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Messages - Charlie_Dont_Surf

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1
Amateur Radio / Re: UNID FT8 6925 USB 0310 UTC 11 MAR 2024
« on: March 24, 2024, 0827 UTC »
If you are using some sort of LNA/pre-amp before all three receivers, then it is possible that you were hearing a mixing product/spur being generated in the LNA. However, if you aren't using an an LNA, then the fact that three receivers (all with three different dynamic ranges and input intercept points and at least two different receiver architectures, etc.) all heard it makes me think something else was going on.

Another thing to note, the thermometer below is red for a reason. It indicates that you had your audio cranked WAY up. Bad things tend to happen when you do that in WSJT-X. I find that I start to lose decodes and weird artifacts appear (which is exactly what we are talking about) if the receive audio is turned up enough that it averages 70 on that thermometer scale. I don't want to think about what 90+ means. Try to keep it between 40-60 on average and in the green.



I did see/hear some CW with an actual DX ham callsign briefly in roughly the 6930-6950 area about a month ago. I checked it on an SDR and it was there too. I assumed something was wrong with the op's TX because I only heard one side of the conversation. I went about my business and it disappeared after checking back an hour later. I forgot to write down the exact details. I think the op was Greek and I vaugely remember this happening during a contest weekend.

2
SUISSE: la station pirate Charleston Radio International a été fermée par les autorités helvétiques, le 28 février 2024 après-midi.  Cette station diffusait quotidiennement sur 5140 khz avec une puissance de 1 kw et était reçue dans toute l’Europe. Sa particularité était de diffuser de la musique des années 20 et 30, à l’occasion des 100 ans de la radio. Elle se faisait passer pour une station allemande et indiquait Berlin, en réalité son émetteur était situé au sud de la Suisse.
Harry Richman, son propriétaire a reçu la visite de trois agents qui ont pris des photos de l’émetteur et de l’antenne et ont emporté l’émetteur. Hardy sera certainement condamné à payer une amende dont il ignore encore le montant. Une mesure de clémence est plus que probable, car la Loi fédérale sur la radio et la télévision (LRTV) du 21 juin 1991 prévoit, à l’article 70, que "Sera puni d'une amende de 50 000 francs au plus celui qui aura rediffusé des programmes sans concession".
Alors Harry a dit que c'était maintenant de l'histoire ancienne et remercie tous ses auditeurs d'avoir écouté et publié au fil des années.  Il espère que vous vous souviendrez de moi avec tendresse.

Your translation completely missed the part I put in bold above. That portion of the sentence means "will be punished by a fine of 50,000 francs or more" so the complete sentence in translation would be:
Quote
"A measure of leniency is more than likely, because the Federal Law on Radio and Television (LRTV) of June 21, 1991 states in article 70 that, '(there) will be a fine of 50,000 francs or more for those that rebroadcast* programs without concession'".

So apparently this writer thinks that Harry will get a reduced fine because he cooperated in some manner.
50 000 CHF = $55,700 US = 51 400 EUR = 44 186 GBP at the moment. Ouch.

*French often uses the term "rebroadcast" when in English you would use "broadcast".


3
Not going to argue over a few hz.  :P



I got the frequency for the thread title from a GPS-locked kiwi SDR. (I didn't use the readout on my portable, which didn't quite agree). I then checked that kiwi against another GPS-locked kiwi and the two kiwis were within 1 Hz, which is expected. You might want to check your RX against CHU.

4
Just saw them go from DSB-AM to USB-AM to LSB-AM then back to DSB-AM

Yeah, I noticed this a few times too. I thought there might be some sort of weird selective fading or cancellation of one sideband going on in the ionosphere so I looked at other SDRs but saw the same thing happening there too, so it must have been coming from the transmitter.

Anyway, this just means that (I assume) they have independent control of the individual sidebands, so the transmitted signal is a summation of a carrier + LSB + USB. Which can be handy to have, I suppose. Unless you have a spectrum display you would never know by just by listening to the audio.

5
Off the air at 0301 UTC.

6
Caught the ID at 0257 on east coast SDR then carrier immediately off.  :-\

7
0238 - Obliterated for about 1 minute or so by digital interference. Otherwise SINPO 34343 / S6 on peaks when there isn't the interference. Listening while "glamping" near the beach in SoCal on my portable with a wire out the window.
0243 - Digital interference for 45 seconds.
0254 - Appears to be off the air when I checked back.

8
Changed freqs a couple times at start up. Currently on 6963.67 (approximately).
Listening on and off near the ocean in CA on a portable and a long wire. SINPO 33232 / S5 on peaks with a fair amount of flutter tonight. (The same thing was happening to Solar Federation Radio.)

0311 - Computer-generated male and female voices. Perhaps reading the email address in English and German.
0315 - Carrier off immediately after completion of national-anthem-type of song.

9
EDM. Best reception I have found so far is in Montana but still looking.

0250 - Appears to be off.

10
SINPO 44344 / S6 on peaks from the Montana transmitter. Listening on my portable with a wire antenna while camping (more like "glamping") at the beach in Southern California . (Montana isn't the "west coast" though.  :D )
If I go back to listening on a New England SDR, I can sometimes hear a little bit of polar flutter now.
Pretty cool that you have the ability to transmit from two different locations.

0137 - The Rolling Stones, "Honky Tonk Woman"
0144 - AC/DC, "Back in Black"
0146 - Aerosmith, "Walk This Way"

0158 - I tuned away for a bit and came back and now hear a lot of polar flutter out here. I guess you switched to the "east coast", huh?
0158 - Led Zeppelin, "Communications Breakdown"
0200 - Led Zeppelin
0221 - Inaudible direct. Only on east coast SDRs.
0222 - "Audio test" "Attention all of the planets of The Solar Federation." (repeated 3x) "We have assumed control." (Taken from Rush's album 2112.)
0225 - Audio frequency sweep from ~200 to ~3200 Hz, then off.


11
Albert - Sounds very interesting and thank you for nudging this project along.

I'm very interested to see how you implemented the envelope feedback. I never thought to do something like that because - as far as I could tell - much of the distortion came from the Class-D amplifier. I assumed this because I was operating it at essentially max load on peaks, plus a DC load on top of it (which it was never really built for). The THD dramatically increases from ~10 W to ~100 W (max) output and I just assumed that short of implementing some sort of pre-distortion (which I really was not interested in delving into), that there was probably not much I could do about it, other than use a much bigger Class-D amplifier. Apparently I was wrong.

As for other the use of other transistors, there are a limited supply of TO-220-packaged transistors that could be used and of course it must be said that the TO-220 package is going the way of the dinosaur over the coming years. As far as I know the Nexperia PHP18NQ11T that I used in the U-LULU has not been put on NRND ("not recommended for new designs") or EOL ("end of life") status yet, the former being the precursor to the latter. The Infineon IPP530 is really good in this application too. The TO-220 version is now in EOL but they have a TO-252 version that will likely be available for quite some time. The Toshiba TK11S10N1L should work too, but it only comes in a TO-252.


I have already made the schematic and created the PCB layout for a follow-up that is similar to what you describe:
1) frequency source of either a) a selectable crystal oscillator (with a real crystal driver chip that is designed to work at HF) or b) an external oscillator input.*
2) selectable audio preamp circuit for those that want to use laptop computer, mobile phone or MP3 player as the audio source
3) RF filtering on the input of the preamp to keep the amount of RF injection hopefully low enough
3) continue to use a Class-E output, tuned for a lower Q than the U-LULU that should be able to deliver roughly equal power output from 6200-6300 KHz,
4) probably with an output somewhere between 30 to 40 Watts, better than U-LULU, largely due to being able to run the gate drive voltage much higher than 6 Volts.
5) PCB footprint currently equal to the Sure audio module I recommend for U-LULU so that the two PCBs can be stacked one on top of the other.

Well, I did eventually get the bare PCBs back from fab but I have had to devote a lot of time to activities other than radio in the past 6 months. As a result nothing has been done to test it out.

12
The RF Workbench / Re: Distance with 10W on A.M. (M.W.)
« on: March 21, 2024, 0702 UTC »
ON4UN's book on low-band DXing is a good reference for this since 160 meters is reasonably close to the top of the MW band.

Chapter 9 on vertical antennas shows the effect of bottom loading (with a coil), center-loading (again with a coil) and top-loading, along with the effects of a capacity hat. Bottom line: a vertical with a capacity hat is incrementally more efficient than a top or center-loaded vertical, both of which are incrementally more efficient than a bottom-loaded vertical.

Of course, if you aren't using a vertical (or near vertical) wire, a cap hat may not be possible and there may be other practical reasons for using some of the less efficient coil loading described. The horizontal portion of an inverted L is perhaps a little bit like a cap hat but that's not really why the inverted L works reasonably well, assuming it's long enough.

13
A seemingly important reception detail, but for some reason no one else in this thread bothered to mention it:

The op announced that he is going through some "life changes" and he has to move house. ("The chicken has to cross the road.") The end result is that he expects to be off the air for 6-8 weeks.

14
Is this CW or is it USB? Seems like it was CW, so the thread title should reflect that.

15
Someone playing various older popular music tunes. Best audible in New England. Frequent changes in modulation level and QRN made it difficult to tell if they were still transmitting at times.

0621 - The Guess Who, "These Eyes".
0633 - Assumed lost.


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