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Messages - RobRich

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91
Software / Re: what software do pirates use to transmit?
« on: March 10, 2024, 2111 UTC »
Whatever media player. Another vote for foobar2000. :)

Ideally you would want to keep the output level at least somewhat normalized, such as with AGC, compression, clipping, etc.

Broadcast is a decent place to start if using a VST plugin host with foobar2000.

https://www.foobar2000.org/components/view/foo_dsp_vst3
https://plugins4free.com/plugin/548/

Stepping up to more commercial Stereo Tool is a popular software DSP for broadcasting, streaming, and even local listening. The free version is a good place to start and tends to suffice for many users.

https://www.thimeo.com/stereo-tool/
https://www.thimeo.com/documentation/

Stereo Tool could be used a Winamp DSP plugin in foobar2000 or a standalone app with a virtual audio cable interface like VB-CABLE or  VAC if desired.

https://wiki.hydrogenaud.io/index.php?title=Foobar2000:Components/Winamp_DSP_Bridge_(foo_dsp_winamp)
https://vb-audio.com/Cable/
https://vac.muzychenko.net/en/

92
Anthem at 2011z then off air. SIO 333. ~S6 via KiwiSDR 2 and 31' vertical.

Thanks for the broadcast! :)

93
10/11 meters / Re: WWV's 25MHz signal?
« on: March 05, 2024, 1903 UTC »
25000 WWV is usually present during daytime hours here. Currently ~S9 at 1902z via Airspy HF+D and 31' vertical. Nearly 60dB SNR.

94
10/11 meters / 11m Band Activity 05 MAR 2024
« on: March 05, 2024, 1824 UTC »
11m DX is hopping this afternoon here. Europe, Mexico, Hawaii, etc. Even UK NFM CB. Airspy HF+D and 31' vertical.

1827z - 27.66125nfm - Music and occasional voice comms


(click to open)

95
Orders being accepted now for the second production run.

https://forum.kiwisdr.com/index.php?p=/discussion/comment/17961/#Comment_17961

https://kiwisdr.nz/collections/all

The devs are ordering parts for a third production run, too.



BTW, mine is working fine. :) Just not public, and it probably will not be until I get it off an USB switching power supply and decide on an antenna.

96
Equipment / Re: Best MWDX antenna?
« on: March 05, 2024, 1548 UTC »
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.


(click to enlarge)


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.


(click to enlarge)


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.


(click to enlarge)




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?).





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.


(click to enlarge)



(click to enlarge)[



(click to enlarge)



(click to enlarge)[/urlg



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 40C: 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.

97
Equipment / Re: Best MWDX antenna?
« on: March 03, 2024, 0612 UTC »
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.

98
Equipment / Re: Best MWDX antenna?
« on: February 25, 2024, 2042 UTC »
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.

99
Equipment / Re: Best MWDX antenna?
« on: February 24, 2024, 1648 UTC »
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.

100
Music at 0459z. Off at 0500z? SIO 332. Airspy HF+D and 31' vertical. AM sync tuning. Decent carrier.

Thanks for the broadcast! :)

101
Equipment / Re: Sky loop...height vs diameter
« on: February 24, 2024, 0456 UTC »
Similar results with my current 148' LoG that has an 1:1 balun at the feedpoint. I could imagine low LF and especially VLF radiation resistance to be down into the low milliohms.

Interestingly my old 148' shielded LoG actually worked somehwat decently on longwave, though it was not using any balun or transformer at the feedpoint, so it might even have been common-mode on the feedline contributing to the low-frequency reception.

102
It seems to be a decent signal in recent weeks. Flex and I have logged it over on the SWBC section as well.

https://www.hfunderground.com/board/index.php/topic,125747.0.html
https://www.hfunderground.com/board/index.php/topic,125545.0.html

103
Received mine, but admittedly, it is still in the box. I might get around to initial testing over the weekend.

104
Equipment / Re: Sky loop...height vs diameter
« on: February 22, 2024, 0458 UTC »
Assuming a 300' loop, at low frequencies up to ~3-4MHz it will likely model as more of a blob shape with more "gain" (actually less loss) straight up than towards the horizon. It should be a decent NVIS antenna.

Around ~6-7MHz is going to shift the pattern more towards the horizon than straight up. Not exactly a big deal IMO, as NVIS tends to roll off above 7MHz, if even that most days, anyway.

As you go higher in frequencies the pattern towards starts breaking into multiple lobes, with the resulting gain and loses depending upon the distribution of those lobes.

Losses will increase as the loop approaches ground, especially as frequency drops. Works pretty much that way for most any horizontal antenna, be it a dipole, loop, etc. That said a low loop will likely have ground losses across pretty much the whole HF spectrum, thus the previous mention of "gain" in quotes.

Actually, lots of us have receiving loops placed directly on the ground. ;) Losses can be offset with a preamp if truly needed, though a preamp is often not a requirement at low frequencies, especially with large loop sizes. My 148' LoG typically suffices without a preamp from MW up to around mid-HF.

Summary? A large loop even at relatively low heights should suffice as a decent receiving antenna where losses at higher frequencies can be offset with a preamp if needed. Conversely, it not so much as a great transmitting antenna, though lots of people routinely work lots of contacts with horizontal antennas at low heights. YMMV.



Now as compared to an 80m dipole at 35'+ height? Ground losses still will be present at low frequencies, but that issue should improve around ~7MHz.

The dipole is still low enough to more favor NVIS at lower-HF frequencies. As frequency increases above ~7MHz the dipole should start having more gain at angles more towards the horizon than straight up.

As to pattern the dipole is going to become more bidirectional as frequencies increase, though opting for an inverted V deployment will somewhat improve an omnidirectional pattern at the sacrifice of some broadside directivity.

The dipole will start breaking into more lobes as frequency increases, too.



Personal thoughts? Given the feedpoint height differences present, I would likely favor the dipole with a feedpoint at 35'+..... though perhaps a different type of dipole with symmetrical balandce. An 90'+ doublet center fed at 35'+ as an inverted V should make for a decent HF antenna, especially from 80m to mid-HF. Coaxial feedline would suffice for receiving; just ignore the mismatches. If transmitting is desired, feeding a doublet with ladder line and using a tuner would be the (much!) better approach.

https://ftp.unpad.ac.id/orari/library/library-sw-hw/amateur-radio/ant/docs/Introducing%20the%20All-Band%20Doublet.htm

105
Equipment / Re: LoG receive antenna, Loop on Ground!
« on: February 20, 2024, 1132 UTC »
It is a magnetic loop design. Note the "Let's look at the ideal coupling method:" here:

https://www.w8ji.com/magnetic_receiving_loops.htm

An often-cited claim for a shielded loop is the design somehow blocking electrical fields to optimize reception of magnetic fields. Outside of maybe some slight near-field effects, a shielded loop does not really shield much of anything.

Instead the shielded design is more or less to help balance loop symmetry to potentially equalize differential currents and limit common-mode currents. Therein is why a "shielded" loop might improve reception if CMC is present on the feedline. If not, then there is not much, if any difference versus just a simple wire loop.

These days, I might would make some changes. I probably would use a mix 73 binocular ferrite with a 1:1 winding ratio at the feedpoint. Using 4 turns towards the loop and 4 turns towards the feedline should suffice in my experience. The result is an isolation transformer. You probably could just float the loop shield in such a config.



BTW, another often-cited LoG design consideration is software modelling might suggest a couple or so dB in directionality if feeding the loop at a corner instead of a midpoint along a side. Being realistic I kind of doubt any noticeable real-world difference.



Another popular alternative for a coaxial loop would be the NCPL design, which is basically a mobius loop. It might help a little with low-frequency performance for a typical-sized loop-on-ground antenna.

https://swling.com/blog/2020/04/diy-how-to-build-a-noise-cancelling-passive-loop-ncpl-antenna/
https://www.hamradio.me/antennas/airspy-youloop-lf-mf-hf-mobius-receive-antenna.html



All the above said, unless you have the coax available for experimenting, I would suggest first trying a simple wire loop-on-ground. 60' to 150' of whatever wire should suffice for MW to mid-HF. You might need a preamp towards upper-HF. Use an 1:1 balun or an isolation transformer at the feepoint, plus perhaps similar back near the receiver.

Case in point, my old 148' "shielded" LoG ended up buried under leaves, pine needles, and shifting soil/sand. A typical LoG is already well into negative dBs, and going underground can make the losses even worse. Mine was old enough to not bother with it anymore, so I eventually just deployed another LoG at a different spot. My current LoG is 148' of copper pet fence boundary wire with a LDG 1:1 balun at the feedpoint and a mix 73 isolation transformer near the receiver. The simple wire LoG seems to suffice for my purposes at the moment. YMMV of course.

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