Messages

796

North American Shortwave Pirate / Re: Black Flag Radio 6952 USB 2304 UTC 26 Sep 2021

« on: September 26, 2021, 2351 UTC »

Peaking S7 and SINPO 45454 at 2351z via the 31' vertical. Occasional light static crashing. Audio is a little compressed at times, but plenty listenable and overall still an easy copy.

Thanks for the broadcast and shout-out! :)

797

Shortwave Broadcast / Re: Your favorite shortwave broadcasts

« on: September 22, 2021, 1004 UTC »

Radio Rebelde, XEPPM-OC, WTWW, and Voice of Greece are my usuals for background music. Listening to music on XEPPM-OC on 6185 right now.

I have slacked off on Radio Havana in recent years, but I occasionally still enjoy some of the cultural and music programming. Pretty much the same with CRI, NHK, Radio Romania, etc.

798

Equipment / Re: LOG Not Performing Well

« on: September 16, 2021, 1212 UTC »

Your 60' loop has extremely low impedance at longwave and lower. Complex impedance aside, simple impedance likely is a few ohms at best.

You have a low impedance antenna, around 50-75-ohn coax, and probably around 50-ohm receiver. Your antenna is a significant mismatch, even to the point of almost appearing to your receiver as being *short* at low frequencies, thus incurring even greater losses for an already negative again LoG.

A 9:1 lowers the impedance even further by a ratio of.... well, 9 to 1. ;) Turning it around to become a 1:9, you can use the transformer to up the impedance match between the antenna and feedline/receiver, thus improving the match and incurring less losses at low frequencies. Your Nooelec balun will not have the right connectors if turned around, but you can overcome that with a little soldering.

Alternatively, the mismatch is part of the reason I said to try connecting the loop straight to the coax. Having no impedance transformation should be better than having a 9:1 transformation, at least at very low frequencies for your small LoG.

799

Amateur Radio / Re: Age of ham radio operators

« on: September 15, 2021, 0117 UTC »

CW does not work for me, which is a primary reason I never bothered getting licensed when younger. It is not simply learning the code. It is not patience. Forget it even being another language, as you might as well be shouting absolute gibberish at me. I just do not process it for whatever reason.

Looking forward, I suspect we might see two or even just one FCC amateur license class at some point.

800

Equipment / Re: LOG Not Performing Well

« on: September 14, 2021, 1810 UTC »

My 148' LoG can receive longwave BCB stations with no preamp when propagation cooperates, but those stations are using extremely high-wattage transmitters. I am not really into NDB monitoring, but I have noted some when spinning the VFO down there.

An "ideal" start for a fractional loop is probably around 15% of the the desired wavelength.

Let us look at the bottom of the AM BCB band for an idea:

530KHz = ~565m * 0.15 = 277.5m

So around a 900ft loop there. Proximity to ground will lower resonance by a few percent, but we are dealing with such large loop sizes now, it is a "whatever" IMO.

If we disregard noise, ~1000ft+ would be a good start for an "ideal" low-frequency BoG. However, low frequencies are typically swamped by atmospheric noise, so you simply need an antenna with enough capture area for the receiver to detect the desired signal. Above that is basically just added gain, and it is about SNR instead of absolute gain.

TLDR? For longwave and lower, deploy the largest LoG you can.

----------------

About common-mode noise, let us start with a very basic test assuming we are talking about a typical residential deployment. Tune your desired frequency with an antenna in the house, even if it is just a few feet of wire. Now hookup your outside antenna. Regardless of the signal level, do you hear the *same* noise? If so, you might have common-mode noise. If common mode is suspected, to further evaluate if the noise is being picked up by the antenna or the feedline, you would need to evaluate if the same noise is present at your antenna location. For example, by using a portable receiver.

----------------

Your Nooelec balun still is acting as a impedance transformer, though it is so small I am not sure what effective impedance transformation it is doing at such low frequencies. Hmmm. Considering a 60' loop is going to resemble almost an electrical short at longwave and lower, an 9:1 might actually work better if you turned it around at the antenna feedpoint. YMMV.

801

Equipment / Re: LOG Not Performing Well

« on: September 12, 2021, 1720 UTC »

Ground conductivity extremes can influence a LoG by like 20dB+, but your southern mountain soil is likely average to maybe slightly below average, so you should be able to disregard that issue.

https://forums.qrz.com/index.php?threads/loop-on-ground-antenna.622669/page-15#post-5742886
http://www.w8ji.com/receiving.htm

Your current LoG is basically *way down* on gain. Like others have noted, go larger for both the conductor and the loop circumference, though even then you might still need a preamp as frequency increases. Just part of dealing with a typical LoG antenna.

Also I would not worry too much about ordering or building an impedance transformer for the loop feedpoint for now. Start with a basic RF choke if you have *actual* common-mode noise. Get the LoG far enough away from local RFI sources, and you might need nothing but the coax between the loop and receiver.

http://www.karinya.net/g3txq/chokes/

802

Amateur Radio / Re: Age of ham radio operators

« on: September 11, 2021, 0440 UTC »

Licensed or actually active? ;) I suspect active ops skew heavily to your listed 46+ demographic.

I am not licensed. When I *rarely* do talk on air, it is usually 27.385LSB or similar.

803

Equipment / Re: Interesting Chinesium SI4732 Shortwave/Air/FM

« on: September 11, 2021, 0307 UTC »

I suspect it was intended to mean HF aeronautical, then again, most of the bulk "Chinesium" electronics resellers often do not have much a clue about the tech specs of what they are selling anyway.

Edit: Oh yeah, as of last check, my ATS-20 still is working. I think it is on V3.0.7c firmware, which is a revision behind, so I need to get around to flashing an update.

804

North American Shortwave Pirate / Re: Radio Genix 6950 USB 1419 UTC 10 Sep 2021

« on: September 10, 2021, 2020 UTC »

Modulation in the noise floor via my 148' LoG with preamp.

805

Amateur Radio / Re: Ops are talking on 160M already.

« on: September 10, 2021, 2016 UTC »

They call it 'The Gentleman's band', but I see it more as a band of smugness. Just my take.

Also, if talking AM on 160 or 75, remember you surely need to be using a decommissioned BCB transmitter weighing hundreds of pounds (or more) with a Gates, RCA, etc. logo. Bonus points if you are modulating 10KHz+ wide.

806

Amateur Radio / Re: Ops are talking on 160M already.

« on: September 10, 2021, 2006 UTC »

This time of year in Florida, I'm not even able to turn on my radio when I get home due to lightning sometimes for days at a time.

I would not suggest using your FT-950 with lightning in the area, but you still could use your SDR or portable at least for listening with your outdoor antenna(s). Build a simple ESD protection circuit with a couple of diodes, LED, etc. for extra peace of mind, or order pretty much the same thing from eBay listed as a SDR guard for around $15 to $20 shipped. I have a couple of the eBay units on my primary receivers.

Going a step further, you also could put a cheap $6 eBay LNA preamp in line. If ESD cooks it, you are out a few dollars for a replacement. It probably is not ideal for SNR, but if the alternative is not listening to HF radio at all for days at a time….

807

Equipment / Re: LOG Not Performing Well

« on: September 10, 2021, 1850 UTC »

Size was not too critical to my design, but I was shooting for a loop circumference somewhat under the 40m band. It ended up being about 148' after laid out and deployed.

Here is the basic design of my LoG:

https://www.hfunderground.com/board/index.php/topic,29940.msg114696.html#msg114696

About a transformer, try it without one. Just connect the loop straight to your coax and see what happens.

Another consideration is knowing a LoG is mostly a skywave antenna. If you model a LoG, its primary lobe is vertically upwards, thus it can be a good solution for receiving via NVIS and high-angle signals. That is part of the reason your LoG might fair poorly during the day but much better at night, especially at low HF and below. Typically I use my LoG more as a regional antenna these days.

Yet another consideration is your soil conductivity. The characteristics of an antenna on the ground can vary considerably depending upon the actual ground. I have sandy soil with poor conductivity, which explains why my LoG performs about the same as when it was deployed years ago despite it now being mostly covered in shifting sand, leaves, etc.

808

Amateur Radio / Re: Ops are talking on 160M already.

« on: September 08, 2021, 2247 UTC »

There is often a nighttime ragchew or two on 160m here, even during the tropical weather season. Mostly just ops around the state, though, so not exactly weak signal DX work.

809

Part 15 AM and FM Station Operation / Re: Part #15 TX'ing on the 11M Int BC Band?

« on: September 08, 2021, 2241 UTC »

Beyond part 15, I have inquired before about possible pirate radio activity on or near the 11m broadcast band. It is a good daytime band for at least part of the year, requires a relatively small antenna, and it is mostly vacant except for the already noted 11m CB freebanders.

810

Equipment / Re: LOG Not Performing Well

« on: September 08, 2021, 2233 UTC »

You are using a beverage transformer designed for 400-500 ohms terminating resistance. You LoG is a fractional wavelength antenna below the 20m band, or perhaps more around the 30m band due to resonance changing as approaching the lossy ground. Either way, your transformer is taking an already low-impedance antenna and lowering the ohms even further as frequency decreases, thus increasing mismatch and losses.

Start with removing the transformer IMO. Wind a 1:1 or whatever if needing common mode current isolation from the feedline, though as for balancing the LoG itself, the antenna already should be rather balanced regarding differential currents.

I only have a few snap-on ferrites on the coaxial feedline at the the feedoint my 148' LoG. I do have a decent RF choke back at the receiver end, but it is not really needed for my particular deployment, either. YMMV.