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Author Topic: Best MWDX antenna?  (Read 6090 times)

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Re: Best MWDX antenna?
« Reply #45 on: April 21, 2021, 0236 UTC »
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/

Offline RobRich

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Re: Best MWDX antenna?
« Reply #46 on: April 21, 2021, 2119 UTC »
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
Tampa, FL USA | US Map Grid EL88
Airspy HF+ Discovery | Kenwood R-600 + R-2000 | 2x RTL-SDR V3 + NE602 | Si-Tex 200 | Soft66LC4 | Yaesu FRG-7
148' "Shielded" Loop-on-Ground | 18' End-Fed Vertical | 9' + 31' Verticals | 2x PA0NHC MiniWhips

Offline alpard

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Re: Best MWDX antenna?
« Reply #47 on: April 21, 2021, 2144 UTC »
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.
« Last Edit: April 21, 2021, 2235 UTC by alpard »

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Re: Best MWDX antenna?
« Reply #48 on: April 22, 2021, 0026 UTC »
Well, Mr. Google to the rescue. Kiwa filters still appear to be very much active, at least their web site 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/

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.


Offline pinto vortando

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Re: Best MWDX antenna?
« Reply #49 on: April 22, 2021, 0058 UTC »
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.
Das Radiobunker somewhere in Michigan

Offline pinto vortando

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Re: Best MWDX antenna?
« Reply #50 on: April 22, 2021, 0110 UTC »
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.
« Last Edit: April 22, 2021, 0111 UTC by pinto vortando »
Das Radiobunker somewhere in Michigan

Offline alpard

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Re: Best MWDX antenna?
« Reply #51 on: April 22, 2021, 1239 UTC »
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.

Offline alpard

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Re: Best MWDX antenna?
« Reply #52 on: April 22, 2021, 1416 UTC »
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.



Looks simple but tidy and well made.
Thanks for the tips for building one. Great advice.

Offline ThaDood

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Re: Best MWDX antenna?
« Reply #53 on: April 22, 2021, 2003 UTC »
When asked about White Supremacy, I do not believe in it, since most white people that I know are very much mediocre. Therefore, I believe in White Mediocracy.

Offline RobRich

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Re: Best MWDX antenna?
« Reply #54 on: April 22, 2021, 2040 UTC »
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
« Last Edit: April 22, 2021, 2048 UTC by RobRich »
Tampa, FL USA | US Map Grid EL88
Airspy HF+ Discovery | Kenwood R-600 + R-2000 | 2x RTL-SDR V3 + NE602 | Si-Tex 200 | Soft66LC4 | Yaesu FRG-7
148' "Shielded" Loop-on-Ground | 18' End-Fed Vertical | 9' + 31' Verticals | 2x PA0NHC MiniWhips

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Re: Best MWDX antenna?
« Reply #55 on: April 23, 2021, 0246 UTC »
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 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.

Offline alpard

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Re: Best MWDX antenna?
« Reply #56 on: April 23, 2021, 1643 UTC »
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.
« Last Edit: April 23, 2021, 1751 UTC by alpard »

Offline alpard

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Re: Best MWDX antenna?
« Reply #57 on: April 23, 2021, 2013 UTC »
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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Re: Best MWDX antenna?
« Reply #58 on: April 27, 2021, 0157 UTC »
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.

Offline alpard

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Re: Best MWDX antenna?
« Reply #59 on: April 27, 2021, 0836 UTC »
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.

« Last Edit: April 27, 2021, 0923 UTC by alpard »