAG or KAZ or EWE in this property, if I were to installing one.
So, I set up 2x MLA30 one facing EW and the other NS directions.
And I have a Wellbrook Loop pointing to SE and NW.
They can be selected by the menu of the RSPdx, which allows you to install 3x antennas at once, and
change in the menu by clicking ABC.
But I have been feeling these antennas are still not good enough for RXing the trans Atlantic MW stations or
Far Eastern MW stations. Maybe MW DXing condition is poor recently?
Or do I need better receiver? I wasn't sure. But I was more inclined to be suspicious on the antennas, and
their DX signal hearing capabilities. Perhaps I need larger and more concentrated directional antennas?
I can hear pan European signal quite well over night recently with the antennas I have, but for trans Atlantic or Far Eastern
signals or from South America or Pacific, I have not heard any for ages.
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I've made one of those gods-eye antenas for MW, with a variable air CAP, and done well both indoors and out. They are, however, very bi-directional. http://167.250.5.172/docs/Radio/Antennas/Am_Loop_Antennas_2004.pdf
The other thing that can be done is to make an inductive loop coupler to the End Fed Longwire. Me??? I still want to lay down the W.O.G., (Wire On Ground.), since that's suppose to be excellent in noise reduction. Hopefully, this Fall 2021, that will happen.
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I've made one of those gods-eye antenas for MW, with a variable air CAP, and done well both indoors and out. They are, however, very bi-directional. http://167.250.5.172/docs/Radio/Antennas/Am_Loop_Antennas_2004.pdf
The other thing that can be done is to make an inductive loop coupler to the End Fed Longwire. Me??? I still want to lay down the W.O.G., (Wire On Ground.), since that's suppose to be excellent in noise reduction. Hopefully, this Fall 2021, that will happen.
Wow. Fantastic info on the Loop Antennas.
I was thinking of making one of those actually.
But always under impression indoor antennas will not be
as good as anything outdoor one. Maybe it is not always the case.
Thanks for the link for the document.
Please let us know about your W.O.G. project.
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The white pole between the loop and the Barker & Williamson (B&W) is one of the end pieces from the B&W. If you follow the wire up you will see the centre support and as you keep going toward the house another support before it goes to the balun. I'm standing about 50+ feet back from the house which distorts the picture. The B&W is like a T2FD and is setup as an inverted-V. That is somewhat around 160 feet or so of wire between both legs.
Mini-Whips, yes, you are correct. The second one is hanging from under the air conditioner and feeds my Icom IC-R75. It's my bedroom night stand radio. I'm not overly pleased with the mini-whips. They are not the original design. They are ok but the two that I have are not great performers, at least not what I expected out of them. I don't have a real PA0RDT Mini-Whip to compare them to.
I am very pleased with the Wellbrook. It is on a HAM-IV rotator, which is an overkill, but that is all I had handy at the time and I like the controller. I unfortunately do get killed by local AM stations so as a test I ordered some Nooelec Flamingo band stop filters. They just came in this afternoon so now I have something to play with. I did not want to entirely kill the AM band as I wanted to do some AM DXing with the loop but the loop has so much gain that it overloads the receiver front end and splatters. I have been operating it with a 10dB attenuator. If the Flamingos work I can then build individual notch filters and only remove the offending stations from the AM band as opposed to the entire band.
(http://www.milspec.ca/board/img/mcc-am-radio-transmitters-2021-01-31.png)
I would not worry to much about that building in your way. By design, AM broadcast station signals are engineered to travel by groundwave. Keep the antenna low to the ground.
Since you have E/W & N/S antennae, have you thought of putting one of them 180 degrees out of phase? If you want to listen to E/W you put the N/S antenna 180 degrees out of phase to null out the interference from that direction. Same principle as putting audio cables out of phase. Chris who is on this thread manufactures and sells BALUNs. Maybe he can manufacture a transformer that is 180 degrees out of phase. Now I know I just got Chris's gerbils turning because he could actually do that with his antennae as well.
I have one more antenna on the way, the new version of the RTL-SDR L Band Patch for GPS, INMARSAT and IRIDIUM. Now it is time for me to go and catch some radio waves.
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I see what you mean. The camera lens can distort the realities I suppose. :) It looked like another vertical antenna of some sort :D
I also have a R75, and it is a great radio. It works very well with my Wellbrook. I also had some problem with the Wellbrook. It was very very noisy. The problem was cured by inserting a few ferrite ring choke filters to the incoming antenna coax and also the power supply lead. It now works very nicely without any noise. On my RSPdx it can be seen well balanced and very sensitive.
It is very directional, it won't receive the signals which is not coming from where it is pointing, hence rotator is a must if one is using one antenna like this. But I cannot use rotator - so instead I set up different loops pointing different directions.
I was thinking about phasing the 2x loops. I have this T piece BNC, and thought it can be inserted with 2x coaxial cables from the 2x loop antennas. But I was not sure exactly how they work. I was under impression you need a phasing controller. Some people were using the MFJ noise canceller, and there are now a cheap Noise Canceller which look like a clone of the MFJ on eBay for about 50 bux. Not sure how good they are. But yeah, I would be interested to know the Balun manufactured by Chris, how it works. I am glad you mentioned that, because it will definitely increase MWDX capabilities with 2 or 3 loops I have.
I can see your trouble with the nearby AM stations causing splatter. I too have the similar problem. I have this AM relay transmitter about 5 miles west of my house. Due to that, if I point any antenna to the direction, it just gets overloading from the AM signals. :( So, my DXing on anything coming from west is limited.
The only way to resolve the problem is either I move house to somewhere else, or waiting for shutting down the transmitter for good. A lot of AM transmitters get shut down recently either their going for DRM or for other reasons, so ... hope is still there. Failing that we will move to somewhere else countryside peace and quiet and ideally near the sea :D
Yup, the most important thing is, to listen to the bands and getting the DX. Time is short. I stopped most of other radio activities such as ham radio, DIY home brewing etc. Because SWLing alone is enough taking most of my spare time. I will get back to Ham Radio, when I am retired and settled with plenty of time then :)
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Phasing two antennas involves mixing the signals while adjusting both the relative phase of the incoming RF as well as the amplitude, so you can get cancellation of an offending station/signal. So it is a bit more involved than using a T adapter.
There are hardware phasers (MFJ-1026 for example), and you can also do it in software if you have an SDR with two RF inputs (SDRPlay RSPduo and SDRuno, AFE822x and SdrDx for two examples).
If you can come up with a way to creatively use a rotor, that might be the best solution.
If you cured the noise/RFI issues with your Wellbrook by using ferrite chokes on the coax and power cables, most likely the issue was common mode pickup on the cables, not the offending signals getting picked up by the antenna itself, as chokes don't remove that.
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After looking at the minimal components inside the affordable eBay phasing units, I would suggest probably opting for something a little more developed at the cost of a few more dollars.
Interesting timing with the discussion, too. I have a phasing unit currently on order with igor_us4lg via eBay. His models are $73 to $77 USD shipped depending upon the casing, knobs, etc. Shipping could take awhile because of him being in the Ukraine, but the delay is likely no worse than many of the China-based electronics sellers these days.
https://www.ebay.com/usr/igor_us4lg
Big pluses for me? His boards look well built, his posted schematics appear reasonable IMO, and he has 100% positive feedback with hundreds of transactions.
Update.... one particular note to add. Most of the off-the-shelf phasing units on the market are designed for HF frequencies. There are mods to extend mediumwave capabilities, but be prepared to remove and change components. For example, W8JI has info on modifying the MFJ-1025/1026 phasing unit to bypass the ~1.9MHz highpass filter and decrease the lower frequency limit.
https://www.w8ji.com/mfj-1025_1026.htm
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Unfortunately, I believe that ferrite are now part of the hobby. I use them as well along with some special AC line filtering. I have the ferrites installed at the cable entrance to the house. I found that walls are noisy. I might put some additional ones at the antennae this summer, but chokes at the antenna input are not so critical unless the antenna is the victim, I.E. noise is travelling up the coax toward the antenna and the antenna is picking up or worst, transmitting the noise. Chokes at the antenna are more common when transmitting or if there is some down-converter or amplifier at the antenna being fed by a noisy switching power supply. I had this problem with the mini-whip antenna. It was the source and my other antennae were the victims. Needless to say, no dirty switching power supplies in my installation. They are all replaced with old fashion analogue power supplies with good filters.
At the receiver input, I have a common mode noise filter. I managed to squeeze 10 turns of coax on a ferrite core. After several months of stock shortages, Palomar Engineers is finally shipping some of their products that were previously hard to obtain. I have been wanting to replace the VALCOM ATU that you see in the previous picture. It is a broadband (receiving) matching transformer, 100 kHz to 30 MHz. It is designed for a 35 foot vertical whip antenna. It will be replaced by a Palomar Engineers Bullet 50:450 (9:1) VLF HF UNUN (20 kHz to 30 MHz). I have 2 of them in transit. One for the end-fed antenna and a spare to play with. I can also transmit in the bullet. The VALCOM ATU is good, but it is in a water proof aluminum enclosure and is very heavy. It needs to be mounted, not hanging from the guy wire like I have it installed. All this to say that I also have a Palomar Engineers common mode noise filter coming in the shipment. The home brew will move over to the Icom.
Don't forget the other sources of EMI in your house such as cable / satellite TV boxes and believe it or not, ADSL/VDSL modems can be incredibly noisy. It took me a long time to hunt that one down. My Icom had a constant shhhhhhhh noise in the background. I went around with a special EMI test antenna and receiver to find that one. I unplugged the unused telephone line in the room and the noise went away. I don't get that one. I tested the phone line, inserted an ADSL filter, plugged in a phone to terminate the line and I just couldn't get ride of the noise. It's a strange one. Some day I will get back into it.
Now, time to update everyone on my new Flamingo AM broadcast band notch filter. So far so good. First impression is that the filter works very well. I will take it to the bench on the weekend and sweep it to see if it meets the specified specifications. Even with the filter, (>40dB typical, 350 kHz and 1900 kHz) there is still plenty of AM signal left from the Wellbrook for some good DXing. Below you can see 1540 kHz splattering all the way above 5 MHz and up. The second screen shot is with the filter inserted at the receiver input. Looks good. The 3rd screen shot is a slice of the AM band, still lots of signal there to play with. I wanted to grab a screen shot of 1540 kHz but they switch to low / night time power at 00:00 UTC and I just missed it.
(http://www.milspec.ca/board/img/nooelect-flamingo-am-broadcast-band-notch-filter-test.png)
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I have various ferrites on feedlines, powerlines, etc. I also have KD9SV common-mode chokes back near the receivers for a couple of my better antennas. KD9SV rates them for 3000 ohms of resistance at lower HF frequencies, so I suspect probably mix 31 or maybe even 73/75 ferrites underneath the potting material.
I have UPSs with power filtering on several electronics, though the radios typically get automatic voltage regulators with line filtering instead, as I am not too concerned about power backup for them. I like and use the APC Line-R series, though the 600VA baseline model starts around $50 new these days.
Otherwise, you can find used good condition ESP XG-PCS-15D and similar office copier-grade line protection models with filtering for around $20 to $25 shipped on eBay.
About the modem, check the power supply, especially if it is a wall wart. It could be a switching PSU with little to no regulation and filtering, though I have seen even linear supplies with similar issues as well. A few turns of the power cord on a common mix 31 or 43 ferrite might help.
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BTW, while on the topic, Chris here at HFU offers a couple of interesting matching transformers as well. :)
https://www.blackcatsystems.com/rf-products/potted_matching-transformer-unun-balun-beverage-longwire-k9ay-flag-ewe-dipole-antenna-shortwave-ham-radio.html
https://www.blackcatsystems.com/rf-products/cyclops_rf_ham_shortwave_radio_matching_transformer.html
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Yup, Phasing 2x Loops can really increase MW DXing capabilities I thought. MFJ 1026 seems way too over priced for what it is. QRM eliminators on eBay from China seem going for about 40 - 60 Euros. But recently they started adding taxes after you click on Buy It Now, and then you find the total is far more than what was showing as the price. Not good. I was hit by this new system on eBay, and stopped buying anything from overseas sellers.
But the Russian made units seem good, as you say price seem higher, but if they are made of better parts and work better, then maybe worth it?
I think my Wellbrook Loop has a poor quality PSU. The loop is older type which gets fed with -12V in the centre, so it will not accept any PSUs, hence I am kinda stuck with the PSU. It seems the PSU was either generating high noise or was picking up the common mode RFI. As I said a bunch of small ferrite filters on the leads seems to have cured the noise.
I too bought a few packs of the ferrite filters, and was regretting having bought too much of them, but before soon, they all ran out. I will need more of them.:(
It is strange my other active loops MLA30 don't seem to have this noise problems, but they are just noisy on certain bands.
There seem plenty of ideas for good MWDX antennas. Flag and phasing the loops seem definitely good idea, and there is recommendations for Beverage, but it requires large piece of land space of at least 100m I gather. My back garden is only about 20 x 20m max. But what I feel is that you don't need large antennas, because they might also be picking up more noise?
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I think my Wellbrook Loop has a poor quality PSU. The loop is older type which gets fed with -12V in the centre, so it will not accept any PSUs, hence I am kinda stuck with the PSU. It seems the PSU was either generating high noise or was picking up the common mode RFI. As I said a bunch of small ferrite filters on the leads seems to have cured the noise.
If you cannot find a -12V linear DC supply locally (they do exist), you could take a +12V linear DC supply and swap the wires to provide the necessary -12V output.
But what I feel is that you don't need large antennas, because they might also be picking up more noise?
If you live in a RFI filled urban environment, you may not get much benefit from a large antenna. But in a rural environment, you most likely would. I certainly do ;D
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Hey All.
Alpard: 20X20 M is a fairly big area and without getting overly specific, I feel that a lot could be done in that size space.
Just to try something different, a number of years ago, I had reading about low noise (wire) antennas for HF/B'cast.
These sometimes required multiple grounds , multiple chokes, etc, etc. I never built any because I couldn't meet the specs required.
So a search for "low noise antennas" may get you somewhere.Perhaps you can quickly find the "class" of common mode choking wire antennas that I refer to here.
What wave lengths you'd want to construct these- perhaps there are different schools of thought as to how long to make them and how to construct them. Long has it's has good points
but in an overloaded big signal and/or big noise environment maybe big isn't so great either, even re dx. Q is the key and a circuit that uses more variable capacitance and less inductance at the desired wavelength could be given some consideration. Also short 3 wire 20 or 30 ft flat top spaced at 3 ft between wires .It's all bonded on feed line end and all open / NOT bonded at the far end.
Feed line Shielding or feed line spacing will probably apply.Again, just a class or two of home brew inexpensive antennas could be tried for grins. Maybe they are for you, maybe not.
Not sure what may be worst of your issues: Arc/ power line noise -or- local "device noise ( plasma TV's noisy power supplies, etc) -or -local broadcasts or other strong RF from off far away.
So your mileage , options and interests may vary.
Not sure if you have played with medium sized air loops (with /or with out low Z coupling loop/coax fed) . Or air loop just coupled to ferrite.True, it is a VERY small antenna compared to large out door custom arrays. But they have some very interesting properties and I have found them a lot of fun to play with IF built well.
K
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I was going to cut the lead and connect it back with the polarity reversed of the other PSU I have, if the ferrite filters on the original PSU didn't work. But it did. :D
I was thinking that too. Countryside open field or near the sea side location with clear and high open space would be best for Radio work with big and large antennas.
Otherwise, in the residential areas and for the small garden house dwellers, maybe smaller antennas such as Active Loops are more suited?
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Also all sorts of types of counterpoise and ground rods experiments-and- Shortish verticals with evenly spaced out loading coils with radials or screen -or- rods or spaced out rods AS antenna-or-single rod AS antenna, etc, etc. ALL sorts of options re all different types antenna designs and the different types of noise being encountered,
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I concur with the APC Line-R. I use them exclusively although they are protecting the servers, network, PC, TV etc ... that do not require a UPS. My AC line filtering is exclusively accomplished with Topaz Ultra-Isolation Line Noise Suppressor Model 91001-31 transformers. They are generally well recognized in the broadcast, audio recording industry, medical applications and labs. Their common-mode noise rejection is 146 dB @ 100 kHz and normal-mode noise rejection is 65 dB @ 100 kHz. Efficiency is 95% typical. You want the ones with 0.0005 pF inter-winding capacitance. A cheaper alternative is to wire a Corcom (or equivalent) EMI filters backwards, I.E. the AC line connect to the load side of the filter and the line side of the filter connected to the radio. Most of these filter are designed to prevent equipment from leaking noise back into the power line so when you flip the filter around you are preventing AC line noise from leaking past and into the radio.
As for the modem, this is an interesting item to watch:
VDSL RFI Detection and how to report it to OFCOM https://www.youtube.com/watch?v=tpcWYoDEh7U (https://www.youtube.com/watch?v=tpcWYoDEh7U)
The software and information can be found here:
https://rsgb.org/main/technical/emc/vdsl-interference-reporting/ (https://rsgb.org/main/technical/emc/vdsl-interference-reporting/)
In a nut shell, you take an I/Q recording of suspected interference and you run it through the software for analysis. There are also sample I/Q files on the site that can be used for testing purposes.
Ok, now we are completely off topic but what the heck, 300+ views so I will take it as there is some interest in the tread.
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Also all sorts of types of counterpoise and ground rods experiments-and- Shortish verticals with evenly spaced out loading coils with radials or screen -or- rods or spaced out rods AS antenna-or-single rod AS antenna, etc, etc. ALL sorts of options re all different types antenna designs and the different types of noise being encountered,
I have a few redundant mobile whips for HF ham bands. Could they be converted / modified to work for MW DX Rxing by adding loading coils and stuff. Not sure how efficient it would be for MW DXing though.
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In a nut shell, you take an I/Q recording of suspected interference and you run it through the software for analysis. There are also sample I/Q files on the site that can be used for testing purposes.
Ok, now we are completely off topic but what the heck, 300+ views so I will take it as there is some interest in the tread.
No probs. They are all related to each other, and we are learning something about them. That's cool.
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I like and use APC for UPSs, but my two old Opteron 32-core servers and various network equipment are on an Eaton 5PK 1500. I scored it for under $50 new in the box via eBay. ?! I suppose nobody wanted to pay the shipping cost. It was a local pickup for me. :)
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If those are loaded HF whips, you might find a combination of load coils and one of the whip sections to end up near "resonance" at some exceedingly tiny slice of the MW band. The other issue will be efficiency, which could fall to a few or even a fraction of a percent as frequency decreases. Both are products of the wavelengths involved.
For example, if unloaded, you would need an ~139 meters to build a quarter-wave vertical and a decent ground radial field to be near resonance at 530KHz. o.0
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If MW DX is a distinct interest, have you looked into building a serious ferrite rod loopstick antenna? Not just a single ferrite like in a portable radio, but up to several large ferrite rods stacked together. Also you would need litz wire for winding the coils, a suitable tuning capacitor, and probably a length of PVC pipe as an easy-to-assemble casing.
Another popular DIY project for AM reception, though less exotic and potentially less performant than a stacked ferrite loopstick, is the box loop antenna. All you need is 2-4 supports, some wire, and a variable capacitor.
Either can be made to be remote mounted, remote rotated, and even remote tuned if you want to spend the time, effort, and a little money building them.
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On a side note, I am curious if you have tried any of the off-the-shelf airloop tuned MW antennas? I have a Tecsun AN-200. Costs about $35. I am not really into AM BCB radio, so I can not give a thorough review, but it does null and peak signals decently with my G3, PL-330, etc. radios assuming there is not highly intrusive RFI noise from a multitude of directions. Also, it is compact and light enough to take along with a good portable receiver to a hopefully more RFI quiet location, like maybe a local park or similar.
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On a side note, I am curious if you have tried any of the off-the-shelf airloop tuned MW antennas? I have a Tecsun AN-200. Costs about $35. I am not really into AM BCB radio, so I can not give a thorough review, but it does null and peak signals decently with my G3, PL-330, etc. radios assuming there is not highly intrusive RFI noise from a multitude of directions. Also, it is compact and light enough to take along with a good portable receiver to a hopefully more RFI quiet location, like maybe a local park or similar.
Ditto on the AN-200....wonderful bang for the buck !
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3 for 3 for the Tecsun AN-200. I had seen this review https://youtu.be/F8Jlu2NuPWo (https://youtu.be/F8Jlu2NuPWo) and by shear luck I later found one sitting on the shelf at a local surplus dealer a couple of months ago. I took it home, gave it a nice cleaning and assembled a BNC adaptor to be able to connect it to a receiver. I cannot give an honest review at this time since I have not had much opportunity to play with it so far but it is a nice loop antenna.
Here are a couple of sites with an anatomy of the AN-200.
https://antiqueradios.com/forums/viewtopic.php?t=261183 (https://antiqueradios.com/forums/viewtopic.php?t=261183)
https://www.qsl.net/lx2sm/html/tecsun_an-200_infos.html (https://www.qsl.net/lx2sm/html/tecsun_an-200_infos.html)
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I do have an AN-200. I have not thought it can pull the MWDX signals from the other part of the world.
It was OK for pulling low powered AM stations from hundreds miles away right enough.
I used to use it a few months ago, but put it away somewhere. Will need to find it, and put it on again.
The other thing about AN-200 is that, it worked better magnetic way. It was great for portables, but
not very good for the desktops without ferrite core antennas. It wasn't working great with my R75 when connected
via 3.5mm headphone jack, and then PL259 adaptor.
Would it work ok with SDRs?
What kind of DX signal can it hear?
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The MW DX signals are going to be arriving via skywave propagation, so your best bet with the small AN-200 is being outside. A small airloop is about directivity and circuit Q, with the antenna tuning capacitor acting not only to peak signal transfer for your portable, but also to act as as a sharp passive preselector.
Grab a portable with known decent AM performance. Go outside at night, preferably when it is dark in both your and the desired DX area, and hopefully find a RFI quiet location. Having a small table for the radio and antenna can help; plastic or wood would be preferable to a potentially RF-conductive metal table.
Rotate the AN-200 to null local RFI and/or local AM stations, tune the antenna carefully to your radio's frequency, and start listening closely around the noise floor. *Headphones* can help. No guarantees, but you might be surprised, especially if you have been using the AN-200 inside a RFI-filled house like many usually do.
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Another ditto on the AN-200, it can provide much performance enhancement of a portable.
Another use of the AN-200 is in its ability to inductively couple a "longwire" antenna to a portable.
Most portables rely on the internal loopstick for MW reception and do not provide a means for connecting
an external antenna (typically, the whip is used for SW and FM and the external antenna jack is for SW only).
Plug the wire antenna into the AN-200 via its 3.5mm jack and place the loop near the portable so as to
inductively couple the signal into the radio. You will lose much of the directional capability of the loop but
you will gain the ability to use the wire antenna.
Regarding the MFJ 1026, it is worth every penny as it oftentimes in a noisy environment is the difference between
hearing a signal or just listening to the noise. However, you will have to modify it for use on MW and below.
This involves removing the high pass filters on the main and aux inputs.
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Be careful of the AN-200's 3.5mm connection. At this link https://antiqueradios.com/forums/viewtopic.php?t=261183 (https://antiqueradios.com/forums/viewtopic.php?t=261183) you will find the author describing that "The 3.5mm female stereo jack that is used for the external antenna connector. Only the Ground and first ring are used on the male connector the tip is not connected to anything" This is the way I built my adaptor, ring and ground.
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Great info and advice. Thanks.
Will try out with my AN-200 again with the ideas suggested here.
MFJ1026 was just too expensive for my budget.
I was seriously thinking of getting the Chinese made QRM eliminator but it also seems cover from 1Mhz only,
not fully covering MW band. The price was good, I was offered 38 Euros from the seller for it
including delivery.
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Be careful of the AN-200's 3.5mm connection. At this link https://antiqueradios.com/forums/viewtopic.php?t=261183 (https://antiqueradios.com/forums/viewtopic.php?t=261183) you will find the author describing that "The 3.5mm female stereo jack that is used for the external antenna connector. Only the Ground and first ring are used on the male connector the tip is not connected to anything" This is the way I built my adaptor, ring and ground.
Indeed. I read "The 3.5mm female stereo jack that is used for the external antenna connector. Only the Ground and first ring are used on the male connector the tip is not connected to anything."
Also "
airrace48 wrote:
Do you think that I could connect the AN100 to my antenna terminal utilizing the connection point on the AN100 shown in your photo with the red arrow? What about my ground terminal?
It would probably not work very well with this radio as it looks like from the schematic that it works best with a long wire. You could try it, it probably would not hurt anything but the an-100 antenna is really meant to be electromagnetically coupled with a sets built in loop antenna."
This is a vital critical info on this antenna I take it.
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The pigtail that came with my AN-200 is equipped with a 3.5mm stereo plug. Plugging it into the AN-200 results in my reading continuity between tip and sleeve.
There is no continuity from the ring to either tip or sleeve. Plugging in a mono plug also gives continuity tip to sleeve.
To add to the possible confusion, the reviewer in the post #23 link called it a mono plug and the antique radio forum poster linked in post #27 opened up an AN-100, not an AN-200.
My AN-200 does not look like it can be easily taken apart without possibly destroying it so for now my guess is that the tip is the antenna connection.
Also, FWIW, be aware that the external antenna jack on portable radios can be mono, or in some cases, stereo. The owner manual may not be very clear regarding which type.
You will have to make the proper determination for yourself.
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I use a mono cable to hookup the AN-200 if needed. An 1/8" connector to 1/8" connector for portables, or an 1/8" connector to RCA connector with the appropriate adapter for desktops. Not sure I bothered checking the hookup for continuity, but it works as expected, so.... :)
As pinto vortando noted, the AN-200 also works nicely for coupling other antennas for MW to portables. I have used it to couple my 148' LoG to various portables. The AN-200 loses directivity of course, but it still maintains enough circuit Q to continue working as a passive preselector.
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Managed to dig out my AN-200 from the attic. I had a close peak on the 3.5mm input jack on the AN-200, and it says "Antenna Output".
This made me think that the pig tail 3.5mm connects to the input socket of the AN-200 which says "Antenna Output", and could be connected to my R75 PL259 via adaptor. It worked very poorly, and I threw it away to the attic for all that time.
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Managed to dig out my AN-200 from the attic. I had a close peak on the 3.5mm input jack on the AN-200, and it says "Antenna Output".
This made me think that the pig tail 3.5mm connects to the input socket of the AN-200 which says "Antenna Output", and could be connected to my R75 PL259 via adaptor. It worked very poorly, and I threw it away to the attic for all that time.
The AN-200 probably won't do much for your R-75. It is intended more to improve reception of a portable.
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pinto vortando - Plugging it into the AN-200 results in my reading continuity between tip and sleeve.
Thank you for that additional information. My surplus AN-200 was missing the cable and I found it odd that they would have used ring and sleeve. I did initially check all of the possible combinations with my LCR meter but could not determine which pins were active. It is possible that there is something wrong with my antenna. It did come from a surplus store after all.
As with yours, my AN-200 did not look like it could be easily dismantled without potentially damaging it.
As mentioned earlier in post #7, I subjected the NooElec Flamingo filters I purchased to some bench tests late this past afternoon. More to follow. I will post the results here on this thread.
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I have used the AN-200 on my Kenwood R-2000 through the receiver's low-impedance input, though I used a variable gain preamp to handle the (huge?) mismatch. I only tend to do something like that if/when my outdoor antennas are disconnected, like during a storm, yet still wanting some radio nois... err, music or whatever in the background.
Suppose I could peak the AN-200 for an arbitrary MW frequency, then measure it with a VNA to get a better idea of its electrical characteristics. Maybe later tonight or tomorrow.
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I did a *very quick test* with a NanoVNA-H4. There was some measurement bounce due to stray capacitance, as in likely my proximity to the setup.
Peaked the AN-200 at 850KHz. Approximately 950-j245 with a SWR over 20:1; give or take maybe 5 to 10 percent. Even with the error margin, that means a considerable mismatch to a lower impedance input for an already negative gain antenna.
In the case of the AN-200, a standard 9:1 balun likely would help considerably if direct connecting to a low-impedance receiver input, such as the usual ~50-ohm jack. Around $15 on eBay, or wind ya' own. An alternative could be a low-noise preamp as I previously noted using with my Kenwood desktop.
BTW, some desktop receivers have high-impedance inputs, though those are often just paths through 4:1 transformers to the usual internal low-impedance circuit inputs. That 4:1 could help, though a 9:1 or slightly higher ratio connected to the low-impedance input might prove superior for signal transfer.
As for portables.... yeah, those 1/8" and similar small inputs can be all over the place. I would start with a 4:1 or 9:1, though perhaps even no transformer at all might suffice. Huge YMMV. Otherwise just capacitance couple the AN-200 to the portable's internal MW ferrite loopstick antenna. ;)
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If the OP really wants to investigate which MWDX antenna would work best for him, my suggestion would be to visit the International Radio Club of America (IRCA) website and check out the free reprints available covering all types of MW antennas. Another source would be the National Radio Club (NRC) Antenna Manuals volumes 1 through 3 as well as their Design and Theory manuals covering Loops, and Beverage and Longwires... five books in all that along with the IRCA reprints should be more than enough to satisfy the MWDX enthusiast.
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As mentioned earlier in post #11, I inserted a NooElec Flamingo AM filter which I purchased to overcome the strong RF signals from AM transmitters near to my location. I purchased both the enclosed versions of a Flamingo AM and a Flamingo FM for evaluation. Both filters are well built and assembled. I performed some bench tests at specific frequencies to test their frequency response. Both filters performed as advertised by the manufacturer and I am pleased with them. Below you will find the filter response charts based on the tests that I performed using my HP/Agilent instruments.
(http://www.milspec.ca/board/img/nooelec-flamingo-am-filter-frequency-responce-performance.png)
(http://www.milspec.ca/board/img/nooelec-flamingo-fm-filter-frequency-responce-performance.png)
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They look excellent filters from the graphs. Thanks SIGINT.
I too sometimes suffer from overloading from an AM transmitter about 5 miles west of me.
So, if I point my loop to the West, then I get the strong AM signals from the transmitter all over the band popping up here and there everywhere.
This is a big problem. So I have bought a set of Kiwa filters for MW and LW. They are very old filters, and seem work OK.
Trouble is that now I do lots of listening for on MW DXing. When the MW stop filter is on, then the weak signals on MW gets blocked off.
So I must add some sort of switching to take out the filter when MW BCLing. On SW BCLing, I need to switch on the MW blocking filter on.
I still hadn't add the switch, so ended up taking off the filter all together because SW condition is so poor, I hardly now listen to SW bands.
Just odd tuning around there, but mostly tune about MW bands for night time DXing. It has not been great either for DXing.
But I am still planning to add a 2 way switch for those filters. The Kiwa filters are now out of production for some reason, but they are excellently built with heavy duty metal casings.
I wonder how you are using the filters and what your set up is. I guess it would depend on what bands you listen to most.
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If the OP really wants to investigate which MWDX antenna would work best for him, my suggestion would be to visit the International Radio Club of America (IRCA) website and check out the free reprints available covering all types of MW antennas. Another source would be the National Radio Club (NRC) Antenna Manuals volumes 1 through 3 as well as their Design and Theory manuals covering Loops, and Beverage and Longwires... five books in all that along with the IRCA reprints should be more than enough to satisfy the MWDX enthusiast.
I feel they are all related and good to know even not directly related to the OP. Initially I was curious what other MWDXers own and run for their DX antennas for the band, and what sort of DX signals they are hearing with them.
But I feel every idea and post is valuable for me for my learning the subject = MW DXing antennas
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Hey All,
More random comments :
Quite an interesting concept to think of a loop as a "pre- selector". Also ,a loop certainly may not be a "substitute" for a serious outdoor wire antenna (of any type). A supposed rule of thumb ( not sure if exactly true or not ), If- a loop has ie, 100 ft of wire, even if well built,it supposedly grabs only 1/10 of the energy of a well built outdoor 100 ft long antenna (comments ?). But Q and directional ability are the advantages.
I have used both and REALLY liked having both at my disposal,way back when. Unfortunately, any serious outside wire antenna is now out of the question for me .So it's loops or pretty much nothing.
I suppose each QTH is different re the type of noise encountered, operator's "goals" , etc. One size (re anything) may not fit all.
Obviously one main focus , IMHO, is Q .Not matter what you build, be it small tank ,loop or long wire or ground run. And at least in my experience with my (long gone) ultra high performance DX crystal sets, the takeaway is save every tiny bit of Q you can. It adds up.
Insulate and insulate again. Radio "loves" air- not solid surfaces. I even used to air stand off ground runs until it reached rod. Maybe overkill to some, but Q bleeding seems to hide in some unexpected places.
In my experience any serious home brew tank/loop,etc, starts with the var cap. It is the first (and maybe the worst) place things can go wrong,IMHO .To me , nothing can replace a 500 pf 4 gang ceramic ( very important that it be ceramic )wired 2 gang as one leg, two gangs as the other. This will eliminate rotor loss. Such caps are often found in old signal generators. If purchased on line, they can be expensive. But WORTH it. I was cheap with mine and enclosed them in airy styrene boxes with ceramic stand off insulators and quick solder terminals. That way I can hard solder them into whatever project I feel like and not have to buy 12 of them (ha, ha). 6:1 (or better) Ball drives and shaft insulation , panel shielding, etc, are musts with theses caps. A definite "investment".
4 gang ceramic did well quite even with solid copper #20 cotton covered wire coated with poly. Such coils with bakelite var caps were noticeably down , even just by ear.4 gang ceramics with 660/46 litz are simply stunning.
Back in the day, I took one of my 660/46 ferrite tank coils off the xtal set and coupled the long wire to the Panasonic's ferrite.
With no ground wire on anything, the results were incredible. Station audio was pinched up really tight and you would swear you were listening to a regen.The selectivity was awesome. Using a ground knocked things down a lot.
I guess any air loop , tank , external ferrite bar coupler , etc are only as good as the components and insulation and the good practices/ techniques used.
I gotta try another BIG Fe external coupler some time.I had SO much of this stuff before the "Great Purge" of 2019. I regret tossing a fair amount of these items (some of which which I MAY reacquire, maybe ) , but the situation dictated it then .Oh well.
Also re air loops used on 50 ohm receivers : I have always been a bit concerned (maybe unfounded) that it has loss written on it (Unless you are talking Kiwa high dollar /50 ohm designed/ regen loops. I had a friend who had one.The performance would blow you away).
I think it would have to be done right to (maybe) get it to work well . Just having a ratio'ed secondary wound right on top of the tuned primary may not be so hot . My understanding , is that the pick up winding may also need to be properly spaced away from the tuned primary as well as ratio'ed. On the AN -200 or a Select -a -Tenna with a jack, this isn't practical due to space considerations . Just too big for a "grab and play" type of store bought antenna.
Even simply tapping an air loop way down for 50 ohms may cause a (serious ?) Q reduction re loading the loop ( comments ?). Admittedly, I have not tried this, so maybe I am not the guy to comment.
I'd say knowledge of RF physics is at a "low to moderate level " (at best) , so if I am off base on anything , I welcome correction for both myself and for the group to learn from .
de NQC
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The primary issues with the original inquiry are limited lot size, local RFI, and a nearby AM BCB.
If a rural location with plenty of space, I would say more like a phased beverage antenna system would be a good starting point for the OP.
Even simply tapping an air loop way down for 50 ohms may cause a (serious ?) Q reduction re loading the loop ( comments ?).
Likely so assuming it was being done in the actual small airloop design, such as trying to get a coupling winding to present a ~50-ohm load, which probably is not happening anyway with these small airloop antennas anyway.
I suspect a transformer at the feedpoint (should?) be "okay enough" for our purposes. If a transformer at the feedpoint does significantly affect Q, then a low-noise preamp at the the feedpoint or even along the feedline to help overcome the match losses if needed could be used instead.
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I wonder how you are using the filters and what your set up is. I guess it would depend on what bands you listen to most.
For now, I have only been testing the AM filter. My intent was to leave it in-line all the time as opposed to switching it in or out of the circuit. The theory behind that is to prevent receiver input overload, regardless of the band I am listening to. Input overload can produce what is called receiver de-sensing. De-sensing occurs because the IF AGC is reducing the input gain due to the presence of high level local signals and as a result reduced the receiver's sensitivity. I did a quick dirty test this morning and having the filter in or out of the circuit does affect receiver performance. With the AM filter out of circuit, the baseband noise floor was at -121dB. With the AM filter in-line, the baseband noise floor increased to -117.4dB. This means the receiver was admitting nearly 4dB more signal with the filter installed (pictures below).
So far, having the filter in-line has improved my AM band DXing. Without the filter the power house broadcast stations just hammer the IF AGC. With the filter the AGC attenuation level is lower and the receiver is admitting adjacent channels much cleaner. AM band DXing in my area is not all that interesting. Everyone carries the same boring syndicated sports or radio talk shows. Being on the border of Canada and the USA, I get syndicated junk from both sides. The real test will be when I go back and check my beacon list. Back in late February I logged 391 kHz, DDP, San Juan / Dorado / Luiz Munoz Marin Intl, Puerto Rico. That is nearly 2,000 miles away from my receiver location. Not bad for what is reported to be a 3kW NDB with a 200' vertical.
Nice find on the Kiwa filters. I had forgotten about those but I remember them being well regarded back in the days.
(http://www.milspec.ca/board/img/nooelect-flamingo-am-broadcast-band-notch-filter-baseband-noise-test.png)
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My interest is HF, so I am more inclined to outright high pass MW BCBs with more extreme attenuation if absolutely required.
One of the best solutions I have right now is a PAR BCST-HPF 7th order elliptic high pass filter. Roll off below 160m is dramatic. Pair it with a preselector for even more dramatic results.
http://www.parelectronics.com/bcst-hpf-specs.php
https://www.eham.net/reviews/view-product?id=5086
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Rob,
Thank you for the source of the filters. There are some nice products on that site.
There was a Chris Scott & Associates AM Band Notch Filter a few months back on ebay that I just missed. By the time I did my research on it and went back to purchase it someone else had snatched it up. I have been keeping an eye out to see if another one ever shows up again.
https://scott-inc.com/ (https://scott-inc.com/)
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The CSA filter looks nice for a true MW enthusiast. :)
PAR was perhaps more popular for its end-fed antenna brand, though it eventually sold it to LNR, which in turn eventually sold it to Vibroplex.
https://www.vibroplex.com/contents/en-us/d9175.html
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Great post NQC. Thanks!
Yeah, I agree with you. If I had acres of land, then I wouldn't toil with the MW DX antenna ideas.
I would just have gone and put up a beverage or sky loop in full wave, or even a proper long wire End Fed or L shape would work great.
But as said, our garden is only 25x25 meters, which is not great for the full size antennas. Hence trying to do with the smaller antennas which will do the job.
Active antennas are costly if from the commercial sellers, and DIY takes time and trial error course, which steals the valuable time for SWLing :)
Also the big antennas in built-up areas are prone to pick up RFI noise QRN. So, this has been always tricky part in the hobby.
I am still thinking of making up a tuned square or delta loop of about 1m for each side, and variable capacitor, and magnetic pickup loop inside the larger loop.
I have seen these type of magnetic loops work well in ham radio operation. Disadvantage being very narrow bandwidth. But Q seems very high, and good for rejecting QRMs and QRN. Also they seem very directional too. Seems also very cheap to make, as all you need is some wire, frame, coax and a variable cap.
It is one of the future project here :)
But meanwhile I would be still try to find out what are some great MWDX antennas, and what antennas other DXers are using, and what they were hearing with them.
SIGINT
The KIWA filters are excellent in their performance too. I am not sure how old they are, but cannot find much information about them these days.
I figured out I would need 2x 3 way antenna switches (1x to the RX, 3x connectors = 1x to LW and 1x to MW fitter and 1x to straight through) and 1x to the antenna) to connect them, but I am kinda wondering the best way to connecting them up, so they can just be inline or offline by a flick of switching. I think I will need to get a lot of patch leads to implement it. This does not seem simple or tidy set up, which I am apprehensive about.
And I will try out using the AN-200 again too. I quite agree with you. The AN-200 looks as if it will crack and break, if pried open inside. The flimsy looking plastic casing is not held by any screws. Must had been glued on or just clipped on each other?
Having said all that, I find active antennas work incredibly well for LW and some part of the HF especially 9 and 11 Mhz.
I was under the impression also, that something could be added onto them to heighten MWDX performance. Just wasn't sure what they could be.
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Well, Mr. Google to the rescue. Kiwa filters still appear to be very much active, at least their web site https://kiwa-electronics.com/ (https://kiwa-electronics.com/) is current. They also appear to still have the receiver upgrade filters (including the Icom) located at a different URL: https://www.kiwaupgrades.com/ (https://www.kiwaupgrades.com/)
Since we are still on the subject of loops, before venturing into the commercial purchase of my loop I built myself a test loop antenna in order to run a series of tests and determine if the investment would be worth the money. It was nothing more than a piece of left over heliax, a home built matching transformer (inset in the picture below) and a water proof electrical box from the local hardware store. A word of caution if building one, do not use N type connectors. The wind load on this antenna was sufficient that they would constantly come loose. If I was to do it over again I would use PL-259s and SO-239s, and not the cheap ones with 2 or 4 notches. The antenna worked pretty well on its own without the use of a preamp or tuning circuits.
(http://www.milspec.ca/board/img/home-built-loop-with-matching-xfmr.png)
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The real test will be when I go back and check my beacon list. Back in late February I logged 391 kHz, DDP, San Juan / Dorado / Luiz Munoz Marin Intl, Puerto Rico. That is nearly 2,000 miles away from my receiver location. Not bad for what is reported to be a 3kW NDB with a 200' vertical.
OO Oshawa ON dominates 391 here most days but can hear DDP when the propagation is right... the wider offset of DDP helps.
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My interest is HF, so I am more inclined to outright high pass MW BCBs with more extreme attenuation if absolutely required.
One of the best solutions I have right now is a PAR BCST-HPF 7th order elliptic high pass filter. Roll off below 160m is dramatic. Pair it with a preselector for even more dramatic results.
http://www.parelectronics.com/bcst-hpf-specs.php
https://www.eham.net/reviews/view-product?id=5086
My interest is mainly below the AM BCB. Have found the PAR BCST-LPF very useful in attenuating AM stations.
Also found that using it along with the MFJ 956 tuner helps.
Big fan of the PAR EF-SWL antenna... Good for LW through HF. Lengthened one of mine for LW/MW work.
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Thanks for the link. Fantastic. Good to know they are still in business and going strong.
I have this one.
https://kiwa-electronics.com/kiwa-bcb-rejection-filter.html
and this too.
https://kiwa-electronics.com/500-khz-low-pass-filter-3.html
They work well, and are built like tank.
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It was nothing more than a piece of left over heliax, a home built matching transformer (inset in the picture below) and a water proof electrical box from the local hardware store. A word of caution if building one, do not use N type connectors. The wind load on this antenna was sufficient that they would constantly come loose. If I was to do it over again I would use PL-259s and SO-239s, and not the cheap ones with 2 or 4 notches. The antenna worked pretty well on its own without the use of a preamp or tuning circuits.
(http://www.milspec.ca/board/img/home-built-loop-with-matching-xfmr.png)
Looks simple but tidy and well made.
Thanks for the tips for building one. Great advice.
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Well, while we're on the subject, here's this dude's loop. https://swling.com/blog/2021/04/giuseppe-is-impressed-with-the-performance-of-his-homebrew-passive-loop-antenna/
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The "Noise-Cancelling Passive Loop" is basically a homebrew Airspy Youloop.
https://swling.com/blog/2020/04/diy-how-to-build-a-noise-cancelling-passive-loop-ncpl-antenna/
I have a Youloop, and it does work decently for a small portable HF antenna. Not sure I tested it much for MW, though. Also a YMMV on the litany of Chinese clones on eBay and similar.
I can confirm it is designed ideally for receivers with "high dynamic range" like the Airspy HF+ SDR models. The antenna design seems to have a decent SNR profile with some directivity, but its small size, widely varying impedance characteristics, and negative gain means a sensitive, low-noise receiver is preferred.
That said I have used my Youloop with portables for the HF band, though I ended up using a basic L-match tuner to deal with the mismatches in order to peak signal transfer.
I have a VNA plot and more details of my experience with it here:
https://www.hfunderground.com/board/index.php?topic=71326.0
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I as well have an AirSpy YouLoop. I picked it up at last year's black Friday sale. If I recall, it was nearly 50% off the price. I pay more for a large pizza with toppings than I did for the antenna. A large part of the YouLoop's success is due in part to the matching transformer. I would only ever order one from AirSpy or RTL-SDR (an authorized dealer). Most others are counterfeit.
Needless to say, I took it up North, like around the 49th parallel North, over the Christmas holidays and I had extremely good reception with it. It was hanging inside of a basement window and was pulling NDBs and MW broadcast stations 500+ miles away with no problem. I am almost convinced that loops operate best low to the ground. In several of the readings I did on loops, several suggested 1 loop diametre above ground. I have yet to prove that theory, nor was I at -40 degree temperatures over the holidays.
As for my experimental loop, it is currently set aside. I need to put a proper matching transformer in it. When I built it I used an unknown ferrite core. Essentially I just lined up a bunch of them on the bench and put them on the LCR meter and picked the one that had the highest inductance at 1kHz. What can I say, it was a weekend project. The transformer should really have a mix 31 or special mix 75 core. I don't know if I would spin myself another transformer. I'm considering ordering one of these pre-made units https://www.ebay.com/itm/Miniature-Antenna-BALUN-Transformer-for-Receivers/202968944265 (https://www.ebay.com/itm/Miniature-Antenna-BALUN-Transformer-for-Receivers/202968944265) It uses a Mini-Circuits transformer which are some of the best ones around. One of Chris's Jellyfish units would probably also work just fine.
Here is the completed home built loop. You will notice that it has the gap at the centre top. Today, the Wellbrook is sitting in its place.
(http://www.milspec.ca/board/img/PA185847.png)
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I have a YouLoop copy from China. Got it for 15 euros including delivery months ago last year sometime, and it is very very quiet. It pulled shocking DX a few times unexpectedly.
But compared to my Wellbrook Loop, it is not able to pull DX signals on MW and LW like the Wellbrook does.
I feel like the YouLoop is still good antenna for HF, and great for LPAM RXing on MW and LW within the country not too far away.
But for more hardcore MWDXing such as Trans-Atlantic DXing, the Wellbrook is still the best among my the all the other antennas.
It is just, recently I felt, even the WellBrook is not enough. I felt that I do need and search for something better than the Wellbrook, hence I am here.
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Sometimes and some frequencies, the Active Antennas work better, but on other times, the long wire antenna works better. Sometimes they both work ok. It just varies for the signal and for the day, and way the propagation works. So, I feel like it would be best to have different types of antennas installed and switch over for the best antennas for the time.
It is just recently they were all not too hot in pulling DX signals, and I was trying to find what else could be added or modded or upgraded or changed to the antennas for pulling more DX signals. Maybe the band condition has been very poor? Whatever happened to the new Sunspot Cycle 25?
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I have gone back and looked at my Tecsun AN-200 and I believe it has an issue. I can not find any continuity on any of the Ant Output connector pins. I tested it with an LCR meter, a multimeter and a spectrum analyzer and nothing. Disassembly is most likely imminent. I will have to go back and study all of the pictures to see if there are any clues as to how the base is assembled. I most certainly do not want to destroy the antenna trying to take it apart.
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I have gone back and looked at my Tecsun AN-200 and I believe it has an issue. I can not find any continuity on any of the Ant Output connector pins. I tested it with an LCR meter, a multimeter and a spectrum analyzer and nothing. Disassembly is most likely imminent. I will have to go back and study all of the pictures to see if there are any clues as to how the base is assembled. I most certainly do not want to destroy the antenna trying to take it apart.
Yeah, I seem having the similar problem with my AN200. As you described, my AN200 also looks very flimsy and the only way to open it seem to by getting something flat screw driver like tool, but the width of the blade fits nicely to the groove of the plastic casing, and pry it open = haven't tried yet. It seems very easy to crack and break it.
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After reading all the posts again, and doing some research, I feel that best option I could try out is,
1. Phased antenna setup with 2x separate active loops (I do need another Wellbrooks or MLA30 and MFJ-1026 or the Chinese QRM Eliminator)
2. WOG (Wire on the ground? Get a drum of wire of 200m long, and just spread out along the garden fence and on the ground going along the fence and coming back making many layers of the wire on the ground), or making it into a loop? = This might give good DX reception? This is something that I have never tried before.
I have come across a few Radio and SWL blogs describing this type of antenna for good LF RX performance. But I was wondering, if the wire is lying on the ground, doe it not pick up the ground noise? http://www.kk5jy.net/LoG/
This one is a loop, but looks interesting and the blogger says that it works very well on MW TADXing.
http://www.ve1zac.com/A%20New%20Homebrew%20Magnetic%20Receive%20Loop%20at%20VE1ZAC.htm
I wonder what your thoughts are on these options, and would be interested to hear especially if any one has been / is using this type of antenna on MW DXing, and reviews on them.
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There are fundamental differences in a BoG versus LoG.
The biggest being a beverage-on-ground can be unidirectional if long enough and properly terminated. It is a traveling wave antenna. More info:
https://en.wikipedia.org/wiki/Beverage_antenna
The loop-on-ground is largely omnidirectional. To be pedantic, it can be fed to have some directionality, but it is not enough front-to-back to make a significant difference in most cases.
Both of these antennas are designed for optimizing the signal-to-noise ratio, otherwise they can trend towards substantial negative gain. A receiver with good dynamic range, plus potentially adding an inline preamp, are potential requirements.
I have used an 148' LoG constructed in a "shielded" format from RG-6 coax for quite a few years now. It works on MW, but it has no directivity, so many frequencies are a jumble of stations at night. Not exactly ideal. Of note, it also works for longwave BCB broadcasters when DX permits.
Another prospect is simply a longwire antenna on the ground. It will be bidirectional off the ends assuming it is fed at one end and not terminated on the far end; plus long enough. Think length in terms of multiple wavelengths. It might be something you could try at a local park, field, or similar.
I used an 148' longwire-on-ground antenna on HF for several years before deploying the LoG. It did have some bi-directional directivity, but again, only where it was like twice or more the received frequency's wavelength. Otherwise it as largely omnidirectional below a wavelength or so.
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Yes, directivity seems critical factor in MW DX antennas. Because usually MWDX signals tend to get buried under the strong local or nation wide AM Tx signals.
But then I am not sure how MWDXers with the vertical antennas cope or manage the QRMs.
A couple of questions for you. When you say "Longwire not terminated at the other end" - then how does it then left? Just free on the ground not connected to anything? What do you mean by "terminated"
You have a "Shielded" loop. How is it different from unshielded in its performance. What does the "Shielding" antenna does for you?
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Basically just a longwire antenna on the ground.
Radio --> Coax --> Transformer --> Longwire
|
Ground
The wire lays flat on the ground. You can start with usual longwire lengths, though putting the wire on the ground is going to detune the wire, so it is not critical IMO. For mediumwave, put as much as wire in a straight line as possible in the direction of interest. YMMV on the transformer. I have run longwire-on-ground antennas before without a transformer when common mode noise was not an issue or a concern.
By termination, I mean the far end of a beverage-style antenna. One end of the wire is fed by coax via a transformer. The other end is "terminated" to a ground rod and/or radials via a resistor. Note one side of the transformer is grounded, too. Actual technical aspects aside, think of the wire as being one side and the ground (earth) as being the other side of a "loop."
Radio --> Coax --> Transformer --> Beverage Wire --> Resistor
| |
Ground Ground
About the "shielded" loop, the typical claim is helping "shield" against near-field noise. The reality is more like the design *might* help balance the currents in the loop, and a better balanced loop *might* fair better with limiting common-mode noise from the coax. Usual YMMV stuff. I built mine as "shielded" due to having lots of RG-6 coax available; not for much technical reason.
More info on magnetic loop design and feeding here:
https://w8ji.com/magnetic_receiving_loops.htm
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Great info !! Thanks.
Yeah, I think it seems easy and simple antenna to put down (not up :D) , and would suit my garden pretty well.
If it performs well for TA MW DXing, that would be fantastic.
For directivity, so far the standard Active Loop such as MLA30 or Wellbrook seem most directional.
To increase the DX pulling power of Active Loops, perhaps some sort of Phasing would work?
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Do you have the space for wire on the ground at mediumwave frequencies? Note it will need to be multiple wavelengths to have any directivity.
The upper end of MW is 175 meters. Figure like 1.5x to 2x that to get any meaningful directivity, so around 1000' to 1500' or so of wire, which is similar to an 160m amateur radio beverage.
The bigger issue is the lower range of the band. That is more like 565 meters. That would be pushing 1/2 to 3/4 of a mile. o.0
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If we are back to the small backyard, what other low-frequency receiving antennas have you considered? If you do not mind building one, a pennant or a flag antenna might be worth considering.
https://www.qsl.net/wa1ion/index.html
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You already have a Wellbrook loop, right? Being straightforward, that might be hard to beat for a single antenna setup in a small yard. So you have an excellent place to start IMO.
Phasing *might* help assuming your predominate noise or interference source is largely from a single direction. I would not buy a second Wellbrook for phasing before investigating other options if trying an antenna phaser. Many find a basic longwire or small wire loop work fine enough for the noise source antenna.
I suppose the bigger issue is a phasing unit with MW support. You can build one, or modify a MFJ model. Otherwise, you likely are looking at serious money, for example the DXE NCC-2. o.0 At $850+, think I could listen to WebSDRs instead. ;)
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Let us see what you can do to maybe improve your existing loop before running down to the hardware store for a mile of copperweld wire. How is the receiver grounded? Could you describe your antenna grounding configuration? What type of coax are you using? Are you running chokes on the feedline? How is the feedline routed?
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Yeah, my yard is only 25 x 25 meters, which is not great. Even that is too optimistic size, because there are plants and sheds and storage boxes dotted around in the yard. So my plan was to run wire all along the fence, and then when it reached to the end, turn back do another run, and do a few runs in layer just to get the length spread out. It will not give any directivity, or maybe it will I am not sure. I was really looking to be lucky, but luck is scarce thing when needing it.
But it is just a little project to try when I have absolutely nothing to do but kill time one day or weekend just for testing.
But you are right, I think Flag or Pedant antenna seems really getting sworn by many MW DXers. The thing I am not sure about these type antenna is that, it is not easily rotatable or moveable once set up. And if they can, then it would be hassle to move or turn all the time when you want different direction for incoming signals. So, I might be actually making a smaller mini version of Flag, and set it up on a stand with wheels, so it could easily be turned around. Still would imagine it would be hassle to run out to turn it when trying to listen some radio at night. So, yes, this is another project in the list.
And you are right. The Wellbrook and MLA30 are actually quite decent Active Loops, which work fine. I was keep looking into making them more DX hungry antennas, so they will pull weaker and more interesting TA DX or rare DX etc.
Phasing loops - I read it on the blogs, and know it utilises usually MFJ-1026 or some QRM eliminator, but not fully understand how they exactly work. And of course, I don't wanna spend lots of money for the hardware, so I will need to read or watch the youtube videos on this for learning more about it. There seems other ways to increase RX antenna gains by stacking or lining up the parasitic elements just like multi element Quads or Yagi antennas in ham radio. Again, I am not sure how it works, and implement it properly, so that it will work nicely.
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For my current set up, I am mostly using MLA30 and Wellbrook Loop antenna. I also have a copy of PA0 mini whip too. I have a long wire in the garden, but it is not currently used. It is just random length of wire of about 40-50 meters which goes round the fence. The wire directly comes into the room via the window, and it goes into the back of my Yaesu FRT7700 ATU, and the coax from the 7700 goes into 3 way antenna switch 2 of them is occupied by the Active Loops, and to my radios.
I also have a washing line (insulated copper wire actually) which is about 20 meter long forming a loop in delta around the 3 metal poles in the ground. The wire is then wound on one of the metal pole in the ground for magnetic connection to the ground, and then it comes into the radio room via the window, then to the FRT7700 Earth connection. The FRT7700 has suspected short or connection problem on the output wire, which I must look into before it is set inline again.
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If the fence completely encloses an area, you might try a horizontal loop. Nothing for directivity, but it might make for an interesting low-frequency antenna experiment.
Also I know it is not going to do much for your desired MW DX, but a loop-on-ground in your space might be interesting for improving MW to mid-HF regional listening if that is something you might want. It looks like you might able to do 250' to 300' total in a square or similar configuration. I would be tempted to experiment by tossing out the wire and connecting it straight to coax without a transformer or preamp. If it does not work in some beneficial way, you just pickup the wire and try something else. :)
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About the grounding, the reason I ask is that I am wondering about common-mode and similar noise. I am curious if you have a high noise floor, and if so, what we might can do to help mitigate it. For example, grounding your feedlines and applying RF chokes *might* knock down some noise to further improve the signal-to-noise ratio (SNR).
Try this during the day. Tune to a open MW frequency. What is your S reading without an antenna connected, and then with the antenna connected?
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Yes, we have 3 fences 2x are hedge plants, and 1x is wooden fence. I tried a horizontal delta loop one time, and as you said, it had no directivity at all. I was receiving multiple stations on the same frequencies often.
I will definitely try a wire thrown on the ground straight connected to a coax just for testing. If it didn't work, always can change it to something else.
I do have a few RF chokes and 9:1 baluns and also 4:1 balun. Whenever I put up a new antenna, I would try these chokes and baluns. If it helps with the RX, then I tend to leave them on. If not, take off, and just run the antenna. RFI and QRN, it is not too bad, and sporadic here.
I just saw this Phased Array antenna presentation, and found it interesting.
https://slideplayer.com/slide/17837705/
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I have been thinking about smaller outdoor antennas with possible directivity down into mediumwave and having relatively simple construction to save on time and costs.
Start with an inverted U, then add termination towards the direction of interest. That is an EWE antenna!
http://www.dxing.info/equipment/ewe.dx
http://f8afc.weebly.com/full-size-ewe.html
http://www.radiodx.com/articles/technical/antennas/it-had-to-be-ewe/
You probably even could fit two or three EWE antennas in your space for multiple directions.
No guarantee it would outperform your existing Wellbrook loop, but an EWE is unidirectional unlike a bidirectional loop, which could help if you need more front-to-back separation in a particular direction.
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Great links, thanks !!
How would you compare EWE antennas with Flags?
How are they different? First impression from the diagrams tells me that
EWE is grounded at both ends, and Flags look like a type of Loop.
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The flag and pennant antennas are related to the EWE. :)
The EWE uses earth to complete its "loop," while the other two use lower wires to complete their loops.
A flag or pennant theoretically should have better directivity and maybe even gain compared to an EWE.
The thing about the EWE is it being earth terminated, which I suspect might help more with local noise versus a raised loop. YMMV, of course.
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Some nice options although one of those links showed the BALUN constructed from a MIX 43 ferrite core. I would not use a MIX 43 core. This is a Nickel-zinc (NiZn) ferrite core with a frequency range of 2 MHz to several hundred MHz. I would use a Manganese-zinc (MnZn) ferrite core, I.E MIX 31, 73 and 75. A MIX 31 is good for 1 MHz - 300 MHz and a MIX 75/J is good from 150 KHz - 10 MHz. MIX 31 cores are common and readily available.
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Great info. Thanks !!
Came across this old post on MLA30, and also found quite interesting.
https://www.hfunderground.com/board/index.php?topic=59386.45
Modify MLA30 with a smaller loop, and attach it to the larger loop for magnetically coupling, and tune the larger loop with
a variable capacitor? Problem with this type of modification would be that, it will not be for outdoor operation at all. Indoor use only?
What about possibility of all the RFI and noise pick up in the room?
How has it been working for MW DX?
Gosh I am in the thread too. Totally forgot about that :D
That was the time before I got my MLA30.
At the time, I was not sure if MLA30 was a toy or real antenna :))
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You can remote tune a variable capacitor, but starting with a MLA-30 as a coupling loop is not ideal IMO.
Being realistic, while there are much worse MW/HF antennas than the MLA-30, its design relies upon a single two-stage video amp. That is far from ideal for signal-to-noise ratio (SNR), which is what you are going to need to optimize for pulling out stations at the noise floor.
Your tuned loop is a good idea. Make it passive a you can add a preamp later if needed. As noted, the loop can even be remotely tuned outside. You do not even an expensive vacuum varicap since you will not be transmitting. Copper pipe, the proper range varicap, a stepper motor, and an inside control for the stepper. It can be homebrewed assuming you do not mind a little soldering.
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Good point on MLA30, and DIY mods.
It is just I saw the old thread about MLA30, and one of the poster showed his modded MLA30 with the extra larger element magnetically coupling to the MLA30, and also tuning the larger element with variable cap.
He seems very pleased with the increased performance on DXing with the mods, and I was wondering about the increased performance on MLA30 DX capabilities after the mod. As you say, I would have been doubtful to see the active antenna coupled to a larger element loop for possible overloading.
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Received my phasing unit from Ukraine.
https://www.ebay.com/itm/284239070097
Usually I have a moderately low local noise floor anyway, so I have been using it more for peaking and nulling signals instead of local noise. IOW, another radio toy with knobs to turn. :)
It rolls off into MW, but I have found usable phasing with my antennas down to approximately 1000KHz or so, at least for strong signals. YMMV for weak signals, especially as frequency decreases.
I have been phasing my 31' vertical against my 148' LoG, and the setup can help separate some overlapping MW stations. For a test I am currently listening to music on 1110 by significantly phasing out WBT from North Carolina. It is not perfect, but it can help turn a jumble of stations into something listenable. Thing is it might not always be the specific station you want to peak or null out from the two or more present. ;)
Two matching antennas would be preferable for the type of phasing I am doing, or maybe even three with the center antenna grounded. Not sure I would want to bother deploying another 31' vertical with a ground radial field, but I might toss out another LoG sometime. Alternatively, I have an affordable active vertical collecting dust, so I could consider ordering another to deploy a pair. Decisions for another day IMO.
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Quick demo of the 1110AM station. You can hear WBT mixing into the music with the phasing unit off. Also added receiver attenuation to hopefully drop the now much weaker WBT towards or even into the noise floor.
https://youtu.be/SgkZhl0IrKE
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Thanks for sharing. It seems to give a nice null. I'm going to have to think about one of these.
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Welcome. :)
Here is the flip-side of the above. Nulling the music on 1110 to hear Coast to Coast AM on WBT.
https://youtu.be/yK13MTGLTKU
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That is very nice. I like it. It makes a world of difference. With all of the antennae options alpard has this would probably greatly enhance his MWDX reception. It probably doesn’t even have to be identical antennae. We still use similar technology in direction finding where there is a centre whip (omni) and a bunch of directed antennae pointing at the various compass headings. You null the directors against the whip until the signal disappears. That null represents the direction in which the signal is emanating from.
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Yeah, matching antennas are not a requirement, especially if using phasing for local noise reduction. I was surprised my vertical and LoG was able to achieve such results given their vastly different characteristics.
Otherwise I was thinking more about using phasing to help steer an antenna array. Ideally that would be two similar antennas with the same polarization and similar impedance characteristics. Staggered parallel beverages, two verticals, etc.
Active antennas typically have wide bandwidth (low Q) and hopefully somewhat stable broadband impedances. Since I would be doing the project on the cheap, I already have one the following miniwhips on a shelf doing nothing and could order another:
https://www.ebay.com/itm/222469570201
I will think about it. In the meantime I might try phasing a couple of simple wire verticals or whatever if/when I feel like deploying them.
A three vertical array for additional enhancement might be possible as well. Probably phase the two outer verticals and ground the center vertical to the radial field. YMMV.
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Great info, thanks.
I have been working on decorating my radio room, and all the radios and antennas are offline for the time being.
Hopefully it will not be too long until it will all get finished and get back on rxing soon.
Working on the walls and ceilings of rooms with plaster can be very tough job taking long time for a lone DIYer :(
And then it will need to get sanded, and painted :(
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Ordered a second active miniwhip for further adventures in antenna phasing.
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It would be interesting to compare the performance for MWDX between Flag Antennas vs. Phased Active Loop.
I am on the way to set up a DIY flag for MW and HFLF soon in the garden in the near future.
Phased Active Loop also sounds interesting, but having to buy a new phasing tuner box puts me off, as it will add into the extra expenses.
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I received a couple of the <2GHz 60dB preamps floating around Amazon, eBay, etc. It is basically a 2-chip cascaded version of the similar inexpensive 30dB preamps.
At first flance I suspect the listed upper voltage limit could be incorrect. 12v probably will not damage them, as I have ran that through the older 1-chip 30dB preamps for short periods, but most of these cheap MMIC-based preamps without voltage regulators likely are rated for more like 4-7 volts to optimize the noise factor.
Anyway, having upwards of ~60dB gain might prove interesting if deploying a high-loss antenna designed for SNR like some of the designs we have discussed here.... assuming the local noise floor is low, the preamp noise factor is not ridiculous, and there is a decent impedance match on both sides of the preamp.
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It is definitly the principle behind the mini-whip antenna. PA0RDT design documents are open source from the author. Pa0nhc has done a very good job at explaining this in a youtube video. His page also includes the Pa0nhc active wideband receiving loop 15 kHz - 30 MHz and the pa0nhc 80m-20m Symmetrical dipole antenna with coax END feed. Don't forget to check out the section on common mode chokes.
http://www.pa0nhc.nl/ (http://www.pa0nhc.nl/)
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True enough, though the preamp in mini-whips tend to pull double duty as both a matching device and gain amplifier. Someday I might actually try a VNA plot of a like 6" strip on HF and lower, though I already can imagine the extreme loading characteristics.
Most of these cheap eBay preamp boards appear to be MMIC-based chips. I was looking at the INA-02184 for a potentially close match to the 60dB boards I received. Actually probably more like clone chips of an INA-02184 or similar MMIC amp, but anyway.
https://www.qsl.net/n9zia/metricom/ina02184.pdf
The gain and noise factor profiles are rather flat under ~300MHz. Rated voltage max also is 7v, which also seems rather typical for these cheap MMIC amps despite sellers claiming 12v. ?! Yeah, 12v might slam the gain, but the NF tends to improve at lower voltages as many of us have already found. No wonder.
I had been using 9v batteries for temporary deployments of the single-chip 30dB preamp model, but think I will drop voltage further down in future testing of both single- and two-chip models.
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Over the years I have tried to switch everything over to Mini-Circuits components (splitters, amps). I am a big fan of their products and there is no shortage of them on ebay. They are a prime supplier of components to the military comms equipment manufacturers. You just need to be persistent and patient on ebay to pick something up at a decent price. For example, there are currently some Mini-Circuits ZFL-1000LN 0.1-1000MHz SMA RF Low Noise Amplifiers (20dB) available for $75.00. A little bit on the high side, but like I said, you just need to keep an eye out for a bargain. I have also found that the Mini-Circuits chip baluns have the best specs out there so far.
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20+ years ago I likely would have been there with ya' regarding hardware. :)
Radio is a part-time hobby for me these days, with HF as my only significant particular interest. That is before even factoring costs versus diminishing content and increasing noise floors; both local and environmental.
Admittedly, at VHF and above I too would be more inclined to spend money on better hardware. Just not much that interests me up there.
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I purchased the new RTL-SDR L band patch antenna last month so this one is my next project.
https://www.rtl-sdr.com/two-reviews-of-our-new-l-band-patch-antenna-stock-update/ (https://www.rtl-sdr.com/two-reviews-of-our-new-l-band-patch-antenna-stock-update/)
As with yourself, I am primarily DC to 30 MHz and 220 to 400 MHz (UHF MIL and SATCOM). I ventured into ADS-B (1090) in 2018. ADS-B is Automatic Dependent Surveillance - Broadcast and are ground & aircraft transponders including flight data. Essentially, the high frequency version of HF-DL or ACARS. This is what the airspace around my house looked like in September 2019.
(http://www.milspec.ca/board/img/2019-08-30_182414.png)
Now I am curious to look at the GPS band, INMARSAT and Iridium space with the SDR.
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I thought about ADS-B back when the RTL-SDR landed. I just never got around to it. Some day perhaps.
I largely dropped out of the UHF scene when public services and similar went digital.
Be careful or next you might have a Ku dish on a motorized mount…. and looking for somewhere to put the C-band. ;D
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Well, a Ku antenna kind of already exist in the front of the house but it's busy receiving DTH satellite TV service. There are some interesting Ku LNBs mounted in tin cans which work for antennae in that band. For UHF, I only listen to the military stuff in the 220 to 400 MHz band, including the UHF SATCOM.
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Not sure when he started offering them, but ra0sms now has a flag/pennant antenna kit on eBay. :)
https://www.ebay.com/itm/201553084711
Same but with an 1-4MHz bandpass filter.
https://www.ebay.com/itm/202274557903
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My second active mini-whip arrived. Now to take a portable to the backyard and hopefully find a couple of relatively RFI quiet spots to place them.
I am a little more concerned about placement than usual as small active verticals are essentially e-field probes. Even a foot or two difference can change coupling to local noise fields.
Get them deployed, then see how well my phasing unit can effectively utilize the small array.
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JTA still swears on using the W.O.G., (Wire On Ground.), for RX'ing LF and MW super quiet signals. Hopefully, that may happen this Fall since, thanks, (Or no thanks!), to Biden, all gas line projects around the property here have been put on either a prolonged, or indefinite, hold. I have hundreds of feet of trashed RG-11 rigid coax, with tough PVC outer jacket. Useless as regular coax, but that solid aluminum outer conductor could make for a kick-ass antenna. Stay tuned!!!!!!
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I used an 148' run of RG-6 as a wire-on-ground for years. Fed the center at one end, and shorted the other end back to the shield. I am not sure there was any improvement over just a piece of wire, but I had lots of coax going unused.
Fed it straight, with an 1:1, and with a 4:1. Did not seem to make much difference IMO. I went with a straight feed. No common mode choke at the feedpoint, either, so the feedline shield was the other part of the antenna. Worked okay enough for my purposes from MW through mid-HF at the time.
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As promissed, here are a couple of SDRuno screen shots with the RTL-SDR L band patch antenna connected to the RSPduo SDR which I mentioned in reply #90. No issues with reception, and this is with the antenna sitting inside on the window sill.
(http://www.milspec.ca/board/img/2021-05-31_193320.png)
(http://www.milspec.ca/board/img/2021-05-31_193536.png)
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Pretty nice for inside. :)
BTW, I was able to quote and view the pics, though note they are not showing up here at HFU. The host might be blocking them at third-party sites.
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Deployed one active miniwhip. Have another one to go. I am using a PA0NHC-derived design built with SMD parts via the Transverters-Store.
https://www.ebay.com/itm/222469570201
I did not bother much with selecting a spot. I just put it at the back lot line away from the house. Mast is a 10.5' fence top rail buried about 3' in the ground. I might extend the height later, but I have to take some care due to tropical weather. I really not too interested in installing guylines, either.
The antenna is working. I am listening to 20m SSB contacts at 0428z ranging from California to Russia. Noise floor on 20m is averaging under -120dB according to my AirSpy HF+ Discovery. Not bad IMO. :)
I am not even using any ferrites on the feedline, and the the coax is only grounded to the base of the mast. It was getting dark outside when finishing up the coax run. I do have a KD9SV RF common mode choke rated for 3000-ohms+ resistance at .5-10MHz back near the receiver.
I intend to ground the antenna at the top of the mast as intended by the design, plus probably install a few ferrites. Maybe tomorrow.
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A quick screenshot of AM BCB. Well, a 725KHz portion of the band to be technical.
https://imgur.com/a/eCcJHWO
Current nighttime mediumwave noise appears to be hovering around -90dB at the bottom of the band to nearly -100dB at the top of the band. From a noise perspective, my community is somewhat rural, but my immediate neighborhood is more like a suburban area.
I am definitely going to need the second active antenna and the phasing unit to sort out the mediumwave jumble. Too bad the phaser only goes down to ~1MHz, but whatever I suppose. I am more of a casual mediumwave listener anyway.
I would do a screenshot comparison with another antenna, like my 148' LoG, though the feedlines for those are across the house. I try to do a comparison at some later time.
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Quickly skimming VLF and lower LW with the active miniwhip, I was able to spot Cutler at 24KHz, Aguada at 40.75KHz, and WWVB at 60KHz.
Rolled by a few beacons in LW. I would say my CW is limited, but it is more like nonexistent without a decoder. Morse code just does not work for me.
NavTex at 518KHz; probably Miami.
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Still running in the background. Been listening to Asian DX on 40m SSB this morning, including currently an op from Papua New Guinea running 100w into whatever loop antenna.
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Now grounded to the top of the mast, too. Did the same thing I did at the bottom of the mast. A couple of F connectors, a female-to-female barrel connector, and a hose clamp. Yeah, it is a mechanical connection, but soldering at the top of a mast with wind blowing (and thunder in the background) did not seem like a fun idea.
Might go back out in a few to add a few snap-on ferrites, though AFAIK, most of the ones I have available currently are for higher frequencies. Whatever, I suppose.
I was also considering adding a few on-ground radials at the bottom of the mast. Like maybe four to eight 9' wires. Still undecided, though.
I will try to deploy the other miniwhip later this week or next, then take a closer look at MW with the phaser inline.
................
Update. A snap-on ferrites added, for whatever they might or might not help. I need to order some more mix 31 or 43 ferrites. I just do not like the price for large ones.
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I was never pleased with my Mini-Whip antennae. One of them works not bad but the other not so well because of its location. They most certainly do not perform like the one at the University of Twente. I'm going to replace one of them with a short vertical of some kind. I just need to design and get around to building it.
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Mine is working about as expected thus far, though I tend to have a low almost rural-like noise floor much of the day and pretty much most nights. Beyond local noise field coupling, area SNR is a big consideration with amplified low-frequency antennas.
Admittedly, RF noise does vary somewhat with neighbors' activities. For example I suspect someone nearby might have a plasma tv, but it is generally intermittent and seems limited to day time hours when present. Even the quite limited noise blanker on my old Kenwood R-2000 usually cleans up most of it, so I tend to just ignore it. Now if it was there all day.... :/
Currently my miniwhip is grounded to a 10.5' mast, with about 3' in the soil.... well, more like sand here. I am thinking about adding a few ground radials to the base of the mast given the local sandy soil. Kirchhoff's first law still applies even to active e-field probe antennas. IIRC, the one at Twente is grounded against a large metal roof. ;)
If interested in perhaps trying another miniwhip in the future, you might find the following document a worthwhile read:
https://www.dst.defence.gov.au/sites/default/files/publications/documents/DST-Group-TR-3522.pdf
Otherwise, speaking of smaller antennas, I find my unamplified 9' vertical can be a decent "general-purpose" antenna for local MW BCB, casual HF, and even local FM BCB. It is a typical CB steel whip with spring section on a mobile window mount, u-bolted to a copper pipe driven in the ground. It has just four 9' ground-mounted radials and a few snap-on ferrites on the feedline.
IIRC, the US Navy once published a study suggesting an unamplified 6' whip was typically more then enough for basic HF reception when contrasted against atmospheric noise. However I am unsure what, if any dedicated ground plane was considered. Might have been grounded to an entire ship, or it might have simply been common mode on the feedline and receiver. YMMV.
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Ack the roof at Twente. If you read their documentation they even mention that the only reason the antenna works so well is because of the large metal roof. Both of my Mini-Whips are this one: https://www.ebay.com/itm/MiniWhip-Active-Antenna-HF-LF-VLF-mini-whip-shortwave-sdr-RX-portable-receiving/332818922997 (https://www.ebay.com/itm/MiniWhip-Active-Antenna-HF-LF-VLF-mini-whip-shortwave-sdr-RX-portable-receiving/332818922997) and are well built. They look identical to yours. I purchased one fully assembled and the second as parts so that I could see how it was built and play with it i the shop. I later installed the antenna in a PVC pipe.
I'm sure you have seen Fundamentals of the MiniWhip antenna: http://www.pa3fwm.nl/technotes/tn07.html (http://www.pa3fwm.nl/technotes/tn07.html) and Grounding of MiniWhip and other active whip antennas: http://www.pa3fwm.nl/technotes/tn09d.html (http://www.pa3fwm.nl/technotes/tn09d.html)
Try moving your ferrites closer to the house. These do not do much at the antenna base. Ferrites at the antenna protect the antenna from becoming a victim of coax noise. This is the typical placement of ferrites when you are transmitting into the antenna. If you want to remove noise picked up by the coax the ferrites are more effective at the receiver. The best way to view this is to think of it as "source" and "victim". In the case of a receiver, the "source" is the coax and the "victim" is the receiver. The entry point to the house is a good place as it removes noise generated by electrical wiring etc ... You would be surprised how noisy wall surfaces can be. Ferrites at both ends are ideal. Mix 77 (100 kHz - 10 MHz) is a good choice or you can slip some mix 77s and mix 31s (1 MHz - 300 MHz) together. All of my ferrites are outside at the entry point and I have a common mode noise choke at the output of the antenna switch. Ferrites are not weather sensitive so no need to seal them etc ... For the Mini-Whip, the coax forms part of the antenna system so it has to be routed away from noise sources.
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Sure enough that is PA0NHC-derived design, too.
Thankfully I have not had much issue with common mode noise ingress on even my cheapest RG-6 feedlines, though I usually have some type of ferrites or chokes on both ends of my various feedlines. There also is the factor of having a concrete-block stucco house. The stucco is applied over wire mesh, and the house is electrically grounded to the rebar in the concrete foundation.
I have KD9SV common mode chokes closer to the receivers on some of my HF receiving feedlines. The model is rated supposedly for 3000-ohms+ common mode resistance at 0.5-10MHz. I suspect mix 73, 75, 77, etc.; but they are potted, so no real idea on my part.
https://www.dxengineering.com/search/brand/kd9sv-products/product-line/kd9sv-products-sv-cmc-common-mode-choke/part-type/hf-receive-antenna-system-devices
IIRC, the only outside antenna I have deployed currently without choke ferrites at the feedpoint is my 31' vertical. It has a 4:1 unun between it and the coax, then back to one of the KD9SV common mode chokes near the receiver end.
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Deployed the second active miniwhip about 40' to 45' from the first one. Took a quick skim on upper mediumwave. So far phasing them can help with noise when tuning a single station. The better test should be tonight to try nulling and peaking simultaneous signals on the same frequency.
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Quick-and-dirty example. I cycle the phasing unit a couple of times. Watch the noise level in the waterfall.
https://www.youtube.com/watch?v=zqYjeREnnJQ
Local MW conditions are extremely rough right now with an elevated noise floor, static crashing, etc.
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Rob, remarkable difference in the noise level. I was also thinking about your grounding. As these types of antennae use the shield / braid from the coax as a counterpoise, perhaps the addition of a real counterpoise vs. a ground at the mast may yield some extra benefits.
Have a look at this article: How to properly install a Mini Whip antenna in an noisy urban environment
https://swling.com/blog/2020/10/how-to-properly-install-a-mini-whip-antenna-in-an-noisy-urban-environment/ (https://swling.com/blog/2020/10/how-to-properly-install-a-mini-whip-antenna-in-an-noisy-urban-environment/)
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Currently the coax feeds are grounded at the top and bottom of the 10.5' masts, with 3' of the masts in the ground and choke ferrites as the coax cables leave the masts.
Elevated counterpoises are out for now due to limited height, but I have thought about adding a few on-ground radials at some point. Alternatively I thought about using metallic guylines for added counterpoises if I ever bother adding another 10.5' section to each mast.
I can listen routinely to signals from the Middle East, interior Asia, Oceania, etc. on HF with just one miniwhip when propagation cooperates.
I am just too close to the tropics for decent mediumwave summertime reception, especially with these active antennas. Elevated noise floor and near constant static crashing. ;)
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Second active miniwhip is way down on gain versus the first one. I should have checked that when deployed, but just noticed it when swapping around feedlines.
I checked impedance at the feedline. It matches the good one, so it is unlikely to be feedline or output stage related.
I will try taking a look at the antenna board later.
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Went ahead and just ordered a replacement antenna board, too.
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I did a couple of very unscientific lab test on one of mine. Essentially, I swept the antenna with a tracking generator / spectrum analyzer. I was curious to see what frequency bands the antenna responded the best to. I will go back and dig out the data and present it later.
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Replacement board arrived. Need to swap it out.
Meanwhile my 31' vertical is offline. Had some trees trimmed, so wondering if they did not run over my feedline or similar. Fun stuff.
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The joys of the hobby. As a side note, I am currently listening to Drunken DJ Radio 6950 USB 0138 UTC 05 JULY 2021 with the Belka-DX and telescopic antenna while sitting in the basement from a location 500 miles North of Toronto, Ontario Canada. The receiver is working like a charm.
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Receiver aside, that is a good demo of what actually good propagation can do. Hopefully conditions will improve further as we progress into the current solar cycle.
I have almost ordered the Belka a few times, but I keep talking myself out of it. I have several portables largely going unused as it is.
Been thinking about the 31' vertical. After resolving whatever the issue is, I might change the feedpoint setup. Right now it has a 4:1 unun to help with high-impedance excursions like around the 20M band where it is near a half-wave vertical, but I know that 4:1 transformation could be hindering performance below 40M where the antenna is already low impedance. A remote preamp might be better, especially for extending low-frequency performance. Decisions.
................
No 31' vertical for my usual Kenwood R-2000 tonight, so I have been experimenting a little.
Listened to an 11m opening via the 18' end-fed vertical, then DX from France on 20m via the 148' LoG.
The interesting part IMO is the preamp. I typically use a MFJ-1020B (~20dB) with that radio if needed, but I am trying an eBay "60dB" preamp since my current upper HF noise floor is rather low. I am not interested enough at the moment to actually measure much of anything, but it probably does deliver like 40dB+ (or more!) of gain at 12v. Naturally, high noise floors need not apply with such ridiculous gain. o.0
I am sure the eBay preamp's noise profile likely is horrible, but I can foresee a few possible uses when the noise floor is already *very low* and wanting extreme gain for a BoG, LoG, or similar.
................
Leaving the inexpensive preamp inline for awhile, but I did move it to the more proper location between the MFJ-1030B and the receiver. The 1030B is back to being a preselector and gain controller if needed.
....And now a 20dB attenautor between the preamp and receiver. Got tired of tweaking the receiver's own attenuator.
Probably will put it back to normal later today. Just playing around until sunrise. Planning to swap out that active antenna board this morning, plus maybe take a quick look at the 31' vertical.
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Combined a few posts. ;)
Swapped out the active antenna board. Quickly tested each active antenna with a Tecsun 310 using a couple of local mediumwave stations for steady groundwave signals. They are about the same. Like 1-2 dBu difference; if that. Yay!
I did note one regional station with a slightly higher dBu difference, but I suspect it is due to the positional differences and/or perhaps the storage building in between where the two antennas are mounted. Basically typical stuff when dealing with active e-field antennas.
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Put the antenna phaser inline. I just do not have enough local noise or the need for nulling for it to do much on HF during the day. I can get a mild gain bump through combining and/or maybe slight directivity, but I have not found it useful as of yet. Maybe it will fair better at night on MW, but otherwise I suspect the two active antennas will feeding two receivers more than feeding the phasing unit. ;)
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With regards to propagation, yes, the SSN has been very high over the past few days. 81 yesterday, which I have not seen in a while. For the mini-whip antennae, I do believe there are all kinds of factors which can affect their performance. I as well use a step attenuator to balance gain vs. noise.
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Sometimes you can change the performance of an active e-field antenna just by moving it a few inches. ;)
Put the Kenwood R-2000 back to normal.
Glanced at the 31' vertical. I straightened some ground-level radials, but otherwise it looked okay. I need to check the antenna-side connectors at the unun. I might have broken one when shaking the fiberglass vertical lose from a nearby limb awhile back.
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Might have found the 31' vertical antenna issue without much effort. Went outside to lay the fiberglass vertical section on the ground for the coming tropical storm. A short jumper wire from the antenna wire to the unun pulled rather easy from its junction. So hopefully an easy fix.
BTW, I assume we have turned this in a chat thread by now. ;D
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Have to love those easy fixes. Chat thread, yup, but with 4,094 reads and no complaints one has to believe there is some degree of experience being gained by some of those readers. It is a hobby after all, one which I have been involved with both personally and professionally for over 40 years --- and as technology changes I am still learning. We have not heard from "alpard" for a little while. I see that his last active date was 2021-05-30.
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The S9v31 is back vertical. Stripped the antenna wire and the jumper to the unun. Twisted the two together. Added a couple of wraps of electrical tape. It is now working. :yay:
I need to properly solder and heat shrink the connection, but it was getting dark outside. Maybe over the weekend.
Also have most of the coax to the two active miniwhips lawn stapled down.
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I have been doing SSTV captures on 20m in recent days, so I am thinking about deploying my S9v18 that has been collecting dust in storage.
Then again a 20m dipole is not exactly a large antenna to deploy, either.
Decisions.... ;)
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Ha ha ... conditions have been excellent late at night for the past week or so, and in a complete inverse of the regular bands. 14 ~ 18 MHz was hot well after 03:00 UTC. Even WWV at 15 MHz was a +20 at 03:00. 3 ~ 6 MHz was dead. A complete inverse. No complaints, it made for some nice high frequency South America and European DX. Even my less than effective mini-whip was hot.
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Right there with ya' on mid- to upper-HF conditions on recent nights. European amateurs on 20m. Asian stations on the 16m band. 11m CB openings, too.
That said, I also still have lots of lower HF broadcast activity, but admittedly much of that is typical regional stuff for me anyway.
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I have a low inverted L MW transmit aerial here which I've being useing for reception recently. Just inductively coupled to a small transistor radio. Nothing fancy. Works great!
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When too much gain presents an issue on MW. Added a SMA 20dB attenuator between the RTL-SDR V3 and NE602 upconverter. It was a quick fix, so I might play with the dB value later.
RTL-SDR V3 + NE602 Upconverter:
https://imgur.com/a/UOA5a5P
RTL-SDR V3 + NE602 Upconverter + 20dB Attenuator:
https://imgur.com/a/cz6luBF
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20dB helps reigns in MW and lower, but 10dB or perhaps no attenuator seems a little better on HF. I suspect adding an attenuator could be helping smooth the impedance match, too.
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No attenuator is acceptable enough on HF for casual listening IMO. Whatever.
Now to get back to my Airspy HF+ Discovery. ;)
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I might move one of the active whips. It have not done a full HF scan, but its noise level on upper HF appears a few dB higher than another one located like 30'-40' away. Another example of positional effects on an e-field antenna.
Then again, the one with higher upper-HF noise has a better noise profile on 20m. Linearity? What linearity? ;)
Dropping down to ~40m seems to be about the same so far.
Naturally, storms are rolling now into the local area.
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I am going to add a counterpoise to one of mine and see what happens. I got a small o-ring clamp at the hardware store this past weekend. I am just going to tighten the clamp and the counterpoise wire to the BNC.
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Take care with placement. AFAIK, counterpoise radials can seriously skew an e-field vertical unless the radials are symmetrically well balanced.
I am considering moving my second active miniwhip closer to the first, then split their feeds to different radio locations in the house. Thankfully I am not dealing with much local RFI, and I can play around with directional phasing later. Moving it also gets the mast out of the edge of my 31' vertical radial field.
About my S9v18 vertical collecting dust, I have ordered an unity voltage gain preamp to eventually deploy it. The circuit is based upon the AD8055 preamp design by W1FV.
http://lists.contesting.com/archives//html/topband/2018-11/msg00029.html
https://www.ebay.com/itm/YCCC-Hi-Z-preamplifier-for-experimenters-and-RX-antenna-system/203459071504
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I have a low inverted L MW transmit aerial here which I've being useing for reception recently. Just inductively coupled to a small transistor radio. Nothing fancy. Works great!
Good stuff. :) Curious, are you inductively coupling with a fixed loop, tuned loop, etc.?
I sometimes plug one my outdoor antennas into a Tecsun AN-200 tuned loop, which in turn is inductively coupled to a portable radio. Naturally the AN-200 losses much circuit Q that way, but there is still enough for a little selectivity.
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I have a low inverted L MW transmit aerial here which I've being useing for reception recently. Just inductively coupled to a small transistor radio. Nothing fancy. Works great!
Good stuff. :) Curious, are you inductively coupling with a fixed loop, tuned loop, etc.?
I sometimes plug one my outdoor antennas into a Tecsun AN-200 tuned loop, which in turn is inductively coupled to a portable radio. Naturally the AN-200 losses much circuit Q that way, but there is still enough for a little selectivity.
The end of the wire aerial goers into a tuning unit. I just place the radio as close to the wire as I can. No tuning. It pulls in a low power pirate that is about 65 miles from me quite well.
If I could figure out how to post a video of it, I would.
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K. :) About vids, you would need to upload them to a host like YouTube or similar, then link them.
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Oh yeah, thinking about antennas. I finally broke down and ordered a remote receiving antenna switch. I am getting tired of managing multiple coax runs.
It an 8-port model with switching control via WiFi. Could be awhile before arriving, though, as it is coming from Russia.
Depending upon network security, I am thinking it might end up on its own isolated WiFi network.
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Rob, I'll be interested to hear about your switch when it arrives. I have been thinking of one as well for the past little while. I even found one that has a balun which converts the RF onto a CAT-5 cable and back out to a connector in the house. This caught my attention because running a piece of CAT-5 or CAT-6 is extremely convenient vs. coax. The telephone company has been doing this over twisted pair for 100+ years, why not radio.
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Here is what I ordered:
https://www.ebay.com/itm/202550852561
https://www.ra0sms.ru/p/remote-antennas-switch-with-wi-fi.html
I purchased his last assembled one listed at eBay, but the switch is based on this kit:
https://www.ebay.com/itm/202550867003
I am not sure if he is going to be assembling anymore for eBay. The assembled version still is listed at a his own online store, but I have never ordered from there.
http://ra0sms-shop.ru/product/remote-rx-antennas-switch-with-wi-fi-interface-hf-hamradio-8-to-1
Otherwise the kit appears rather straightforward. I just did not want to deal with building it.
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I am thinking Chris used ethernet cable for feedline with his crossed loop antenna.
http://www.tarluz.com/copper-network/complete-comparison-table-of-cat5-cat5e-cat6-cat6a-cat7-and-cat8-copper-cable/
Common ethernet cable types are rated typically around 100-ohms impedance up to whatever their maximum design frequencies.
CAT-6a STP (shielded) or higher probably would be better if needing improved EMI/EFI mitigation, plus it can be sourced as outdoor direct burial if needed.
There is a listing for CAT-6a STP 500' direct-burial copper cable on a damaged spool for ~$131 shipped at eBay right now.
Specs aside, I would suggest avoiding unidentified cables due to the risk of copper-clad aluminum wire. CCA can suffice for certain wiring purposes, but it likely would make for horrid feedline IMO.
Yeah, I use stranded CCA hookup wire sometimes, but thankfully my larger Audiopipe 18 and 20 "CCA gauge" rolls have proven usable for my basic purposes like on-ground radials, jumpers, etc. Nothing under any significant stress, tight tolerances, or high voltages.
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I am thinking Chris used ethernet cable for feedline with his crossed loop antenna.
http://www.tarluz.com/copper-network/complete-comparison-table-of-cat5-cat5e-cat6-cat6a-cat7-and-cat8-copper-cable/
Common ethernet cable types are rated typically around 100-ohms impedance up to whatever their maximum design frequencies.
Yes, the original LZ1AQ amp uses ethernet cable. One pair is for the signal, the other wires are used for power and control signals. The N4CY version I am using now uses a regular coax feed with DC power on the center conductor.
I want to get back to playing around with ethernet for antenna feedlines.
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Now grounded to the top of the mast, too. Did the same thing I did at the bottom of the mast. o
Did grounding help with the mini whip?
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Chris, thanks for the clarification. :)
Did grounding help with the mini whip?
I already had the miniwhip grounded to the base of the mast. I added another ground point to the top of the mast, which is where it really should have been grounded to start. I was just building it in stages.
Anyway, yeah, grounding an active miniwhip is incredibly important to the antenna performance. Think of the ground as the other "half" of the antenna just like a basic half-wave dipole has two "sides."
If you do not provide a decent RF ground path, then the miniwhip primarily uses your coaxial feedline as its RF ground via common mode. Sometimes that works okay, but for many deployments that introduces increased EMI/RFI in to the situation. A miniwhip relies on a high-gain preamp for its performance, and that is already putting an increased noise profile into the receive path. Also there is the issue of a miniwhip being an e-field antenna, thus being particularly susceptible to local EMI/RFI coupling. You want to limit noise ingress as much as possible. Improving RF grounding and feedline decoupling are good places to start.
The 10.5' masts for my active whips have provided enough RF grounding for my particular deployment and casual listening purposes IMO. However, going to an extreme, look at what the popular Twente WebSDR does. Its active minwhip if RF grounded to a large metal roof of a building at 20 meters height above ground. o.0
http://websdr.ewi.utwente.nl:8901/qrt.html
http://www.pa3fwm.nl/technotes/tn09d.html
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YCCC-style preamp deployed on the 31' vertical. The antenna is little large for the intended preamp design, plus I bonded the RF ground to my existing sixteen ~31' ground radials instead of just a ground rod as intended by the designer. In other words it is dealing with more input gain than intended, though it is handling it okay thus far.
I noted a few trivial harmonics from whatever flamethrowers, but just attenuation usually knocked it down, and it is something I deal occasionally with even without a preamp. Radio Rebelde and Radio Marti might as well be locals with their over S9+60 signals at times. o.0
Gain is slightly up in some bands and slightly down in others. I figured that might happen. It is not a high-gain preamp, but instead it is designed to create a ~75-ohm feedpoint…. technically for a multi-antenna phased array. Just one antenna here. Anyway.
I get why the array design suggests a moderate-gain preamp after the phasing unit. No big deal IMO, as I usually have a MFJ-1020B in-line with that antenna if really needed. I might look into a better preamp later.
The biggest plus I have noted thus far is an improved noise floor, especially at lower HF and MW frequencies. Signal levels aside, actual SNR on lower frequencies seems better than even my 148' LoG, though I would need to hookup a SDR to get actual numbers.
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SNR is good, but signal levels have dropped considerable on 80m and 160m. Booming signals are now like S1, and many are not even moving the S meter.
Normally I could not care less about S readings, but my primary R-2000 receiver is only so sensitive.
The MFJ-1020B is great for dealing with a significant mismatch on a highly negative-gain antenna, like with my LoG if (rarely) needed. However it is not too great with this YCCC preamp setup, and constant retuning a preselector is not my idea of fun.
I am not spending $150+ on a decent preamp for mostly casual listening, and I do not feel much like building one, so I ordered a Noolec HF preamp. I have no idea what chip it is using, but at least it supports multiple power feed options and has a RF limiter circuit. I will try it inline near the receiver, since coax loss on 80/160 is minimal. If it looks okay, I can derive 5v from the 12v bias tee of the YCCC and place it near the antenna feedpoint sometime.
If I do not like the results, I likely will be putting the 4:1 unun back at the 31' vertical feedpoint. Maybe then later deploy the YCCC as designed with a smaller vertical and just a ground rod as I have a S9v18 collecting dust. That probably will need a second preamp as well, but at least the YCCC input side will have a match and input gain much closer to what it expects.
BTW, about MW in particular, the YCCC appears to excel there. I only took a quick skim, but I could tell signal levels were improved with no perceived loss in SNR. LW looked good as well, including noting several NDBs. I would leave the setup as is if I wanted only a MW/LW solution, as no doubt the YCCC cleans up the match down there, especially compared to my usual 4:1 unun setup at such low frequencies.
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Looks like the YCCC unity-gain feedpoint preamp is staying on the 31' vertical for awhile longer. The Nooelec HF preamp picked up the gain as expected. I am powering it via an Apple USB 5v power supply.
I know there has to be a SNR change, but so far it is not glaringly noticeable, so whatever for now. Largely just improved signal levels, which the setup needed with my usual Kenwood R-2000 receiver IMO. Currently listening to a 75m QSO.
That said, the 4:1 unun might back over the weekend if I feel like bothering with it.
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Rob, good to know about the Nooelec preamp. I was thinking of getting one on my next order just to play with. If you reacall, way back towards the start of this post, I had mentioned that I have Nooelec Flamingo filters and that I was, and still am, happy with them. I have both the AM and FM in series with the input to the SDR.
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The Nooelec HF preamp does seem decent for the price. It is hardly high-end, but it does have RF shielding and a purported RF limiter. I am not testing the limiter. ;p
The 4:1 unun is back on the 31' vertical. The YCCC preamp probably helped best around low MW down into LW, and that makes sense given the impedance mismatches alone. However, as noted earlier, it nosedived my low-HF signals compared to the 4:1 unun. So out it goes, and back to the known setup.
I am hoping to one day soon deploy the WiFi-enabled antenna switch. It should help clean up some of my multiple feedlines, or just allow me to deploy yet more antennas. ;) I know my deployed 9' vertical is not connected to anything right now, plus I have an S9v18, a MLA-30 loop, a Chinesium miniwhip, a FM BCB crossed dipole, a small discone, etc. collecting dust and needing deployed.
Also I have a Radio Shack version of an Antron 99 in storage. Alternatively, I have a couple of 11m/10m mobile verticals that would suffice for an easy horizontal dipole on a tripod, too. Either way I have been thinking about making a portable setup for a little 11m SSB talking at the beach if/when it over cools down.
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It is hardly a strong signal, but FIS 332KHz from Key West is copyable tonight on the Kenwood R-2000 via the 31' vertical. No preamp or preselector needed.
Heard some others. Just happens FIS is close enough and powerful enough to be a quick catch here.
That said, it is not a copy on the 148' LoG. Hmmm. Might have to do a VNA sweep there to see if something is wrong. Admittedly, it has been deployed for years and is almost more like a loop-in-ground these days.
Popped the Nooelec HF preamp in line with the 31' vertical to do a quick check for overload. FIS still was there, but I did use a 10dB attenuator at its input to cleanup up a little splatter from whatever MW or tropical-band flamethrower. Not bad for a basic $25 preamp IMO.
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That said, it is not a copy on the 148' LoG. Hmmm. Might have to do a VNA sweep there to see if something is wrong. Admittedly, it has been deployed for years and is almost more like a loop-in-ground these days.
Remember that LoG and BoG antennas need to sit ON GROUND and not under it. When they get subsumed into the ground, performance suffers. See Figure 39 here:
https://rudys.typepad.com/files/qexjul-aug-2016-bog.pdf
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Yeah I know. Here is it more like accumulating pine needles and shifting sand. I do not bother cleaning them off since it is in the edge of a wooded area. I might eventually get around to taking the leaf blower to it.
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I know greyline, but still, the MUF here has been falling *quick* in recent nights. Earlier tonight I was listening easily to 16m broadcasts from Asia to way after dark, but now even Cuba on 13460 in the 22m band is a rough copy as the local estimated MUF is down already to 12MHz. I suspect it will drop towards or into single-digit MHz in another hour to two.
Down to 11MHz here. Part of NA is down in to single digits.
Getting there. Floating around 10-11MHz. Part of interior NA is down to 8MHz.
BTW, a link for those following along:
https://prop.kc2g.com/
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Rob,
Thanks for the prop link. I didn't have that one in my collection.
Same for Nooelec pre-amp. I'll put it on the list of items to order. I can sympathize with the use of the 10dB attenuator. I had the same issue with my Wellbrook loop. That is why I replaced my 10dB step attenuator with the Flamingo filters. They are now in-line all the time to attenuate the AM and FM bands by +/- 30dB.
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Welcome. I find the estimated values to often be close enough for casual skimming. I might fair 1-2MHz above the estimate if referencing broadcast SWL stations running substantial power and/or directional arrays.
Thankfully I do not deal with much overload here. The stations I mentioned are a couple of my worst offenders in the HF spectrum, and especially with me being right in the path of Radio Marti beaming into Cuba. I would not be surprised if Radio Rebelde is more like transmitter splatter and harmonics, either. The audio is often so compressed to have practically no dynamics and headroom left. I can almost imagine the final stage tubes singing and echoing along now. o.0
Now there is an area in Canada with an estimated MUF of 1MHz. Outlier perhaps, as I am not seeing any related space weather reports. Hmmm.
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Looking over my recent loggings in the shortwave section, I think my 31' vertical is back to working okay. :)
I *might* change out its ground radials if/when cooler weather arrives. Right now there are sixteen ~31' radials on the ground, but they are built with like "18-gauge" CCA speaker wire. The CCA seems to have held up to quick visual checks so far, but I have not run actual conductivity checks. I would prefer copper THHN or similar.
An alternative idea would be raising the vertical and using a couple or so elevated radials, though I am concerned it might have to be guyed unless I want to drop it each time a tropical weather system arrives.
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I am trying to correlate the figures / prediction from https://prop.kc2g.com/ (https://prop.kc2g.com/) and it is not working for me right now. Based on the variety of other propagation tools that I use it seems skewed.
Here are the screen shots from the site compared to Collins PropMan, HamCap and VOACAP. All 3 of these track pretty close on a point-to-point circuit between Toronto and Boulder. I tweak these for worst case scenario, 100 Watts and 0dB gain on a dipole @ 35 feet off the ground. Even with that, the FOT does not come close to what I see on the website. The MUF seems pretty close. Something to further look into on a rainy day.
(http://www.milspec.ca/board/img/2021-10-05_154717.png)
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About all I use it to do is for a quick check of MUF. Basically to get an idea of what the bands are going to look like for the next hour or few.
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MW is thus far active tonight. I should have adjusted the waterfall contrast, but anyway, ya' should get the point. Antenna is one of my active miniwhips.
(https://i.imgur.com/JgQpdw9.jpg)
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I live in an RF rich area. Here is the spectrum from the end-fed longwire antenna plus the in-line 35 dB Flamingo AM notch filter.
(http://www.milspec.ca/board/img/2021-10-29_231724.png)
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Playing around with the Airspy HF+ SDR setup tonight since I am in the den away from my usual radios.
I already had a KD9SV SV-CMC choke just upstream of my bias tee, plus some snap-on chokes at the mast base of the active minwhip antenna. I just added six turns of RG-316 on a Fair-Rite likely mix 31 or 43 snap-on choke between the bias tee and SDR. I did not measure actual numbers, as the noise floor was already decent IMO, but the waterfall looks a little cleaner in quick skim.
I suspect it was slight noise from the bias tee, as it is powered currently by a wall-wart. The wall-wart is a linear transformer, but it probably could use extra filtering. I have bias tees to which I added filtering caps, but I think this one is still stock.
I might change the bias tee for a filtered one and go back to a regulated linear PSU later tonight. I was trying to clean up some of the clutter by ditching the bigger PSU, but I suppose "oh well."
Went ahead with the components swap to a bias tee with filter caps and a regulated linear 13.8v PSU. Probably not much difference, at least regarding the HF noise floor, but ideally it should be the technically "better" configuration. Anyway.
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I have been running an HP 6216A power supply instead of wall warts. The 6216A or the 6215A series are nice compact, lightweight units and are reasonably priced on eBay. They are also dirt simple to repair should they ever require any service. Nice old fashion transformer power supply design with ordinary components.
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I would not mind an used programmable lab power supply, but shipping for the heavy units usually ends up being quite expensive, plus assuming a seller even bothers to actually check it beyond a power-on test. o.0
Like when I once scored a new Eaton 5PX 1500 UPS on eBay for under $50 with free pickup from an area electronics recycler. It was an ~$1000 UPS, but I suspect few people bid due to how shipping costs were calculated and listed in the auction.
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Hi Rob,
The 6216A measures all but 8" x 6" (and that 8" including extrusion for the knobs and the heat sink). It is a very small compact power supply which is why it is handy.
Below is a picture of my spare one. A friend who owns a surplus store gave it to me as it got dropped and smashed. I was hoping to find a junker somewhere and use it for the case but have not had any luck with that. I will probably eventually just get a plastic box and drop it in there.
(http://www.milspec.ca/board/img/P2055969.jpg)
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Yeah, I ageee the smaller HP Aligent supplies are good options, especially for the price compared to their larger siblings.
I have various power supplies, but I still would not mind a programmable lab supply like one of the Amrel units from years ago. However one of my concerns is getting a supply with a failed unobtanium part.
An example:
http://www.kerrywong.com/2015/05/06/amrel-pps-2322-programmable-power-supply-teardown/
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I have an Agilent 66309D, a E3615A and a 3644A in the shop. You can see the 66309D and the E3615A at the bottom of my rack. I will be swapping the E3615A for the 3644A at some point. All are programmable, mind you, not via numerical keypad, but twirling the knob doesn’t bother me. All 3 are nice power supplies. E3615As are reasonably priced on the surplus market.
(http://www.milspec.ca/board/img/P8055754.jpg)
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Ya' had to go there. :p I do not even have a home office anymore. I think about doing a radio room or area of sort, but then I think about how often I would actually use it.
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Think one or both of my active miniwhips might have been damaged in a recent thunderstorm. Need to check the antennas and power supplies further. Yay?
I have like 2-3 amplified antennas collecting dust in parts storage as possible replacements if needed, but I am debating about even bothering with them. I mostly use my 31' vertical for casual MW/HF listening anyway.
It is about time to take a closer look at the existing antenna farm, too. I would like to update feedlines, deploy more and better radials for my ground-mounted verticals, etc.
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I just finished relocating 800 km North of my previous QTH so my antenna farm and radio room will be in "rebuild" mode over the next few months and over the summer. All I currently have active is one mini-whip antenna hanging indoors in a patio door connected to my Icom. More to follow ...
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Hudson Bay area, perhaps?
I am dealing with a moderate noise issue apparently from a local temporary power drop to a couple of nearby houses under construction. Suppose I will ignore it for now, at least until the houses are finished. Afterwards if it still persists, then time to contact the power company.
Thankfully is a not powerful broadband RFI, and it seems mostly limited to around 7-9MHz, though that could just be my 31' antenna at play. I can null it even with just a passive YouLoop antenna, so I am thinking about deploying a small active loop antenna for the affected spectrum in the meantime. I have a modified MLA-30 that should suffice, if/when I get around to it.
I have considered a W6LVP or similar active loop.... or maybe building a rotatable HF delta loop, kind of like the models EAntenna offers, but more affordably with poles and wire instead of tubing. It would be a vertical delta loop at mid- to upper-HF, and conversely, a small receiving loop at low-HF and below. Anyway, just kicking around a few ideas for now.
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Hudson Bay area, perhaps?
Almost, Grid: FN08, Elevation: 275 Meters (902.23 Feet)
I temporarily put up my end-fed longwire last night connected to the ICOM IC-705. Propagation is poor this morning and the bands have been very quiet. Bonus, so far, no more urban / city RFI to deal with. WWVH on 10 MHz has been coming in strong most morning on the mini-whip and ICOM IC-R75.
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Congrats on the low RFI situation.
My local noise floor is surprisingly decent most of the time, especially for a neighborhood. Just happens every few years something seems to pop up. Thankfully the power company has been good to respond when it was their issue(s).
Picked up parts to build a basic freestanding inverted vertical delta loop. I am targeting about a 36' perimeter so it should resonate in the 11m band, assuming I ever bother using it for transmitting. Otherwise it still should be small enough to have some directivity as a receiving loop on lower HF bands, thus hopefully mitigating that annoying RFI until those nearby houses are completed and the temp power drop replaced with a permanent one.
Now to actually get around to building the antenna.... ;)
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Just got the RSPduo connected back up to the end-fed longwire. I am running at about -120 dBm for the noise floor. The antenna is currently not at optimum. 42 ft of wire about 8 ft or so off the ground terminated in a Palomar Engineers end-fed bullet transformer. At least I am on the air and can look forward to see how the pirates will perform.
(http://www.milspec.ca/board/img/2022-06-16_205440.png)
Update: 01:04 UTC 17 June 2022 - CHIL World Radio on 6925.0 kHz is making it up this way with a good signal. The noise floor on this portion of the band is at -110 dBm.
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Congrats on the low RFI situation.
Picked up parts to build a basic freestanding inverted vertical delta loop. I am targeting about a 36' perimeter so it should resonate in the 11m band, assuming I ever bother using it for transmitting. Otherwise it still should be small enough to have some directivity as a receiving loop on lower HF bands, thus hopefully mitigating that annoying RFI until those nearby houses are completed and the temp power drop replaced with a permanent one.
Now to actually get around to building the antenna.... ;)
Could be not so good, with the loop being a 'top hat' on the line acting as an antenna (in common mode or outside of the coax). So try to cut the loop in the exact middle, with the line in the middle plane, to make things as symetrical as possible. An ATU could help, otherwise use the high-Z antenna input.
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The basic design idea:
http://www.eantenna.es/?page_id=2571
I agree inverted delta loops ideally should be symmetrical with adequate common-mode mitigation when fed at the base. Otherwise the primary concern is the takeoff angle tends to go high if fed at the base, especially as frequency increases above resonance. I am targeting upper HF with the design, so conversely it should start resembling a small receiving loop as frequency drops to low HF and lower anyway.
BTW, the only place I might use it for transmitting would be 11m, though that would be secondary at best as I already have half-wave verticals for DX on that band.
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Still not built the vertical loop, or done much with radios for a few months now.
Hooked up the 31' vertical, built a recent SDRangel checkout, and turned on the Airspy HF+D while the hurricane has been moving through FL. Thankfully my area was largely spared.
Need to check on the antenna farm. Not from wind or anything, but more because it has been mostly out of use over the summer. Probably need to fix a few ground radials and similar maintenance.
Still thinking about deploying a small 11m beam like the Maco V-Quad. Some upper HF directivity would be nice for European DX and similar.
On a positive note, my lower HF noise condition is much improved. AFAICT, those two new nearby houses are complete, and the temporary power drop is not in use. The electric company still needs to do the permanent drops, but the other nearby residential drops in the neighborhood largely behave, so hopefully those will play nice as well.
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Glad to hear you dodged the IAN bullet, Rob. I used to live in Destin - I know the feeling.
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Thanks for the positive thoughts.
I dropped Elf36 a PM. He is in the Orlando area. Hoping he and his family are okay.
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Elf36 replied a few minutes ago. Thankfully he and his family are okay.
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I believe Outhouse Radio is out Florida way as well --- but don't quote me on that.
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Swapped around a couple of outside connections for testing. Could be both my active antennas are either cooked and/or have feedline problems. Need to break out a meter later to check them later. Fun stuff.
Hopefully my 18' 10m/11m vertical should be okay other maybe fixing a couple of ground radials radials..
Kind of curious to see if my 148' LoG is still okay.
FWIW, I have been relying upon my 31' vertical for basically all HF and lower bands for quite awhile now.
I probably should be looking at replacing multiple feed lines, along with eventually installing a remote antenna switch I have collecting dust on a shelf.
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Both active antennas appear cooked. Ground radials on the 18' vertical cut. A couple of cut feedlines. Pulled up a few runs of old RG-6 coax while taking a look.
Hoping to check the 148' LoG and fix the 18' vertical ground radials over the weekend.
Thinking I might still have a spare active antenna board of the same model as those previously deployed. Perhaps a quick fix for one of them.
I am pretty sure there is a generic eBay clone of an active antenna in my parts. The enclosure is probably sealed knowing my luck, thus no idea on what design it actually is. I suppose "whatever" assuming it works.
Also I do know there is a MLA-30 in parts storage that I modified but never actually deployed. Not a great antenna, but I might toss it up in the meantime anyway.
Otherwise, it could be time to seriously consider revamping part of the antenna farm. Near the top of the list is improving feedlines on my receiving antennas. Maybe direct-bury RG-11.
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Rob, you sure have had a run of bad luck with your antennae farm.
Have a look here for another "mini-whip" kit.
VE3FEX amplified antenna kit:
http://www.ontars.com/cgi-bin/classifieds/classifieds.cgi?session_key=&search_and_display_db_button=on&db_id=4337&query=retrieval (http://www.ontars.com/cgi-bin/classifieds/classifieds.cgi?session_key=&search_and_display_db_button=on&db_id=4337&query=retrieval)
and
https://ontars.com/whip_kit/index.html (https://ontars.com/whip_kit/index.html)
I wish I would have known about this kit before importing "clones" from overseas. It appears to be well built. There is also a review by VE3CV on the same page. It might be something worth considering.
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I will take a look. Thanks.
Appears my 148' LoG is out, too. At least I assume it was the right feedline I reconnected in the dark outside. :D
I am down to my 31' vertical tonight. S5 noise floor with higher static crashes around ~7MHz, too. Sigh.
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Dunno if I mentioned this before, but a loop of wire tacked under the eaves, fed by coax, can make for a fine multiband (with transmatch) rx antenna, with a few caveats. First is in-house noise sources picked up by said loop, but this is often under the control of the listener such as turning off noisemakers. These antennae are very hardy as your house will have to be destroyed to take it down unintentionally, more or less. A transmatch (aka antenna tuner) will help wring most rf from this or any other antenna. Might not want to use it as a hf tx ant but that has and does take place.
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Gutters as well, assuming they are bonded decently and not grounded.
As to my ongoing antenna farm adventures, I might be moving some antennas, including my 31' vertical.
Last night I deployed a temporary ~12.5' vertical wire on a fiberglass rod and tripod. Used a 9:1 receiving balun, which was far from optimal, but it was small and in a spare parts bin. Only a single on-ground radial. An 1:1 choke is back near the house. Even factoring the subpar design and associated losses, RFI on HF seems to be comparatively quiet where I deployed it.
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Beats the ice hanging off my antennae. Freezing rain for the past 24 hours. I have a 50 ft long guy wire off of one of the legs of the T2FD. It's sagging ... but so far hanging on.
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I recently put up a 10-11 Meter Band 1/2 wave Vertical (non ground wave) works better on MW then 10-11. Very disappointed with it tbh.
Maybe not high enough at around 20' high though
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Winter weather and Florida do not mix well. IIRC, years ago like 1" of snow shutdown much of Tampa.
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Zero33, curious, homebrew or commercial? Type of coax used?
My "18' end-fed vertical" is a Shakespeare 318-GBT. It is mounted above 6" above ground, along with 8x 9' on-ground radials*. Works great for DX. Admittedly, I do not care much about local comms. Anyway, much below 20m it requires an antenna tuner or a preamp for realistic reception. On MW the resistance is probably low enough to about look like a short to a receiver.
*Regarding ground radials, Kirchhoff's current law still applies to end-fed antennas, so in reality end-feds are more like extremely offset-fed dipoles. There is return coupling somewhere. Without radials the return coupling can be nearby objects, the mast if metallic, and/or oftentimes common-mode on the feedline. YMMV.
Anyway, if your ~18' end-fed vertical is working nicely on MW, it could be more like your feedline acting as the MW antenna due to common mode or similar. Experimenting with RF choking along the feedline might help.
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Its a commercially made CB-10-11 meter antenna from a local Aus supplier, I"m using RG-213 and through to my IC-7300 also have an unlocked Lincoln II + for 11 meters.
I am in the process of making a home made centre fed dipole hoping for better results.
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My Youloop has been having issues. Popped it open, and looked like a broken transformer. Yeah, like I am repairing that *tiny* winding. I do good to barely solder through-hole parts anymore. Not worth trying to source a replacement from Coilcraft or wherever, either.
So I popped the transformer off the PCB. Wound an 1:1 on a mix 73 binocular core like often used use on homebrew mobius small loops, and mounted it outside the enclosure. "Whatever" to the aesthetics.
Waiting on the glue holding the ferrite to dry, then finish a couple of connections and (re-)pot the boards with hot glue. Suppose I need to go find my NanoVNA, too.
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Why not just contact AirSpy and see what they have to say. You never know. You might be able to get a replacement.
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I potted it once upon a time, so I probably damaged it. ;)
The enclosures are back together. Replaced the also damaged RG-402 loop coax with RG-6. A quick VNA sweep looks approximately like my previous Youloop measurement. I think the resonant frequency shifted somewhat, but again, a whatever given it is not a low SWR antenna anywhere in the HF and lower bands. I did not check VHF.
It is hanging in a window in one of the nosiest RFI locations inside the house. An elevated noise floor as expected, but it is generally working. I have already skimmed signals on 80m SSB, 11m AM locals, and a local MW BCB station.
I have interesting somewhat intermittent RFI on ~273KHz and upward harmonics. It is present on my 31' vertical as well, but it is 10s of dBs down there. Given the frequency I am inclined to think a switching DC voltage regulator somewhere in the house. Fun. Suppose I should now find my TinySA analyzer, but maybe later this weekend.
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Longwave reception tonight. Have a carrier on 153KHz, and actual modulation on 171KHz.
Noted around 0700z:
153KHz - carrier in waterfall | possibly Radio Antena Satelor
171KHz - Medi 1 at SINPO 15242 trending 15241 with moderate to frequent static crashing from regional storms
I might do better with Medi 1 assuming I understood the language. Anyway.
Interesting part (for me) is using my 31' vertical with 4:1 unun and moderate ground radial field. I usually have to use my 148' loop-on-ground for longwave BCB listening, and it is out of commission pending repair or replacement.
BTW, I pushed my luck with the vertical further down the spectrum. 24Khz NAA, 25.2Khz NML, and 40.7KHz NAU are present tonight. Not difficult catches, but nonetheless there.
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Tossed the factory feedpoint PCB and enclosure. Salvaged the connectors, which I mounted in a cheap plastic enclosure. Changed the wiring to (potentially) improve isolation by removing the homebrew design's ground from the loop shield to feedline ground that AFAICT basically turns the balun into something more like an unun. YMMV.
Regional 80/75m activity looks decent this morning considering the loop is in roughly the same indoor RFI noisy location as last night, along with a LCD TV powered on about 10'-12' away.
(https://i.imgur.com/JBM0GrA.jpg)
Likewise decent noise floor on the 49m band.
(https://i.imgur.com/jVlpm5g.jpg)
Next up the 40m/41m bands.
(https://i.imgur.com/xgSlzOF.jpg)
20m SSB activity is starting to trickle into the waterfall.
(https://i.imgur.com/qL3dff3.jpg)
Several CW ops working the 15m band.
(https://i.imgur.com/Dws68Yz.jpg)
Faint activity on 27025am including an op in Ireland working DX into NA. Not too bad for an indoor loop hanging in a window.
(https://i.imgur.com/tc0U2gM.jpg)
Some CW traffic on the 10m band.
(https://i.imgur.com/mBTD710.jpg)
VHF NOAA weather.
(https://i.imgur.com/olIaqaX.jpg)
Local daytime MW is not worth screenshots. One or two locals, plus a few relatively faint regional stations. At least it is working for MW.
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That is actually pretty good VLF / LF reception. I currently have one of my mini-whips in the window but I think I might replace it with my YouLoop to test it out. I still have not re-installed the Wellbrook loop after the move. Just recently swapped my end-fed longwire for my T2FD and finally got the RG-58 replaced with RG-213 yesterday. Hope to at least get the Wellbrook up before winter sets in.
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Congrats on getting the T2FD back in service. :)
Poking around "new" ideas, modelling for the SULA terminated loop looks interesting.
https://swling.com/blog/2022/08/introducing-the-amazing-sula-an-affordable-unidirectional-dx-grade-loop-antenna-that-you-can-build/
As modeled it has a wide frontal horizontal lobe pattern, though with a ~20dB F/B ratio for much of HF and a considerable back null from MW to 40m. "Gain" is well into negative dBs, but to be fair, it is not much different than many beverage or loop-on-ground designs. A preamp is simple enough to add if needed.
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Temps are cooling, so it is about time to actually take a serious look at the antenna farm.
Just ordered an 1000' spool of Belden PPC RG-11 direct bury coax. I probably will have to enlist some help, but I intend to hopefully bury most of my feedlines.
https://www.ppc-online.com/hubfs/2057289/Downloadable_docs/Spec_sheets/Coax_Cable/Series_11_Underground/P11ET77EFRF.pdf
It has a CCS center conductor, which could be a low frequency concern due to skin effect, but the current cheap RG-6 deployed on most of my antennas suffices okay for my receiving purposes down to longwave. I probably would have went with a solid copper center if transmitting on 160m or lower, but I am not, so whatever.
I am thinking about moving the 31' vertical from ground mounted to ~10'-20' elevated. Probably just a couple of elevated ground radials, or maybe even only one for a little directivity potential, since it is a receiving antenna.
https://www.qsl.net/kk4obi/Center-fed%20L-dipoles%20Vertical.html
I should just outright replace the old 148' loop-on-ground. I might move it as well, as the existing far side of the square loop parallels to close power lines.
The two failed active miniwhips are likely to be replaced with a generic eBay active miniwhip and a MLA-30+ amplified loop. Yeah, neither are great antennas, but I already have them.
I do not have much interest above HF, but I do have a cheap little discone collecting dust. Instead of dealing with yet another mast, I am considering crimping and/or soldering a loop connector to the vertical tip and hanging it via rope line from a tree branch. It is omni anyway, so it is not likely a little movement is going to affect it too much.
I might get all that done in a few weeks.... or hopefully at least by next spring. lol
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Somewhere along the way I hope to have some type of small radio area. For quite awhile now I have been mostly using a notebook+SDR in the den and a Kenwood R-2000 on the bedroom nightstand. It could be much worse, but it might motivate me to obtain an amateur license if I had a dedicated radio space, if I have a dedicated radio space.
BTW, the R-2000 is still using that temporary 13' fiberglass fishing pole vertical mounted on a tripod I slapped together awhile back. Another it could be worse situation, as at least it is outdoor antenna.
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Airspy HF+D using the bundled USB cable having two ferrites along with a common USB extension cable.
(https://i.imgur.com/CpTJHfZ.jpg)
Airspy HF+D using the bundled USB cable having two ferrites along with a (supposedly?) quality USB extension cable wrapped 10 turns around a Fair-Rite 0431177081 mix 31 snap choke.
(https://i.imgur.com/Si501od.jpg)
Both using my 31' vertical over a radial field. 4:1 unun at antenna feedpoint. KD9SV CMC inline choke near house. Multiple coax passes through a HF-rated (mix 31, 43, whatever) at the SDR input.
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Second config, but on notebook battery power.
(https://i.imgur.com/sMrZFHr.jpg)
I am thinking about adding enhanced EMI/RFI filtering and maybe even metal encasing a compatible notebook power supply.
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Try to wire an EMI / RFI filter backwards.
Have a look at PA0NHC Main Index web page. There is some good information there like "De-noising of Switched Mode Power Supplies". This is where I first got the idea of wiring the filter backwards. https://www.pa0nhc.nl/ (https://www.pa0nhc.nl/)
Don't forget about your peripheral devices; I.E. mouse, keyboard, printer cable, Ethernet cable etc ... They are all sources of "noise".
Some pretty good references can also be found at the K9YC site like the "A Ham's Guide to RFI, Ferrites, Baluns, and Audio Interfacing" pdf: http://www.audiosystemsgroup.com/K9YC/K9YC-old.htm (http://www.audiosystemsgroup.com/K9YC/K9YC-old.htm)
EMI / RFI is a never ending battle.
P.S. Some interesting DYI construction ideas can be found here: https://www.kf7p.com/KF7P/RF_chokes.html (https://www.kf7p.com/KF7P/RF_chokes.html)
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It is the notebook power supply itself, and most likely on the DC output side. On the AC input side is an APC Line-R.
I was more or less just pointing out the bundled USB cable with the Airspy HF+D might not have enough choking, especially at lower frequencies, for some systems despite it already having a couple of ferrites. ;)
If I ever bother with EMI/RFI filter mods to the particular supply, initially it probably will be a few caps and a inductor on the DC output side. The next step would be additional AC input filtering and mounting the whole thing in a metal enclosure if actually needed.
For an example:
http://ka7oei.blogspot.com/2014/08/completely-containing-switching-power.html
BTW, that is my quiet 150w HP notebook supply. The noise falls off relatively fast above longwave. Conversely I have another later revision of the model that might as well be a wideband transmitter. o.0
About the ferrite, the Fair-Rite 0431177081 is a rather large mix 31 snap choke capable of winding numerous USB cable passes. I could have done more than 10 passes, but I would have needed an even longer USB extension cable for my current setup. Arrow Electronics currently has the model for around $10 plus shipping, or free shipping with a free perks membership and an $100+ order.
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I have an IBM Thinkpad which is just as brutal of a hash generator!
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Belden RG-11 and connectors arrived. Still waiting on a new F connector compression tool, as my existing one is limited to F connectors for RG-6/59.
I suppose first on the priority list should my usual "go to" HF antenna these days. Moving the 31' vertical to an elevated install should not be a huge issue at least logistically. It works fine ground mounted right now, but I would like to get rid of the radial field in the backyard.
I already have a couple of cemented 4x4 posts, four cemented guy stays, and brackets to install the mast from a previous 11m antenna project. I should have room for at least a couple of opposing elevated ground radials, assuming I do not try a singe radial for a little potential directivity.
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Might be a decent radio day here. Been listening to various regional 2m ops via my 31' vertical. o.0 Yeah I know, but it is the only working feedline routed to my Airspy HF+D right now.
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Had help available today. :)
Nearly all of the old bulk RG-6 coax feedlines and on-ground radials are out of the yard. The 148' LoG built using RG-6 is still in the woods, so that might be a task for another day.
The 31' vertical is down and being prepped to be mast mounted. 4:1 unun, various clamps, mast guys, and two 31' radials are connected. The vertical antenna might get deployed today, though the two radials might just run down to the ground for tonight. I really could use a couple of eye bolts for the far ends of the radials, but I am not finding any large enough in the parts bins.
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We got the 31' vertical on about 21' of mast and the guys done.
Dropped a temp feedline to the house. Turned on the SDR, and normally strong signals are barely above the noise floor. Troubleshoot it tomorrow I guess.
So I am down to temporary vertical on a tripod in the yard for now.
Did a NanoVNA sweep at the base of the mast. The problem is somewhere up the mast. Either the feedline, which I checked earlier, or perhaps the unun that was previously working.
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The 31' vertical is back in business. It is dropped down to just ~10' of mast, that way the feedpoint can be serviced without having to take the mast and guys down.
The 4:1 unun probably has a broken connector or wire inside. Something to perhaps check later. I had an 1:1 in the parts bins, so I am using it for now.
Next up for twice the fun, despite earlier testing okay, the RG-11 appears to have a bad connector or similar. Figures. My coax stripper does not do RG-11, so just guesstimated it by hand with wire cutters. I have a stripper for RG-11 on order. I replaced the coax temporarily with a run of RG-6 I had already.
I removed the two 31' horizontal radials to simplify things. I just connected the balun ground to the mast and guys lines. Whatever, as it is just a receiving antenna anyway.
Did a NanoVNA sweep. SWR dips right above the 40m band and the third harmonic as expected. The cheap RG-6 has enough loss to somewhat smooth out the impedance from MW through 30MHz anyway. ;)
Net result? I doubt performance is much different than when ground mounted, but at least it gets the numerous 31' on-ground radials out of the yard.
I would have looked at the active antennas, but oddly enough, it seems I am out of RG-6 coax. ?!
Quickly skimmed 10m. A net in California, an op in Brazil working DX, and a few other signals. No preamp. Not bad IMO.
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Rob, if the guy lines are metal / conductive, you could do what we do on AM towers and that is to put insulators in-line with the guy wires. This should give you working radials. If you look closely at guy lines on AM towers somewhere along the way you will see an insulator. There is a formula for it but in a nut shell, less than a 1/4 wavelength of the operating frequency so that the guys do not resonate. In your case you want it to resonate so, insulators at both ends and bond them together at the top. A little hard to explain but I think you get the idea.
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Sure enough. Before I have had a upper-HF vertical antenna using the guy lines with insulators as radials.
No insulators on the guys for this deployment. Using 14ga galvanized electric fence wire as guy wires since they are only lightly loaded with a 10' mast. The vertical lobe at low angles might not be ideal if modeled, but it is working okay enough (for now) for casual listening.
Better than the temporary 12' vertical on a tripod I am still using for the nightstand receiver. I am thinking possibly using an active miniwhip there.
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I'm using one of my mini-whips on the nightstand receiver, the ICOM IC-R75, and I am not very pleased with it, mind you, it's inside hanging from the curtain rod and well camouflaged by the curtains. I had limited success with 2nd mini-whip which was externally mounted on the communication mast at my prior location. I have yet to install one outside at my new location to see how it performs. It was -11 F this morning so no thank you ... not until it get warmer out.
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Do you RF ground your indoor miniwhip? A ground wire even to an outlet ground might help. I have done it before in a pinch for a temporary setup. Huge YMMV depending upon electrical system RFI.
Could you hang it from an eve or gutter? Snake some RG-179 or RG-316 through the window. I have done that with the coax under the closed window in a piece of un-shrunk heatshrink tubing to get a feedline outside.
I often use those inexpensive eBay 75-ohm "flat" coax jumpers under windows. Most are not really flat, but more like probably RG-179 or similar inside the casing. They are typically less than 1' long, so losses are no big deal at HF and lower.
Since the 31' vertical feedpoint is readily accessible, I intend to replace the 1:1 balun with another unun to flatten the multi-band impedance curve at the feedpoint at little. Balancing losses at the feedpoint versus losses in the feedline. Yeah, I know is not a big deal for receiving, but I do not mind experimenting a little with the deployment during cooler weather.
I was considering another basic 4:1 unun, but I kept thinking about what G8JNJ did after analyzing the Comet CHA-250B match.
https://www.g8jnj.net/cometcha250b.htm
I considered building one, but then I stumbled across a similar dual-ferrite unun on eBay. :)
https://www.ebay.com/itm/303018040561
It is a little different design, but the same idea. I am not entirely sure how it will fare under 80m, but "whatever" as long as S is decently over N considering the usual noise levels down there anyway. Either way it probably will perform no worse than a simple 4:1 unun, so again, a "whatever" for my purposes. Something different to try I suppose.
At some point I might try the even simplier G8JNJ approach to multiband vertical matching using a bifilar winding on an iron powder core. It is further down the previously linked page. I still have an S9v18 vertical in storage.
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The mini-whip is just floating with about 20 or so feet of coax and a choke at the radio end (between the bias-t and the receiver). I can try coupling to the AC ground and see what happens. Getting through the patio door is a challenge, specially when the temperatures are -10 or lower at this time of year. I should have got some of those flat ribbon pass-through the last time I was at the store. If anything, it would have been worth the test. Even when I had this mini-whip hanging outside it performed just ok, not that great. I'm actually surprised that it picks up as much as it does. I might hang the YouLoop in the patio door instead and see what happens.
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Based upon my experience, you will likely do better with the Youloop and a preamp (if needed). At least it is a relatively balanced antenna, versus a miniwhip using the coax as a RF ground, so hopefully better SNR even if lower S levels.
I used to use a Youloop in a window as a backup indoor antenna during storms. Extra gain when needed was usually via a MFJ-1020B or a cheap eBay "+20dB" wideband preamp.
Estimated regional MUF is ~14MHz at 0958z. Numerous stations on the 19m band. Like 4-5 stations on the 16m band. Not too bad.
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Not BCB, but MW related. Winter season activity has arrived on 160m. Multiple frequencies being worked with CW, digital, and SSB at 0252z.
Moving much further down the spectrum, I am listening to Medi 1 on longwave at the moment.
Now on to Radio Algerie International on longwave.
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I can barely solder anymore, but anyway, the eBay dual-ferrite unun is in an enclosure.
(https://i.imgur.com/QeRBHZ9.jpg)
Yeah, the SO-239 mounting screws are long. They are what I had available. I have a dremel, but doubt I will bother.
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The dual-ferrite unun installed on the 31' vertical antenna elevated on a 10' mast, grounded back to the mast and metal guy lines. No VNA compensation for the feedline, so it is pretty much what the receiver is seeing. Still running RG-6 for now. Hoping to get my RG-11 deployed in the near future.
(https://i.imgur.com/HtTPtgp.jpg)
As to the nightstand receiver, I recently swapped the temporary 12' vertical on the tripod to an eBay made-in-China active miniwhip on a piece of PVC pipe stuck into the tripod. RF ground is the feedline back to an 1:1 choke near the house. Not a great improvement, and not like I expected much. There is some mediumwave improvement.
I stiil have my masts for active antennas or whatever. I even have a few antenna choices available. I just need to get them deployed.
Speaking of active antennas, I had to fix three of my bias tee injectors, including completely replacing the board in one. IIRC, I kept my old active antennas to check them further, so there might be a slight chance they were actually okay.
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Oh my, that looks like a very noisy antenna based on the SDR screen, or maybe it is just the way it is displayed.
Here is my Barker & Williamson T2FD antenna with a 30 dB NooElect Flamingo AM Broadcast Band Notch Filter installed at the SDR's input. As expected, one station every 10 kHz. Now that I am 400 miles North of all of those 50 kW Toronto broadcast band transmitters that used to be in my back yard and overloading the front end of my receiver I probably no longer need the notch filter.
(http://www.milspec.ca/board/img/2022-12-22_222143.png)
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I had the waterfall rather squished. A little better now? ;)
Quick look at the mediumwave band. External inline attenuator is set to no attenuation.
(https://i.imgur.com/AUTn4Ay.png)
Alternatively using SDRSharp under Wine.
(https://i.imgur.com/dnT9tDr.png)
Skimmed longwave BCB. Just Medi 1 right now, but that is not bad IMO considering current regional thunderstorms.
https://www.hfunderground.com/board/index.php/topic,107149.0.html
Some NDBs between longwave BCB and mediumwave BCB.
A few of the more powerful signals moving further down the spectrum....
60KHz - WWV - S6 - 40dB SNR
40.75KHz - NAU Puerto Rico - S6 - 30dB SNR
25.2KHz - NML North Dakota - S4 - 24dB SNR
24KHz - NAA Maine - S5+ - 25dB SNR
8KHz - ?? - S5 - 32dB SBR
Low frequency seems to be working okay. :)
Both of my decent PA0NHC active miniwhips work! Glad I kept them to check out. The prob was damaged bias tees.
I intend to put them right back on their existing masts along with new feedlines.
Replaced the temporary active miniwhip with a temporary active loop. Copper wire inside a hulahoop feeding a MLA-30 preamp modified with a F connector, all wire tied to a PVC pipe stuck into a tripod. I pointed it vaugely NNW/SSE to favor NA for now. I am not sure SNR is improved much, but gain is improved on at least a couple of bands where the miniwhip was quite low.
The 31' vertical with the new unun is working okay for upper-HF as well. Listening to the European 11m SSB traffic right now.
Been raining otherwise I might have considered fixing the small on-ground radial field on my 18' end-fed vertical this morning. Maybe later or tomorrow if it dries up.... or the ground freezes, which is a possibility this weekend in Florida. o.0
Lowered voltage at the bias tee I was using to feed the MLA-30 preamp down to 4.5v last night. Add some voltage drop due to 75' of RG-6 feedline. Gain barely dropped at lower-HF bands and MW, while SNR likely improved. I still need to check voltage versus gain on upper-HF bands.
Positive supply voltage for the TL592B differential amp is listed at 3v to 8v. That tracks with my results. Gain at 3v (minus line loss) dropped considerably. The preamp at 1.5v dropped out.
12vDC as supplied by the stock USB->12vDC boost regulator in the bundled bias tee is likely overdriving the amp IC and potentially affecting SNR. YMMV, of course.
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Those screen shots definitely look better. I cannot drop down much further with the B&W T2FD antenna. It has a pretty sharp roll-off below 1.8 MHz. That antenna is not designed for use that low. This is where I used to switch to the vertical, the end-fed or the loop antenna.
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My temporary loop is nearly a short on MW and lower now. I swapped the MLA-30 preamp with an 1:1 balun.
Turned on the Kenwood R-2000 to be greated to horrid broadband RFI. o.O Turning the loop did not help much. There is not much use having a noisy preamp further amplifying RFI noise.
The reciever noise blanker helps, plus I put a MFJ 1030B in line for preselection and a comparatively better preamp. Forget weak signal work, but least I am back in business for casual listening in the bedroom. I did not even bother to check the SDR and 31' vertical this afternoon, though I seriously doubt the situaton is any better with them.
I am hoping the RFI is temporary. The same or very similar RFI sound has happened in the past and went away after a day or two. If not, I get to break out a portable and go searching. Been there, done that, and had to file reports with the power company. Fun stuff.
Found a few degrees of rotation with lower RFI noise floor using a portable tuned to longwave. I turned the loop edgewise perpendicular to the portable. MW seems better. Not enough directivity on HF to matter much. Anyway.
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Significantly elevated noise on 40m today. Sure, I can knock it down with noise blanking and some attentuation, but it is still quite irksome.
HF readings with my TinySA look rather flat near the house. I probably should make a loopstick or some other low frequency antenna for it.
It was a broken pole insulator several years ago, but that was right in front of the house. It was a rather quick fix once the tech came out.
A few years ago it was something neither the power company or I could really pinpoint, though the tech did do a little general pole maintenance in the area while hunting. Thankfully it just went away a few days later.
I used to occasionally notice RFI from something that sounded like maybe a plasma television or similar, but it was low-level enough and rare enough to be more of a mild annoyance than an issue.
Tracked down a small part of the immediately local RFI to tool battery chargers in the garage. Unplugged them for now.
The Samsung washer and dryer control boards are not exactly RF quite, either, but they do not seem to be affecting my SDR in the den and 31' vertical in the backyard.
Guess I get to go for a drive around the neighborhood one day.
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Rob,
I built a direction finding (DF) loop antenna some time ago based on the design found at QRM Guru (https://qrm.guru/) and it works very well.
Look under Direction Finding (DF) Loop Antenna Kit and follow the link to the video How to locate the noise source: building a DF Loop.
This is a picture of my finished product. I added a small wooden dowel to retain the form and also provide a handle to hold the loop antenna with while sweeping for signals.
(http://www.milspec.ca/board/img/PC306547.JPG)
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A shielded coaxial loop. That is basically how I build my loop-on-ground antennas, though naturally much larger and with the loop "shield" connected to a ground rod.
I could use my existing hula loop as a portable easily enough, though that might look a little odd to the neighbors. ;)
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Don't the neighbours already think things are odd at your place already anyways? LOL
I would have loved to have known what some of my neighbours back at my former location thought of my antenna farm sprouting out from every corner of the house!
I got the Wellbrook loop antenna up again this afternoon. All that is left to do on this antenna now is to run the control cable to the rotator. For now it is in a fixed beam pointing to central USA which also gets me somewhat in the middle of London / Africa on the back side.
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Congrats on getting the loop back up. :) Did it actually get above freezing for awhile today?
Thankfully my neighbors do not say much of anything about my antennas.
I got one PA0NHC miniwhip redeployed today. Went right back to the mast where I removed it awhile back.
I ran the "proper" RF ground wire from the miniwhip PCB to the mast this time. Previously I just used clamps around F barrel connectors along the coax and mast for RF grounding. Anyway.
Feedline is like ~120' of Belden PPC RG-11 to the backyard. Still needs buried, but that is a job for another day.
Four snap chokes at the base of the mast. TDK whatever mix since I already had them in parts box. The chokes are better at VHF+, but I remember the specs still showing some RF choking at HF. I have a bunch of them available.
The bias tee has an integrated choke. I have a KD9SV SV-CMC choke before the Kenwood-2000 as well.
The very bottom of mediumwave and down into longwave has that annoying area RFI that recently popped up, but mid-MW to 10m has a low enough noise floor and decent enough SNR for casual listening in the bedroom. I left my MFJ-1020B inline for added gain and preselection, though it might be removed if not really needed.
Next up might be the 18' "end-fed" vertical. It just needs a few ground radials redeployed and the feedline rerouted.
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Yup, it has been above freezing for the past several days, raining and 46 deg F today. It should hover around the freezing mark for the next week.
I am very pleased with having the Wellbrook loop back up. It is 13 db quieter than the T2FD and makes a world of difference. I can pick-up signals on the Wellbrook that the T2FD doesn’t even register.
T2FD:
(http://www.milspec.ca/board/img/2022-12-30_212724.png)
Wellbrook loop:
(http://www.milspec.ca/board/img/2022-12-30_212812.png)
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Nice SNR bump on the loop. 8)
BTW, I am having to copy-and-paste your image URLs. Is your personal site perhaps blocking image hotlinking?
I am thinking about having my Kenwood R-2000 recapped and aligned; both of which are likely still factory. Likewise I could imagine the front-end Q1 amp and Q2 follower have taken considerable abuse after several years of Florida thunderstorms. I do not feel like bothering with it myself, plus I have other desktop HF receivers, but it is my favorite.
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No blocking in effect, it is your browser setting. Images are hosted over http and the HFU is over https. This is called "mixed mode". There will be a setting somewhere in the browser to allow "mixed mode" browsing. I am willing to bet that you are using a Chrome based browser. Google, the self proclaimed "Internet police", at some point elected to disallow mixed mode browsing therefore by default, all Chrome based browsers have that function disabled.
It's a scam if you ask me. There is no need for https (encrypted traffic between the server and browser) unless processing / accessing sensitive data such as on-line banking or on-line shopping yet Google has forced everyone to adopt https so that they can get that pretty little "green shield" next to the URL bar that gives people that false fuzzy safe feeling that the content they are viewing is "safe". That couldn't be any further than the truth. But hey, certificate authority companies love it. They are raking in the cash by issuing people / sites certificates. For me, my hosting provider wants $100s of dollars to install a certificate. They won't even allow me as the site owners to install my own like Let's Encrypt . BS that is. Some day I have to find another provider.
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Makes sense. I did not look closely at the URLs, as like you noted, most larger sites use SSL these days.
I have added your domain to my own local treat as secure list.
chrome://flags/#unsafely-treat-insecure-origin-as-secure
BTW, I am using Chrome Canary on this tablet at the moment, but I tend to use my own optimized dev releases of Chromium on Linux, plus I do cross builds for Windows. I apply higher SIMD baselines, opt level tweaks, various additional LLVM passes, PolIy loop optimizations, etc. I have been building Chromium for years, even well before my GitHub repo releases.
https://github.com/RobRich999/Chromium_Clang
https://chromium.woolyss.com/
As I suspected, sensitivity is way down on the Kenwood R-2000 on a few HF bands. Suspect a failing cap or few, plus maybe the front-end amp and/or follower.
Tested against my R-600, which I rarely use, so naturally it is now drifting a little too much for my liking. Warm up helps, but that is annoying. Probably needs recapped as well, though I probably will check the usual R-600 suspect of cracked solder joints first.
So, want to figure out how to fit a Yaesu FRG-7 on a nightstand? lol Might have to toss a portable on there for awhile.
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LOL, that is why I have the ICOM IC-R75 on the nightstand. The clock / timer function in that receiver is perfect for me. I have it set to 1 hour and the radio turns off automatically.
I see you have been busy with Chromium_Clang. I personally despise Chrome and most derivatives. The only version I occasionally touch when I have issues with my old locked down version of Firefox ESR is a portable version of Iron Browser. The key being "portable", no traces of Chrome junk left behind.
Now, back to scanning the house for sources of EMI / RFI. I found an unused telephone jack at the service entrance yesterday that has a buzz to it so it has my curiosity peaked. I am using an ultrasonic probe to look for leakage.
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Actually, one of the best MW antennas that I remember making was to shunt-feed the 50ft tower that I had at the time. In the middle of the day, the NYC Big-3, (AM660, 770, and 880.), all came in at S9 from 300 miles away. Extremely low noise, being a couple hundred feet from the nearest powerlines. Originally, I did that to get on 160M, 75M, and 40M. On TX, a manual MFJ-941D tuner tuned all that in, but my GND losses were bad for transmit. However, on RX´ing, it was quite good. https://www.qsl.net/w9rb/webdoc9.htm
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My 148' LoG was a decent MW antenna. Still the isual nighttime issues with an omnidirectional on MW, though phasing against one of verticals could help.
Tossed a Tecsun PL-330 on the nighstand last night. Reception works okay for the particular purpose, and I used a portables on a nighstand with a grasswire antenna for quite awhile years ago. Just annoying to deal with small buttons.
Just noticed my -20dB variable attenuator was fully engaged, thus some of the low signal reports in my shortwave loggings this morning. o.0 Oh well.
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Anyone want to take a guess on the type of RFI? It reminds me of a switching power supply due to the relatively even spacing.
I have yet to locate the source, but it is immediately nearby going by the AM radio in the car. I will try to snag a recording later.
(https://i.imgur.com/qUgbFnM.png)
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Still not exactly where I would like it, but the RFI looks better.... for now? My LG dishwasher has a "night dry" feature that apparently keeps the electronics active and periodically runs a ventilation fan after washing. Stopped the dishwasher, and the noise floor dropped dramatically. A little attenuation or even baseband noise blanking in SDR# knocks down much what is left.
Noise is still a little elevated around 3-5MHz, but adding some attenuation around there is nothing really new here. I need to get a loop-on-ground redeployed.
Anyway, hopefully it is resolved or at least decreased for awhile.
(https://i.imgur.com/rCxm1dZ.png)
(https://i.imgur.com/N3VAP7S.png)
(https://i.imgur.com/8UDZSv1.png)
Around S2-S4 on 40m and S3-S4 on 80m at 1540z. I am on the 31' vertical at the moment, plus that is with no attenuation, so that is not too bad IMO. Well under S1 on 10m and floating around S1 on 2m during a quick skim. I will take it compared to yesterday. ;)
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The dishwasher --- LOL. Just can't elude the modern day EMI/RFI emitters.
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The dishwasher --- LOL. Just can't elude the modern day EMI/RFI emitters.
We had to replace ours a year ago, and I got a GE with a mechanical rotary knob (just like our old one) rather than an electronic control. No RFI, and I am extremely dubious of mixing electronics with hot steamy water. I know too many people who have had their fancy dishwashers die after just a few years.
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I am thinking about moving the 31' vertical back to a ground-level mount over a moderate radial field.
That would free up the existing mast. Maybe add another 10.5' section, and finally deploy the delta loop design I mentioned months ago. It should work decently at mid-HF, along with becoming more like a magnetic loop as frequency decreases. I could use a preamp to deal with the wideband matching if needed.
I would like to get another LoG deployed. I have been saying that for what, a couple of years now? o.0 Oh well, it is just a hobby.
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The dishwasher --- LOL. Just can't elude the modern day EMI/RFI emitters.
In my summer house in the evening there was a huge broadband noise on HF. I was furious until I accidentally discovered that it was a Chinese LED bulb screwed into the kitchen on the lower floor.
My cousin wanted to do the right thing, but he's not a radio amateur .
Also check the nearby switched on chargers - they can even give the S2 the noise visible on the waterfall. I am trying to replace them with a version built on a traditional transformer.
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Finally got the 18' "end-fed" vertical back online. :) The antenna system including its old Belden RG-8 feedline checks okay via the NanoVNA.
https://www.hfunderground.com/board/index.php/topic,115496.0.html
That particular RG-8 coax drop has been through multiple antennas and locations over probably 30 or more years now. I did get around to changing connectors a few years ago.
The eight ~9' on-ground radials are now copper instead of CCA wire. Lowes has 500' rolls of 20-gauge, high-tensile solid copper RF pet fence wire for around $30.
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The 18' end-fed vertical is working decently enough IMHO. I have already worked contacts in NA and SA.
https://www.hfunderground.com/board/index.php/topic,115636.0.html
https://www.hfunderground.com/board/index.php/topic,115688.0.html
I have been thinking about deploying an 18' monopole vertical with a YCCC feedpoint preamp for LW+MW. IOW, I have a S9v18 vertical collecting dust.
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The 18' end-fed vertical is working decently enough IMHO. I have already worked contacts in NA and SA.
https://www.hfunderground.com/board/index.php/topic,115636.0.html
https://www.hfunderground.com/board/index.php/topic,115688.0.html
I have been thinking about deploying an 18' monopole vertical with a YCCC feedpoint preamp for LW+MW. IOW, I have a S9v18 vertical collecting dust.
What is the frequency cover range on this antenna in reception?
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If talking about the 18' end-fed 11m vertical, it is an old Shakespeare 318-GBT. 26-30MHz, though the workable SWR curve of mine is somewhat narrower due having a radial field under it.
If talking about the S9v18, it is just an 18' wire inside extending fiberglass tubing. Frequency range would be largely based upon how it is fed. I mentioned a YCCC preamp, which is essentially unity gain. The YCCC is desgined to establish a ~75-ohm connection bewteen a moderate, yet still electrical short antenna and the coaxial feedline.
Ideally the YCCC setup was designed be a multiple-antenna phased vertical array. That said, I previously noted decent LW to 160m receive performance with just a single end-point antenna preamp and my 31' vertical. Just no directivity, and 31' is well longer than intended thus subject to increased preamp overloading. 18' is more inline with the preamp design specs.
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Thanks for your info.
I am planning to make a vertical RX antenna covering LW and MW and HF too. I have a fibreglass flag pole extending to 7m height = 21ft?
I also found 3x old slinkies in the shed which I am planning to join them all together making into one Slinky, and attach it to the pole.
I am thinking of either feeding via 9:1 balun with no ground input (just radiator input) or the other balun which has ground input making unbalanced coaxial feeding (which will feed some sort of ground wires).
I also have a MFJ preamp 1020C / Active Antenna which covers 300 kHz - 30 Mhz (actually covers from 250 kHz), which will be using to power the GP.
I am not sure the total length of the stretched 3x Slinkies, but it surely will be higher than 21ft the pole height when stretched due to its wound wire length. Hopefully it will cover from LW to 30 Mhz when powered by the preamp.
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I implemented this Slinky Vertical with 9:1 balun, and it seems working OK on LW MW and 60m tropical band.
It seems definitely working better on MW than long wire. Good to add another antenna to switch over to, when one antenna gets noisy for the night.
A few videos added into my youtube and twitter channel RXing with the DIY slinky vertical.
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In theory you probably have a end-fed normal-mode helical antenna there. "In theory" because helical antennas can be a huge YMMV depending upon diameter, turns, spacing, etc. "End-"fed" assuming no ground radial field is present. In other words, it is huge YMMV on impedance curves and resonance.
That said, the bigger problem with the standard slinky is the metal. AFAIK, most slinkies are high carbon steel, which has poor conductivity compared to copper and aluminum.
https://www.thoughtco.com/table-of-electrical-resistivity-conductivity-608499
Given the helical design considerations and metal conductivity issues involved, performance likely would fair better by simply running a copper wire up the vertical support. ;)
I suggest deploying a radial field under your vertical as well. Just a few on-ground radials of whatever lengths you can fit should suffice for receiving. If your balun does not have a ground connection, then it is probably an unun, so you could connect the ground radials to the coax connector shell on the input side. If you do not want to deal with soldering, a mechanical connection with a hose clamp should suffice.
Previously I used a simple 9' vertical over four 9' on-ground radials for quite awhile, especially back when I was using a portable receiver on the nightstand. No feedpoint baluns or transformers, though IIRC, I did have a few snap-on ferrites of whatever mix on the coax near the feedpoint for whatever they were doing; likely little to not much. It worked quite nicely (IMO) for MW through VHF, plus it even occasionally pulled double duty on a scanner for local 800MHz pulbic safety traffic. SNR was decent because it was away from the house. Gain was not a consideration, as most portables tend to overload easily anyway.
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Good point. I was a bit uncertain about conductivity of the slinky spring material, so I got out my DMM, and checked for the conductivity after joining 3x separate slinky to 1 single long slinky. The conductivity of the slinky shown on DMM was excellent with loud beeps from the end to the end. But that doesn't mean it has perfect conductivity I fear.
But it seems doing the job of RXing MW, and even LW, and some portion of HF ok. It is definitely better than the longwire on some frequencies, but not all. There are parts of the band, the slinky vertical gets very quiet, when LongWire copies well.
Great advice on the radials. Yes the balun is a 9:1 unun, and has only 1 connection post for the radiator, so perhaps some substantial radial wire will have to be added via the coax outer socket via soldering or a crocodile clip.
Through time, I will try getting different balun - with 2x separate connecting posts for the radiator (one for the radials), and keep experimenting.
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SDRangel running on a Samsung A7 Lite tablet. Airspy HF+ and active miniwhip antenna. Audio to a BT speaker.
(https://i.ibb.co/w7CSV5V/Screenshot-20230819-171528.jpg) (https://ibb.co/5kvrmbm)
SDR++ on the same config.
(https://i.ibb.co/hsfvkL6/Screenshot-20230819-190537.jpg) (https://ibb.co/PxQ8RFL)
Added the low-pass + shelving filter to my nightstand radio. More commentary here:
https://www.hfunderground.com/board/index.php/topic,118112.0.html
On a related note, I found a possible issue with a short RG-6 jumper when changing out connectors to install the filter.
Mostly just a reminder to occasionally check feedlines and connectors even if everything *seems* okay.
Estimated 148' loop-on-ground deployed. Could be closer to ~150' as I did not measure close. At least it is generally symmetrical for whatever that actually might benefit.
It is solid copper pet fence wire this time instead of RG-6 coax likely previously. It is also moved to a different position. Much of my old LoG is still floating under the surface where it was located. Not sure I want to bother finding it.
Deployed a LDG 1:1 balun at the feedpoint approximately halfway along a side. I fed my previous LoG on a side as well, so "whatever" IMO. Typically there is not enough directivity feeding a basic LoG at an apex to really matter IMO.
I was going to put a common-mode choke on the feedline near the house, but I did not feel like dealing with it tonight. Likewise I did not even bother with new run of RG-11 feedline. I found a long enough piece of bulk RG-6 with connectors in a parts bin for now.
Suppose I should get around to a basic NanoVNA sweep sometime. I did not even check the feedlines, though it all seems to be working okay.
As previously noted, I am once again thinking about moving the 31' vertical back to being ground mounted over a radial field. There is not much difference in performance for my receiving purposes other than the annoyance of ground radials. Then instead maybe look into finally deploying a small loop and lightweight rotator on the mast mount.
The new 148' LoG is not significantly better to sometimes even worse than my usual 31' vertical for EMI/RFI, at least so far tonight for MW/HF below 7MHz. I suspected that might happen, as it is closer to the house than my previous LoG and constructed with a single wire instead of my previous "shielded" coaxial design.
I can go ahead with adding a RF choke on the feedline near the house, though I doubt it will do much. Also I might look into changing the 1:1 feedpoint balun to perhaps a mix 73 isolation transformer. I suspect the 1:1 balun toroid might be a mix 43 given the size and power handling spec, but LDG does not publish the ferrite mix used.
^Merged a few posts.
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Added a RF choke on the 128' loop feedline near the house and a few snap-on ferrites below the balun at the feedpoint. Seems to have helped somewhat.
On to bigger MW/HF issues for me at the moment. The baseband noise filter in SDR# mitigates whatever the latest local RFI is for now, but I suspect it is time for a decent small loop. Tested my ~36" passive hula hoop loop with a portable in the backyard. There is considerable directivity to the particular RFI as I was able to null out most to practically all of the noise depending upon the band.
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The Cross Country Wireless HF Active Loop Antenna v4 has been peaking my intereset for the past little while. Adding their HF Multicoupler to the setup would also be a nice touch.
https://www.youtube.com/watch?v=lD3ta2j7_ps (https://www.youtube.com/watch?v=lD3ta2j7_ps)
https://www.youtube.com/watch?v=gK07qkeBl84 (https://www.youtube.com/watch?v=gK07qkeBl84)
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The RFI dropped out. I would suspect perhaps solar panels in the area, but it was dark well before the noise dropped. Hmmm.
Anyway, I dug out my antenna phasing unit in the meantime just in case.
Yeah, the CC v4 with multi-coupler is a good price IMO. I might have to take a serious look. I certainly have enough SDRs to potentially feed.
I skimmed some of the other usual suspects. Pricing for the W6LVP and MFJ-1886 loops seem to be holding decently.
Meanwhile the DXE RF-PRO-1B has jumped to ~$675 at some point. o.0
There is also the MFJ-1888, but I am not inclined to gamble $500 on a MFJ active antenna. o.0 o.0
I am hoping to score a KiwiSDR 2. I will want a decent low-noise antenna for it, especially if putting it online.
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Nothing against MFJ but I would not invest loads of money on their product. There is a catch phrase for MFJ "Mighty Fine Junk". I have owned some of it in the past and was never pleased with the quality of assembly etc ...
My name is also in on the pre-sale of the KiwiSDR 2 and think the CCW antenna would be great with it. I'm curious about running it horizontally for an omni-directional pattern. This is not something I can do with my Wellbrook or any other large loop.
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Thus the part about gambling on a $500 MFJ product.
Thankfully I have had decent luck with MFJ products, but most of those products were not hundreds of dollars, either. Checking for solder blobs and cold joints is a good idea with MFJ purchases.
The basic MFJ tuners tend to be decent, though prices there have increased as well. I like the MFJ-901B, but for $80-$90 a few years ago versus about $150 these days.
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Checking for solder blobs and cold joints is a good idea with MFJ purchases
You hit the nail on the head. I had a manual tuner once from FMJ (which was a knock off of the Barker & Williamson tuner) and the assembly was horrible. I ended up re-working the entire tuner. I also had one of their early antenna analyzer that was, well, ok, but not that great. The artificial ground box / tuner worked ok if you know how to use it properly.
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KiwiSDR 2 ordered. I not sure where order numbers started. Anyway, given how far I am likely down the list, I suppose that gives me awhile to work on an improved low(er)-noise antenna solution.
I used to occasionally hear what sounded like a plasma television during the day. I am not sure it is the same TV (or whatever), but it is back with a vengeance on my 31' vertical today. Has the plasma TV sound. The frequencies are a little different, but it has the double peak signal profile as well.
https://www.dxengineering.com/techarticles/lightningandrfiinfo/plasma-tv-mother-of-all-rfi-producers
It is highly attenuated on my 148' loop-on-ground. A little filtering pretty much knock it out there.
Thankfully the noise is gone now. Much better.
Continuing to poke at further mitigating imediately local noise.
I have (err, now had?) a storage box of TDK snap-on ferrites. Deployed many of them. They are better suited for VHF but still have some RF resistance down into HF.
Interestingly I was able to knock down some LW noise on my 31' vertical.
Notebook on mains:
(https://i.ibb.co/VC8dLt0/low-frequency-31-test-12-22-2023.png)
(click to enlarge) (https://ibb.co/B6RmftH)
Notebook on battery:
(https://i.ibb.co/cDJD8qZ/low-frequency-31-test-12-22-2023-2.png)
(click to enlarge) (https://ibb.co/72v2phZ)
I will spare the MW screenshots. Daytime would be better a test there, but anyway, there is a slight difference currently at the very bottom of the MW band. Rest of MW through HF seems largely negligible either way.
A single ferrite on an indoor RG-6 jumper to the 31' vertical did most of noise mitigation on LW and low-MW. Again it was not even a typical low-frequency ferrite mix, but FWIW, there are now four of those ferrites on that jumper. ;)
Still cleaning up RFI. Moved my both cable modem and router to a linear regulated power supply, deployed more ferrites on their various cables, and tidied up the wiring mess.
Admittedly, this is my usual notebook on battery, but a quick look at the VLF band.
(https://i.ibb.co/hFvjfvJ/vlf-band-01-05-2024.png)
(click to enlarge) (https://ibb.co/CKFZ2F3)
Moving up to LW, spotted Medi 1 with the notebook on its usual power supply. Some static crashing, but a listenable copy.
(https://i.ibb.co/NtFrZ2P/medi1-01-05-2024.png)
(click to enlarge) (https://ibb.co/k5GJQ2f)
Skimmed through the usual NDBs, and I still have annoying but expected RFI around 380KHz running on the notebook PSU. Moving up the band, thankfully the previous RFI on lower MW appears to be mitigated at the moment.
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148' loop-on-ground to a ~$30 Msi SDR with LDG 1:1 balun at loop feedpoint and KD9SV common mode choke near house entrance. Notebook on power supply.
(https://i.ibb.co/TcFpTDm/log-noise-1.png)
(click to enlarge) (https://ibb.co/sjMkPpy)
After adding an 1:1 choke wound as a 4:4 on a mix 73 binocular core near the receiver. No changes in SDR app settings.
(https://i.ibb.co/48X0R5T/log-noise-2.png)
(click to enlarge) (https://ibb.co/D9vjfSC)
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Nice clean up with the 4:4 (1:1) UNUN.
For those who have not been following the entire thread, to recap, below are some of the effective frequency ranges for the various ferrite MIX values.
MIX 31 - 1 MHz - 300 MHz
MIX 43 - 25 MHz - 300 MHz
MIX 73 - < 50 MHz
MIX 75/J - 150 KHz - 10 MHz
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Yeah, more or less an isolation transformer due to using galvanically isolated windings. I have used them previously on other antenna projects.
I like the small mix 73 binoc cores for MW/HF receiving purposes, especially for the cost. Add enameled magnet wire and a couple of cheap F connectors. Maybe an $1 or so in build materials.
I have been needing to build more, but that means soldering, which is not exactly on my list of favorite activities these days.
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Snap a close-up picture some day once you have a completed version. I would like to see your build.
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Well, this looks more convenient than that godzeyes antenna that I've made. https://swling.com/blog/2024/01/video-giuseppe-explains-wiring-construction-of-dica-homebrew-antenna/ Tis the season to build and try stuff.
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I will try to post pics if/when assembling another one. I did not even bother with a board or enclosure this time. Instead I just used heat-shrink tubing to hold the F connectors on each end, and that tends suffice for an indoor transformer that is not going to moved around a bunch.
I left a comment on his other ferrite antenna blog post:
https://swling.com/blog/2024/01/d-i-c-a-giuseppes-latest-homebrew-portable-antenna/#comments
Seems you can get away with a rather small type 61 ferrite even well above the tropical bands if opting for preamp stage. This design suggests possibly up to 12MHz:
http://www.jumaradio.com/active-ferrite-rod-antenna/active-ferrite-rod-antenna.html
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No worries on the pictures. I was just curious what you had used to construct the transformer since you were mentioning magnets.
You did get me going out looking at antenna galvanic isolators again. I have always been interested in the Bonito but I find that it is expensive.
I did come across a couple of interesting links. Heros Technology has a unit which you can transmit into (200 watts) and has low insertion loss. They also have some good pictures and PDFs on the site.
The other is from RF SYSTEM. Download the PDF from the link below. This is very close to what you are building. They use a transformer from MINICIRCUITS. I find that the insertion loss on this transformer is high (1 dB). Maybe MINICIRCUITS has a better transformer than the one selected for this product.
Heros Technology
https://www.herostechnology.co.uk/pages/RF_Galvanic_Isolators.html
RF SYSTEM
http://www.rfsystem.it/ (http://www.rfsystem.it/)
http://www.rfsystem.it/pmsdr/files/Antenna_isolator.pdf (http://www.rfsystem.it/pmsdr/files/Antenna_isolator.pdf)
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Fair-Rite BN73-302 (2873000202) mix 73 binocular core. Currently ~$0.68 each at DigiKey and Mouser. Four turns on the antenna side. Four turns on the receiver side. I have seen some mentions of trying 5:5 as well, though 4:4 usually seems to work fine for my purposes.
My noise usually tends to be lower-HF downwards, so I generally favor the BN73-302. Fair-Rite has an affordable mix 43 binoc (2843000102) as well. Not sure I have ever seen a mix 31 binoc.
A possible alternative to the BN73-302 might be a TDK N30 binoc core. I keep planning to try N30 ferrites, but I have yet to order any.
https://dh1tw.de/2021/06/whats-the-best-ferrite-material-for-a-common-mode-choke/
I am not too concerned about insertion loss, especially for receiving under 10MHz, as even my loop-on-ground has plenty of signal for its intended operating frequency range.
Curious, have you skimmed any of Coilcraft's offerings? It has SMT transformers usable at MW/HF frequencies rated down to 0.2dB insertion loss assuming that is a concern. There are some through-hole models as well, but I did not see printed loss numbers in a quick skim.
https://www.coilcraft.com/en-us/products/transformers/wideband-rf-transformers/#/
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Very nice on the Coilcraft offerings. I was not aware of them. It looks like a WB1010-PCL, WB2010-PCL or WB3010-PCL (0.005 to 100 MHz) would do the job for HF. Thanks.
Here is a link with a comparison of response vs. number of turns. I wish I could make heads or tail of those frequency charts. What a horrible way to express the frequency.
Measurements of some transformers for low-bands antennas
https://www.qsl.net/in3otd/ham_radio/160m_transformers/160m_trafos.html (https://www.qsl.net/in3otd/ham_radio/160m_transformers/160m_trafos.html)
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Took a quick skim. I have a degree in math, and yeah, even I think simply stating for example 10MHz is much more readable than 1e7 (1x10^7) Hz.
The "braid breaker" design is showing measured losses for 2:2 isolated straight windings on mix 73 should be okay for LW to mid-VHF, though I noted he is using two stacked binoc ferrites. Correlating against his bifilar charts, it would seem 3:3, 4:4, and 5:5 on mix 73 should have little real-world differences for MW/HF losses.
Looking at the capacitance chart, with ranges of 0-5pF and 1-100MHz, I would think the measured numbers are low enough at those frequencies to be largely trivial unless doing a tuned circuit.
With the mention of a tuned circuit, the idea of doing a remotely tuned HF receiving loop using a varactor circuit is somewhat interesting. For example:
http://techlib.com/electronics/antennas.html
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The circuit fits nicely in the standard PVC junction box although I would question the use of braid as an antenna conductor for the same reasons that braid is not ideal for grounding.
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Lots of loop antenna designs use coaxial braid, but I agree, especially since a 10' roll of 3/4" soft copper refrigeration tubing is like $10 to $15 at Lowes and similar. That is about the same cost as 10' of bulk RG-8/213.
Aluminum should suffice as an alternative as well, especially considering a preamp is used in the circuit. Here is a rather simple varactor-tuned loop based upon the previously linked design, but using Al tubing:
https://sivantoledotech.wordpress.com/2010/09/18/a-tuned-active-receiving-loop/
Noted some RNoted some RFI tonight. Brought my hulahoop loop on a tripod inside. Using upper MW as a test band, I could null much of the RFI, so it is likely somewhere in the area.
Just got back to the radio, and the RFI is gone now at ~0750z.
Anyway, in the meantime, I did manage to toss together a mix 73 isolation transformer on piece of perf board to replace the temporary one I built a few days ago.FI tonight. Brought my hulahoop loop on a tripod inside. Using upper MW as a test band, I could null much of the RFI, so it is likely somewhere in the area.
Just got back to the radio, and the RFI is gone now at ~0750z.
Anyway, in the meantime, I did manage to toss together a mix 73 isolation transformer on piece of perf board to replace the temporary one I built a few days ago.
31' vertical without mix 73 isolation transformer near receiver. Notebook on power supply.
(https://i.ibb.co/VBjfy2H/without-isolation-transformer.png)
(click to enlarge) (https://ibb.co/0JDHNhB)
31' vertical with mix 73 isolation transformer near receiver. Notebook on power supply.
(https://i.ibb.co/yPnFMTG/with-isolation-transformer.png)
(click to enlarge) (https://ibb.co/7CJtTc8)
Not that I actually recommend using a 31' vertical for VHF reception, but I did take a quick look at area NOAA broadcasts with and without the transformer. SDR floor and peak numbers suggest around 2dB or so of transformer loss at mid-VHF frequencies. Factored against typical mix 73 characteristics, that would suggest LW/MW/HF losses are likely quite negligible.
Thought I might have to look at the feedline and the hybrid feedpoint unun on the 31' vertical, as my 148' loop-on-ground even with its incurred losses was showing considerably more gain on many bands. o.0 Tightened various connections on my inside feedlines. Thankfully it seems back to normal.
I do need to replace an antenna switch. I have one of those inexpensive CATV slide switches in line with my Airspy HF+D.
I still have that WiFi remote antenna switch collecting dust on a shelf. It passes DC from the bias tee to the antenna ports, so I would it would need DC blocking caps. Suppose I could add the caps internally, but taking the hopefully easier route, I just ordered some CATV DC blocks to try first.
(^Merged posts.)
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I suspect the screenshot below is about as good as the 31' vertical is going to get at VLF during the daytime with my usual notebook running on a switching power supply. The noise floor is approaching -130dB on 60KHz,
I added a -3dB attenuator (for now?) between the coax switch and mix 73 isolation transformer, of which the other side connects to my Airspy HF+D via a RG-316 jumper wound on a (mix 43?) snap-on ferrite. I probably could get away with more like a -10dB or even a -20dB attenuator (on some bands) to perhaps slightly help with some of the mismatches involved.
(https://i.ibb.co/MVVd3Mj/wwvb-01-21-2021.png)
(click to enlarge) (https://ibb.co/VSS6P2h)
On a related note, I added (IIRC) a -10dB attenuator to the active miniwhip feeding my nightstand receiver as well. I need to check it again, but in a quick skim, it seems to have helped to further clean up the cheap MSI SDR being used there.
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Nice clean-up. Is it the power supply or the notebook generating the noise? The reason I ask is because my IBM ThinkPad is similar. Although the switching power supply is noisy when I plug it into the laptop the entire laptop becomes an enormous source of noise, more so than the power supply.
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It is mostly the power supply. I have two HP 150w notebook PSUs. The -130dB screenshot is a somewhat older model after deploying the various antenna, feedline, etc RFI mitigations..
Last time I checked I seem to remember the newer model pretty much being a RF generator. o.0 I keep intending to modify the noisy one, but it apparently is not high on the priority list.
I was considering migrating to a 19v linear PSU, but it seems largely mitigated for now, at least for my 31' vertical. Perhaps later.
On a higher priority note, I need to get around to sourcing a decent 5v PSU for the KiwiSDR2 on order.
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Plenty of reasonable choices on eBay for the power supply.
Lambda LNS-X-5-OV power supply 5 vdc 10 amps out.
https://www.ebay.com/itm/293812347657 (https://www.ebay.com/itm/293812347657)
Lambda LDS-P-5-OV Massive Linear Power Supply +5v DC 22A
https://www.ebay.com/itm/275385083025 (https://www.ebay.com/itm/275385083025)
Lambda LP-520-FM Regulated Power Supply 0-10VDC 3.7-5.0A
https://www.ebay.com/itm/266607613314 (https://www.ebay.com/itm/266607613314)
Hewlett Packard 62005E DC Power Supply 8 Amp 5vdc
https://www.ebay.com/itm/304807918132 (https://www.ebay.com/itm/304807918132)
HP6281B Bench Variable Power Supply 0-7.5V 0-5A
https://www.ebay.com/itm/134002920421 (https://www.ebay.com/itm/134002920421)
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A quick skim of specs for the Lambda LNS-X-5-OV looked pretty good IMO. Ordered.
I redid some inside feedlines and removed the -3dB attenuator on the Airsphy HF+D feedline. LW/MW on the 31' vertical still seems okay. WWVB and sub comms present. Medi 1 on 173Khz is there but largely buried in static crashing tonight.
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Excellent on the power supply. One thing with the Lambda power supplies is that most are ment to be mounted as part of a piece of equpiment so they do not have any on/off switches and are un-fused. Make you you add your own in-line fuses for protection.
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Yep. I figured on picking up an used Acopian, Allen-Bradley, or similar power supply anyway. Lambda works for me. Supposedly NOS as well. Thanks for the link.
The DC blocks arrived. Did a quick test on a SDR. No immediately noticeable insertion loss on MW/HF.
There appears to be a little loss down in lower LW under probably 100KHz, though I did not care enough break out the NanoVNA to measure.
Hardly surprising IMO, as they are inexpensive DC blocks for CATV. Anyway.
Here is an interesting one. My nightstand receiver is basically a small WinARM notebook, an inexpensive MSI SDR, and an active miniwhip.
IIRC, the bias tee probably already has an internal isolation choke. though I did not bother testing it. Instead I added a mix 73 binoc ferrrite with like 3-4 bifilar turns on the antenna side just in case.
Not bad but still some weak evenly spaced lines in the waterfall. Likely from the notebook and/or SDR. Dropped the PSU, which I already know is somewhat noisy at low frequencies, yet they were still there. Touched the metal case of the SDR, and they mostly disappear. Now I am getting somewhere.
Tried adding a mix 73 binoc ferrite wound as an 1:1 isolation transformer near the SDR. No real help there, so it is not coming from upstream, which is not too surprising if the bias tee likely already has a choke.
Okay, what if it is actually a ground loop or similar causing the issue? I grounded the SDR back to the power strip ground. The issue is now mitigated.
A some point I should get around to moving the feedline to a passive antenna as well, but the nightstand SDR is mostly for background noise, so "whatever" for now.
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Okay, what if is actually a ground loop or similar causing the issue? I grounded the SDR back to the power strip ground. The issue is now mitigated.
Nasty. I wonder if the enclosure is actually floating (un-grounded)? Do you have an AC line isolation transformer that you can put before the power strip to see if that also removes the noise? I have isolation transformers in front of most of my gear so ground is actually ground and not neutral bonded to ground.
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There is an ESP XG-PCS-15D power filter before the power strip.
Interestingly enough the issue persisted even on battery, and IIRC, the linear power supply feeding the bias tee disconnected . I suspect it is internal to the ~$30 SDR. ;)
https://revspace.nl/Msi2500SDR
https://github.com/EndlessEden/msiSDR/tree/RSP1-S
Mine should be "full" variants since they have the five bandpass inputs and came with enclosures, though I have not directly verified the circuit layout through disassembly. I am not too concerned either way as they are mostly used to casual HF listening. That said it would not surprise me if the PCBs are not effectively grounded to the enclosures.
The RTL-SDR V4 for $30 pretty much makes its older V3 sibling and most of the MSI variants kind of pointless for HF anymore IMO. I have not got around to poking at rtl-sdr-blog drivers on Windows ARM, thus why I have a MSI SDR connected to my nightstand receiver.
Ideally I probably should get my Kenwood R-2000 back on the nightstand. Problem there is needed troubleshooting I have not felt like doing, or I might eventually send it out for repair. I suspect a damaged FET in the first stage.
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I'm glad that I am not the only crazy one with a receiver on my nightstand. That is the home for my ICOM IC-R75 and mini-whip antenna. The antenna is currently inside the house hanging in the window frame. I picked up a "through window" flat cable back in December and plan to move the antenna outside once the weather gets nice again. You probably guessed it, the antenna is powered by a small HP 6216A power supply and the entire AC power path runs through a ONEAC CL1101.5 power conditioner.
The R75 is perfect for this application because the LCD colour is perfect and the brightness is adjustable plus is has a "sleep timer" function. I usually set it to 1 hour then it turns itself off automatically. My BelkaDX and Sony ICF-SW7600 work equally well when travelling.
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Need to check the 31' vertical. Signals are way down. Suppose I will start with inside jumpers and work my way from there. Fun stuff.
Resolved. Appears to either have been the jumper to the KD9SV common-mode choke right outside the house, or it could be the choke itself. I just removed them on both my 31' and 148' loop-on-ground for now.
I probably should replace the chokes with galvanically isolated chokes anyway.
Seller cancelled the 5v power supply order. Oh well.
Ordered a Lambda LCS-CC-5-O with a LHOV-5 over-voltage protector installed. It is way oversized for my purposes at up to 16A capacity, but it was decently priced.
https://www.us.lambda.tdk.com/products/legacy-products/pdf/lc_fall85.pdf
https://www.artisantg.com/info/TDK_Lambda_LMOV_LHOV_Overvoltage_Protectors_Manual_202012135713.pdf
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Seller cancelled the 5v power supply order.
Scoop up those power supplies while they are available at reasonable prices and before greedy vendors figure out that there is a potential increase in demand driving up prices.
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Audiophile and SBC enthusiasts have driven up demand for 5v linear power supplies. There are lots of new models from China flooding into the market in recent years. My concern is the specs, or more often like the lack thereof. "Low noise" does not mean much IMO, and reviews can be all over the place as well since parts can change from production run to run.
Anyway, yeah, I am with ya'. At least the older supplies for lab, plc, and other precision uses are typically "known quantities" with often many years of stabilized designs.
The Lambda LCS-CC-5-O I ended up ordering is older and used, but I suppose if it does eventually need work like new caps at least most of the parts are probably through-hole. SMD parts and my hands really do not go well together anymore.
Speaking of linear power supplies, I recently moved my cable modem and network router to one. Probably no real difference, but it eliminated two more switchers.
Seeing as my 31' vertical seems to be doing decent at lower frequencies, I took a skim of VLF frequencies after midnight EDT.
18.3 HWU Le Blanc, France
21.4 NPM Lualualei, Hawaii
23.4 DHO38 Rhauderfehn, Germany
24.8 NLK Seattle, Washington
25.2 NML LaMoure, North Dakota
40.0 UNID (seriously doubt JJY Tamura, Japan ;p )
40.7 NAU Aguada, Puerto Rico
45.9 NSY Niscemi, Italy
52.0 UK Navy?
60.0 WWVB Fort Collins, CO
62.6 FUG La Regine, France
65.8 FUE Kerlouan, France
77.5 DCF77 Mainhausen, Germany
162.0 TDF / ALS162 Allouis, France
198.0 BBC4 carrier / UK-AMDS
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Good RX on that vertical. I don't see most of these from my location. It may be time for me to put up a vertical and see what happens.
You will find the manual for your Lambda LCS at the following link:
https://bama.edebris.com/manuals/lambda/lcs-a (https://bama.edebris.com/manuals/lambda/lcs-a)
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Some longwave NDB loggings as well:
https://www.hfunderground.com/board/index.php/topic,124922.0.html
An outdoor remote-tuned ferrite loopstick probably would fare even better at longwave and below, but a simple vertical with even limited RF grounding tends to suffice at low frequencies assuming it is not completely swamped with local RFI/EMI.
I remember my 31' having quite impressive (to me anyway) low-frequency performance with a YCCC preamp. Instead of outright gain, the YCCC feedpoint preamp is designed to improve matching an electrically short antenna to a low-impedance coaxial feedline. Worked nicely for that, but it overloaded on some HF bands. It was not intended for a 31' vertical with a radial field back when I have that antenna ground mounted.
Occasionally I think about redeploying the YCCC preamp, but with a 9' or an 18' vertical element over a single ground rod as intended by the designer.
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The 5v linear power supply needs work. Transformer seems okay. Recapping is not too big an issue, though i will have to order some of them.
The power transistors could be an issue if they need replaced. I still need to test them. The four currently installed ones are around $30 a piece. Skimmed some potential equivalents. A few possibilities are under $10 a piece, so I probably will just swap them all if there are failed ones.
Now to check through my 5v USB switchers for maybe a temporary workaround.
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Wasn't that power supply listed as tested / working?
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Not really sure. Lots of these types of devices are pretty much described "pulled from working environments." That tends to be more like "roll the dice" IMO.
Even if I have toss a few repairs at it, I suppose whatever, as a large 5vDC 16a linear power supply is kind of a pricey item be it new or used. IIRC, this model was nearly $600 back in the day. Barring a complete replacement of all primary power transistors, I probably can come out with like $100 or so invested.
In the meantime I likely will go pickup an Apple USB-C power supply for under $20. If needed a multi-stage EMI filter is around $10 to $15 on eBay. Doubt I would bother trying to build a filter board for that price.
I need to catch up on my browser builds this weekend. then hopefully I can get back to playing radio later this week.
On a positive and more affordable radio project note, I was next to a Dollar Tree store awhile back. A box of medium-size hula hoops was on the sidewalk. $1.25 a piece. I purchased a few for antenna projects.
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My KiwiSDR 2 is working. :) It is not public at the moment.
Local store was out of Apple wall warts. Found a Samsung USB 3A power supply at home. It has a little noise at a couple of spots in the HF spectrum, even with some ferrite choking, but it suffices for initial setup and testing.
Seeing as I did not get around to rerouting feedlines, I setup an old WiFi router running DD-WRT for a wireless client bridge to my LAN. I did use a linear power supply there. ;p
Hooked up my 31' vertical. Been listening to 80m amateur radio in the background. Some moderate to strong static crashing from area storms, too. Anyway.
I still need to tweak the s-meter and waterfall calibrations. I will likely dig out my RF shelf filter from some added roll off under 10MHz to potentially better equalize the 0-30MHz wide waterfall.
Tearing further into the Lambda 5v 16a linear PSU is low to no priority at the moment.
In the meantime I have ordered a couple of affordable used 5v 3A hybrid regulated power supplies for experimentation.
https://www.digikey.com/en/articles/hybrid-power-supplies-deliver-noise-free-voltages-for-sensitive-circuitry
Semiconductor Circuits ES5S3000 (EC11-300) PSUs in particular.
https://www.datasheets360.com/pdf/5490670810123532253
Plan to use a Schaffner FN9222-3-06 on the AC side, then a Schaffner FN2090-3-06 on the AC, DC, or both sides as needed.
https://www.schaffner.com/product/FN9222/Schaffner_datasheet_FN9222.pdf
https://www.schaffner.com/product/FN2090/Schaffner_datasheet_FN2090.pdf
Probably will salvage an old ATX power supply for an enclosure.
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This is my Schaffner EMI/RFI filter arrangement.
(https://i.postimg.cc/9fjKWX8K/Schaffner-EMI-RFI-Filter.png)
I also incorporated a fuse on the line side in the later design thinking that if something was to go wrong with the filter then it could present a dead short all the way to the fuse/breaker panel. I also recently seen a video where someone put 77 and 43 ferrites (5 ~ 8 turns ea) on the input and output leads and that had a significant improvement on reducing noise. You are obviously look at larger core ferrites and a much larger enclosure. None the less, if you get a 15 amp or more Schaffner then it might be worth the effort and filter out an entire 15 amp branch circuit.
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I used to basically assume 120v 15A drops as well, but IIRC, the 120v drops in this house are 20A. Built around 2004.
Anyway, yeah, filtering a whole branch is tempting. I have even considered an isolation transformer on a specific branch for certain equipment.
My most immediate annoyance is a moderate increase in the local noise floor, and sadly, there is not much I can do about it. My community continues to grow with many new home constructions in my immediate neighborhood. Suppose I should be thankful most of the homes are concrete block with stucco over wire, with the house electrical ground typically being the rebar in the concrete foundations, so there is some EMI/RFI dampening already present in the construction designs.
I was able to find a deep null in the noise floor playing around with a passive loop outside awhile back. I am thinking about feeding the KiwiSDR 2 with such a passive small loop for now. Kind of directional and admittedly "gain" well into a few dozen negative dBs, so it is going to "miss" some weak signals, but I would rather it have the low noise floor especially if eventually putting a couple of the channels online.
Update. Forget the active miniwhip. Here is the KiwiSDR 2 and 31' vertical. Skimming upper HF at the moment.
(https://i.ibb.co/RYvsmxV/11m-activity-03-05-2024-2.png)
(click to enlarge) (https://ibb.co/4KmXG65)
Stats are showing 23dB SNR overall at the moment, which is about average for the KiwiSDR network. Area storms, local daytime RFI, and the USB wall wart are not helping.
I am running a RF shelf filter with -20dB rolloff under 10MHz. I still need to tweak the waterfall and meter calibrations a little more.
(https://i.ibb.co/rFn1BFJ/kiwisdr2-03-05-2024.png)
(click to enlarge) (https://ibb.co/hLptGLv)
The horizontal lines are static crashes from area storms. No noise blanking enabled right now. Anyway.
There is a slight dip in the tropical bands, but at least 0-30MHz does not look quite like a roller coaster. ;)
I so "enjoy" when that wideband signal pops up. I set the waterfall to somewhat better highlight it.
It is from approximately 6825 to 6975 in the screenshot. It is now about 75KHz higher.
(https://i.ibb.co/SdzmNp5/wideband-signal-03-10-2024.png)
(click to enlarge) (https://ibb.co/s6Z1jrb)
My KiwiSDR 2 is reporting 34dB SNR tonight. That is more like it. That said, it is still on the 31' vertical, plus the dishwasher is running right now. o.0 Anyway.
APC LineR ---> cord --> Schaffner FN9222-3-06 --> Schaffner FN2090-3-06 --> Semiconductor Circuits ES5S300 5vDC 3A bybrid PSU --> ferrite choke --> cord --> ferrite choke --> KiwiSDR 2
The power supply, Schaffner filter, fuses, etc. are in an old ATX PSU case. Even wired up the couple of cooling fans at 5vDC FWIW, and they are quiet for both sound and RFI.
I tried both a Schaffner FN2090-3-06 and a homebrew filter on the DC side. Either delivered 5vDC to the Kiwi, but it would not boot. Hmmm. That is why the ferrites are there for now.
The Kiwi has been reporting an overall SNR around the low to middle 30s range. It is still on my 31' vertical. Any further SNR improvements are likely going to be on the antenna side.
VLF and LF look decent IMO. No noise blanking needed (at the moment?).
(https://i.ibb.co/8XWPBjs/kiwi-03-13-2024.png) (https://ibb.co/fQhrSCF)
Approximately 9' mobius loop active antenna. it is on a tripod in the den right now. It is not even near a window, and I did not bother much with even trying to null noise.
The loop is RG-11. The upper mobius crossover was salvaged from a Youloop, repaired, and potted.
The amp is packaged in a larger enclosure with SO-239 connections. The amplifier is from a MLA-30. ;p It can be changed out later for something better if desired.
on the active loop
I have a 10dB attenuator before the Airspy HF+D at the moment as the amp has plenty of gain at lower frequencies. I will work on tweaking that later.
(https://i.ibb.co/44qLdJy/active-loop-03-18-2024-2.png)
(click to enlarge) (https://ibb.co/bN0VJ7h)
(https://i.ibb.co/1Mr019c/active-loop-03-18-2024.png)
(click to enlarge)[ (https://ibb.co/7QnSPGh)
(https://i.ibb.co/3hFT27d/active-loop-03-18-2024-3.png)
(click to enlarge) (https://ibb.co/yskNtXP)
(https://i.ibb.co/Bn60CP0/active-loop-03-18-2024-4.png)
(click to enlarge)[/urlg
(https://ibb.co/8Yx17B1)
The active loop is outside now. Around 8' off the ground. RG-11 feedline.
I simply turned it to get a general null one of the usual more noisy parts of the HF spectrum here.
Nulls are vaguely somewhere around WNW/ESE to NW/SE. I did not check a compass.
Gain is not uniform, but I expected that. Longwave is likely a huge YMMV. Both are aspects of the MLA-30 amp board.
A mix 73 isolation transformer between the bias tee and SDR helped clean up noise on lower MW and much of longwave, though actual LW signal reception remains a question mark.
The ~$30 HFDY loop kit at Aliexpress and similar could be of potential interest. It is based upon a simplified LZ1AQ-based amp design. Appears to use a 2SC3357, or perhaps a clone. No regulator. No lowpass filter. YMMV.
More details including measurements:
https://groups.io/g/loopantennas/topic/hfdy_chinese_loop_and_loop/103801226
Clone or real, the results look (much) better than the inexpensive video amp typically used in the MLA-30 and related designs.
FWIW, I have WWV on 2500, 5000, 10000, 15000, 20000, and 25000 at ~0140z on the active loop.
No 60Hz on the active loop. As suspected not much happening on longwave and lower with the MLA-30 amp board. Anyway.
Seems I picked the wrong noise source(s) when tweaking the loop direction. The nulls are now more ENE/WSW.
The current daytime noise floor difference on the 40m band is about 2-3dB with SDRSharp noise blanking enabled.
The NNW peak should favor more of North America. Works for me regarding that particular antenna.
The other noise source is towards 8MHz, along with intermittent and variable in strength. Noise blanking largely knocks it out, so I will try to just disregard it for now.
I might have an idea of what one of the noise sources is. I need to verify, so perhaps more to follow.
Suppose my days of HF radio are about done unless I can find the current area noise source(s), It is does not appear to be local to my house.
S5+ noise on 40m even on my LoG, which is in tens of dBs loss by design.
Replaced the preamp with a mix 73 1:1 isolation transformer for the 9' mobius loop. Not much different than the LoG.
Overall SNR on my 31' vertical is down to 19dB with noise.
Even have some EMI/RFI at ~28MHz on my 18' end-fed vertical.
I can still listen to lots of signals, but weak signal reception is trashed. That pretty much takes the fun out of HF listening for me.
Moved location and dropped the now passive 9' mobius loop down to maybe a foot or so off the ground. I am trying to use ground losses to cancel out some of the noise. It helped on several bands.
The noise source dropped out. I am hoping it is not an area solar power install.
My Kiwi with 31' vertical is reporting 34dB SNR.
As for the loop, the 9' NCPL is now about 18" off the ground. Current 7MHz noise floor is floating around S2 with my Airspy HF+D. SDRSharp noise blanking does not effect it.
I probably will have to realign the loop if/when the noise comes back. There was not much else to null tonight, so I just put the peaks back to roughly NNE/SSE.
At approximately 0145z to 0200z tonight with some static crashing from storms in the gulf.
1110KHz | -134dB noise floor | WBT 38dB SNR
5MHz | -116dB noise floor | WWV 41dB SNR
10MHz | -122dB noise floor | WWV 57dB SNR
20MHz | -138dB noise floor | WWV 54dB SNR
Noted at least couple of longwave BCB carriers. Also WWVB.
60KHz | -131dB noise floor | WWVB 22dB SNR | notebook on mains
60KHz | -139dB noise floor | WWVB 20dB SNR | notebook on battery
The NCPL feedpoint is using a mix 73 1:1 isolation transformer, plus there are a few snap ferrites on the RG-11 feedline. Also a few snap ferrites on the feedline near the SDR.
It was dark outside, so I called the antenna project for the night.
Static crashing is horrid tonight, but otherwise the noise situation seems perhaps a little better.
The 9' NCPL needs more feedline decoupling at the loop feedpoint. Suspected it might as I used only a single mix 73 binoc. It probably needs two or more cascaded. Something to poke at later.
I already knew the 148' LoG needed more choking when it was deployed. I replaced the LDG 1:1 (of whatever mix) with a Noolec 9:1 v2. The ratio is little high, but anyway, it further cleaned up mediumwave and lower for now.
Also I reconfigured some inside chokes and filters. I am back to having WWVB 60KHz and area longwave beacons during daytime on my elevated 31' vertical.
It is getting to the point of wanting more directivity than just a small bidirectional loop. I am thinking about building a SULA and deploying it on a rotator.
https://swling.com/blog/tag/sula/
https://swling.net/viewtopic.php?t=55
BTW, I am done playing with 5v power supplies for awhile. I just ordered a new (open box) Acopian VA5H3200. That is an A5H3200 with overvoltage protection.
https://www.acopian.com/store/productdetail.aspx?q=i284
https://www.acopian.com/inc/streamFile.asp?loc=info&id=AcopianCatGoldBoxLinear.pdf/
Current at 40°C: 32 amps
Load Regulation: 0.005+/- % or 2mv
Line Regulation" 0.005+/- % or 2mv
Ripple: 0.25mV RMS
BTW, I suppose the hybrids were not bad for the price, but they were still not quite what I wanted.
Today I noted a new solar panel installation on the next street. The direction appears to correlate with one of the annoying daytime noise sources, and the 20KHz spacing lends further support to a potentially noisy inverter.
The 9' passive loop is back to elevated. Maybe 7' or so. Added more feedline choking.
I have other mixes of toroids on order to potentially further modify the feedpoint transformer.
I might also experiment with changing it to a shielded loop. All I have to do is swap the mobious crossover at the top for a short coax jumper with a shield break.
Ordered an HFDY loop. I pretty much simply want the amp board, but anyway. ~$30 for an assembled LZ1AQ-based loop is decent IMO.
As noted earlier, the HFDY loop amp lacks a low-pass input filter, has no onboard voltage regulator, and has lower OIP2/OIP3 performance than more expensive LZ1AQ designs.
1. A 30MHz low-pass filter between the loop and amp is not difficult to implement, but I doubt it will be needed at my QTH. I have tested rather large antennas and cheap high-gain preamps without noticed FM overload here.
2. A voltage regular on the amp board is not really required if using a decent power supply. I can do that so whatever IMO.
3. The OIP2/OIP3 is still okay enough for my intended mostly HF purposes. At any rate the OIP3 as measured appears to be around 9dB better than the first-gen NE592-based MLA-30 amp board.
On a tangent related to the MLA-30, I ordered a couple of inexpensive NE592 preamp boards as a starting point for some further experimentation. Basically this in the through-hole version but without the bias tee components:
https://www.pcbway.com/project/shareproject/Antenna_Magnetic_loop_on_video_amplifier_NE592_DIP_version_10ff2fb5.html
They might prove useful enough for later projects after a little work on the input and output sides.
^Multiple posts merged.
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Today I noted a new solar panel installation on the next street. The direction appears to correlate with one of the annoying daytime noise sources, and the 20KHz spacing lends further support to a potentially noisy inverter.
By now, most installers are aware of the potential noise that the inverters can create. I seem to recall seeing something on TV, might have been on "Ask This Old House" about solar panel installations. Installers are supposed to mitigate the issue so I would approach them sooner than later to bring it to their attention.
Electrical noise pollution is a big issue.
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My luck it could be a DIY install as there are are not many panels involved. I still need to check it further with a SA or at least a portable receiver, as admittedly, it might not be related given the number of new houses popping up in my neighborhood.
Perhaps 40 acres in a remote Wyoming location would be the better radio listening solution for me. o.0
Dropped my 31' vertical back down to the previous ground mount location. Same ~2.5:1 hybrid dual-core unun at the feedpoint. Just a ground rod without radials for now as it got dark outside. RG-11 back to the house.
The hybrid unun as designed was intended for a wideband end-fed vertical antenna with minimal RF grounding anyway. It seems to be doing okay so I might forget the radial field for awhile.
The noise profile already looks better IMO, though it is nighttime so I suppose the real check will be tomorrow during the day.
Skimmed multiple bands. I have WWV(B) time signals on 60, 2500, 5000, 10000, 15000, 20000, and 25000 at ~1:30z using the 31' vertical. :)
KiwiSDR 2 at default dB calibrations. 31' vertical fed with a dual-core hybrid unun against a ground rod. -10dB shelf filter under 10MHz.
Acopian VA5H3200 5vDC 32A regulated linear power supply. Straight to the plug on each side. No extra mains filtering, ferrites, etc.
Only 15dB SNR during mid-day as I post this message, versus my Kiwi often reporting in the mid-30s at night even on its previous switching power supply. A loop with the HFDY LZ1AQ-based preamp I have on order might improve the daytime number.
I am using an old router running as a station bridge for testing the 5v PSU. It is on a 12v linear regulated power supply, but the router itself could be contributing to a little longwave noise. I did not bother with ferrites on the LAN cable, either.
Mediumwave:
(https://i.ibb.co/b22744W/kiwisdr2-04-2024-01.png)
(click to enlarge) (https://ibb.co/P99t22m)
Longwave:
(https://i.ibb.co/2ZQZjyr/kiwisdr2-04-2024-04.png)
(click to enlarge) (https://ibb.co/GHLHV0D)
269KHz is GN in Gainesville, Florida.
(https://i.ibb.co/yFnfnvc/kiwisdr2-04-2024-02.png)
(click to enlarge) (https://ibb.co/60RnR97)
40.75KHz is Navy NAU in Puerto Rico.
(https://i.ibb.co/6rGJbhs/kiwisdr2-04-2024-03.png)
(click to enlarge) (https://ibb.co/q7hF9G1)
Here is that "wonderful" 15dB SNR during the day. This is with noise blanking and tweaking the waterfall to better hide some of the noise. I have seen much worse, but yeah, it is not great IMHO.
(https://i.ibb.co/5BkDcm6/kiwisdr2-04-2024-06.png)
(click to enlarge) (https://ibb.co/bzFhdTP)
Again I am hoping the situation improves with a loop actually having moderate decent nulls. Also I still need to check RFI near that house with the solar install.
BTW, noise blanking is one area where I find SDRSharp excels with the Airspy HF+D. Really can comes in handy when needed.
Need to find one of my radial plates, but anyway, there are four ~31' ground radials now under the 31' vertical. It is start.
Tossed this small recharable hi-z preamp on the 15' loop in a window currently feeding my Tecsun PL-330.
https://www.ebay.com/sch/i.html?_nkw=High+Impedance+Amplifier+Donut+Antenna
Bought mine on AliExpress for ~$16. eBay was just easier to search on my tablet.
It is designed for impedance matching instead of any appreciable gain. Not sure it helps much on MW in a very quick skim of the band, but seems to be doing decent on HF in my limited testing.
An ETM scan of HF BCB bands returned 93 possible stations at 0139z. Noted an image at 2360, but that could just as well be the portable radio. Otherwise I have been listening to MRI, Wolverine Radio, and even some 75m amateur radio as I type this post. Not bad for a portable and indoor antenna IMHO.
Probably would be a decent addition to a small loop or wire antenna for portable HF listening at the beach, park, etc.
Received the LZ1AQ-based HFDY loop kit as well. Wanted to make sure the preamp board works. Deployed the kit in a window, set it to be a shielded loop, and powered it via a 9v battery. Hooked up to my Tecsun PL-330.
A skim of MW is pointing towards decent potential.
I will need to hookup a SDR to check LW.
At ~0500z....
Various European ops working 40m DX and whatever contest.
An op in the Canary Islands working 80m.
On a lark since the HFDY does not have a lowpass filter, an ETM scan of FM BCB band returned 82 possible stations compared to 67 on the radio's own whip.
Experimenting with a couple of TDK ferrite mixes. Trying a N30 toroid and a T65 toroid in series with 10 turns of RG-174 on each.
https://www.tdk-electronics.tdk.com/download/187204/fd7b13cb06de3e2edca6c617ac9de7da/pdf-n30.pdf
https://www.tdk-electronics.tdk.com/download/528846/1598c89da613db594840e493e0ffb9fe/pdf-t65.pdf
I should test the setup with my NanoVNA, but anyway, a quick waterfall skim of 0-30MHz looks decent for a common-mode choke without galvanic isolation.
Exmaple of lower LF with WWVB. Notebook on battery. Airspy HF+D and 31' vertical.
(https://i.ibb.co/bB4b5tS/tdk-ferrite-test-04-21-2024.png)
(click to enlarge) (https://ibb.co/9TxZHPF)
I figure this choke will end up near the feedpoint of my HFDY loop if/when I get around to deploying it.
I obtained TDK N30 binoc ferrites as well. I suspect they likely will compare well with my usual mix 73 binocs for 0-30MHz galvanic isolation chokes.
^Mutiple posts merged.
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Changed out the hybrid transformer on the 31' vertical for a LDG 1:1 balun. The RG-11 feedline was rerouted and dramatically shortened.
Once again put a KD9SV common-mode choke near the house entrance.
An eBay "SDR protector" and the earlier mentioned TDK N30/T65 series choke are close to the Airspy HF+D, though I need to get around to swapping that choke for a galvanically isolated one to better cleanup LW and lower.
Now to eventually get around to deploying more than the current four on-ground radials. I am thinking about acquiring some long ribbon cables. 10m 10-wire cables can be found for like a dollar or two shipped via welcome deals at AliExpress. Seems like they would be somewhat easier to deploy in greater quantities. Attach then separate as ya' go. On the downside I suppose they might even be CCS wire, but I have used CCS speaker wire for on-ground radials in the past with okay results if sealing the connectors and ends from water intrusion.