Messages

226

North American Shortwave Pirate / Re: Damn Skippy 6925 USB 0220 UTC 1 MAY 2023

« on: May 01, 2023, 0223 UTC »

0224 - Electronic music. I'm scared.
0226 - Straight into C&W, I think.
0233 - Back to the scary music with sirens on top of it.
0240 - Classical music: William Tell Overture, I think, with other sound effects mixed in.

SSTV. Not so good  :


0251 - SSTV, a little better but...



0302 - "Days of Hard Life"   OK, man. Just don't start telling us about Yahweh.
0318 - Someone jamming away on their guitar to Black Sabbath.



0343 - I gotta roll, CU later.

227

North American Shortwave Pirate / UNID 6950 AM 0205 UTC 01 May 2023

« on: May 01, 2023, 0208 UTC »

Carrier is there. Stronger in the west than the east. Modulated perhaps but if it is, it is weak. The frequency is clear otherwise.

0208 - Carrier off for a brief few seconds then on again. I can hear music now but weak modulation.
0210 - Carrier was on and off a few more times.
0214 - Perhaps best on Half Moon Bay, CA. Modulation is much better. Ambient trance music, stuff you might hear waiting for a call center operator.

Recording https://voca.ro/11qxuAm81wkB

0218 - Carrier off between songs. Resumed and continuing with the "call center music".
0221 - TX off

228

North American Shortwave Pirate / Re:Yeah Man Radio 6925 USB 2324 UTC - 30 April 2023

« on: April 30, 2023, 2328 UTC »

2327 - ID. Jazz show. Listening on an SDR in Ohio. SINPO 45344.

229

Utility / CFARS Net 6977 USB 2220 UTC 30 APR 2023

« on: April 30, 2023, 2233 UTC »

Canadian Forces Affiliate Radio System secondary voice net.

Net control CIW681 taking check ins from the "500-700 districts". I'm not sure where this corresponds to but one check in was at Bagotville, QC, possibly associated with the CF base there.

No voice traffic from anyone. Closed ("secured") the net at 2230 UTC. Heard on a US SDR in Ohio.

230

North American Shortwave Pirate / UNID 6950 USB 0304 UTC 30 Apr 2023

« on: April 30, 2023, 0305 UTC »

0304 -  Hearing some very confusing electronic music on the Northern Utah SDR.
0317 - Been moving toward more blues. Likely Outhouse/Dog House/Skippy/etc and he was on earlier.
0324 - Off or faded out.

231

North American Shortwave Pirate / Re: WDOG 6925 USB 0125 30 April 2023

« on: April 30, 2023, 0243 UTC »

0239 - Suddenly off during "Get a Grip On Yourself".

I think that this was a replay of this from Thursday evening: https://www.hfunderground.com/board/index.php/topic,113220.0.html

From MDK2's notes that evening. Note the exact same song order.

0152 "In the City" The Jam
0154 OM with English accent saying "I'm not trying to impress anyone but myself" into "Trash" New York Dolls
0156 "Chinese Rocks" Johnny Thunders & The Heartbreakers
0159 "Fall Out" The Police
0202 "(Get a) Grip (On Yourself)" The Stranglers

232

The RF Workbench / Re: Class D audio amps - protection circuits

« on: April 28, 2023, 0318 UTC »

Yes, familiar with it. In fact, I mentioned it over here: https://www.hfunderground.com/board/index.php/topic,89881.msg348346.html#msg348346

How do you know that it is "DC Detect Fault" and not simply the overcurrent protection turning on? Overcurrent is simply drawing too much current from the output(s). This could be that you have an inappropriate load (likely too low impedance) or you are just asking for too much output based upon the load that is attached. In the latter case, you just have to turn the gain down or reduce the input.

If we are talking about the same thing, I generally I observe it as momentary drop in audio; basically just asking for too much from the amp. This is most likely to happen when there is heavy bass content to the program material. Not many alternatives for immediate relief other than reduce the bass content, turn down the gain or reduce the input. Also, it is important to note that these transmitters do not look like a pure resistor to the Class-D amp output; they will look like a complex impedance, especially below some arbitrary audio frequency. The Class-D amp may be "happy" with the load that the transmitter looks like at 1 KHz but very "unhappy" with the (probably) different impedance at 50 Hertz, for example.

The reason why bass tones are more likely to cause a problem, is for one thing, bass tones are low frequency, which means longer period and thus the Class-D output is on for a comparatively longer period of time. The overcurrent protection is only going to be triggered when the output is on, so, if there is an impedance problem that would trigger an overcurrent fault, it's more likely to occur on bass than treble just by sheer probability.

Beyond that, I have noticed some interesting turn on characteristics. If I have an audio input present at turn on that is too strong, it can create some sort of fault condition that is difficult to clear without turning off the amp, lowering the input and trying again.

233

SDR - Software Defined Radio / Re: KiwiSDR future/replacement?

« on: April 20, 2023, 2322 UTC »

John, the developer of the Kiwi, posted on the Kiwi forum some time back that he was also ready to sunset the project as he was pursuing other projects.

Which is curious because he keeps cranking out software revisions. Of course, hardware revisions have a longer timeline than software revisions.

The software the Kiwi user interface is based on, OpenWebRX https://www.openwebrx.de/ can be configured to work with a host of SDRs. It's not as feature packed.

You can say that again. For one thing, frequency resolution is lacking, IMO.

234

The RF Workbench / Re: Using LM7805 regulators for AF / RF amps?

« on: April 20, 2023, 2316 UTC »

You're modulating the DC (at an audio frequency) not RF.

You're confused and simultaneously confusing, as usual. Let's clarify.

Forgetting about which circuit we're talking about for a second, if you modulate the DC that is fed to a final amplifier, then you will amplitude modulate the signal. That's pretty fundamental. You can do this with a Class-A modulator, such as shown here or you can do it other ways, like a Class-D modulator and LPF. Either way, you're making the DC fed to the final amplifier wiggle up and down and that produces amplitude modulation on the RF at the "wiggle frequency".

In the case of the circuit from the OP, it only produces RF (without AF modulation, unless the RF already has modulation on it) riding on the DC. In the case of the second circuit, the one that I posted, it probably won't work very well at RF because it needs an inductor that the first circuit has.

235

The RF Workbench / Re: Using LM7805 regulators for AF / RF amps?

« on: April 20, 2023, 1805 UTC »

Yes. In that circuit, its upper frequency limit is likely defined first by the internal parasitics of the silicon die, the package and the physical PCB layout than so much the internal circuit design.

Also, you folks seeking a simple AM modulator for your <15 Watt transmitter can do as shown in the applications section of the L78xx data sheet:
https://www.alldatasheet.com/datasheet-pdf/pdf/22615/STMICROELECTRONICS/L7805.html

Page 22, figure 34, “Power AM Modulator”.

The concepts of the two are similar. The regulator does exactly what it is supposed to do: regulate a voltage. In the case of these circuits, ground voltage is being brought up and down by the AC or RF input. Therefore, the user is impressing that AC or RF voltage on the output of the regulator, which is forced to follow.

236

North American Shortwave Pirate / Re: Sycko Radio 6950 USB 0110 UTC 20 APR 2023

« on: April 20, 2023, 0145 UTC »

Look at the lightning map and weep. https://www.blitzortung.org/en/live_lightning_maps.php?map=30

Listening on an SDR in VT and it's noisy but we're doing it.

0233 - Waving a hand at you too. Pretty reasonable signal for only 40 Watts.
0309 - I switched to an SDR in Michigan. OMG, what an improvement. S9+20 on peaks, mostly well above the noise which is S9+10.
0354 - signal is fading out and the static is dominating. I need to go anyway. Good night.

237

North American Shortwave Pirate / Re: KAT re-broadcast via NAPRS 6935 AM 0040 UTC 19 APR 2023

« on: April 20, 2023, 0144 UTC »

I heard myself as Garfield Morris from an old KAT cassette that I sent out to people who reported my broadcast from my friend Pam's house on the rock river in Edgerton WI (25 miles SE of Madison) back in the 1990's,

I am unfamiliar with this concept of outing yourself 30 years after the fact.

238

North American Shortwave Pirate / Re: UNID 6935 AM 0130 UTC 18 APR 2023

« on: April 18, 2023, 0136 UTC »

This should be its own topic since it was a separate broadcast.

Off suddenly at 0133.

Was it really 6936? I had it on 6934.96 or so.

239

Software / Re: Black Cat ALE Vacuum Cleaner 0.3.0

« on: April 17, 2023, 2126 UTC »

You hear that "giant sucking sound?"

https://youtu.be/VRr60nmDyu4?t=89

240

The RF Workbench / Re: Common mode supression

« on: April 17, 2023, 2035 UTC »

My english still very bad, but i should tell here about my experiments.

Your English is good enough to write this, which is reasonably high. I can see that you paid attention in English class. 

Common mode noise i measure between PC case and grounding in 9 floor building via 10:1 voltage divider - almost 13 volts.
http://hoshinokoe.ru/files/0ARTICLES/common_mode/interf_pc_case.jpg

OK, understood, however, I don't think that this is completely unusual and don't take this as positive proof that you have "a lot of noise". Your photos of the SDR screen do indicate that there is quite a bit of 1-30 MHz noise but I would not say that the oscilloscope image is indicative of the SDR waterfall images. That is, one does not necessarily lead to the other.

A few things to note:
1) Oscilloscope probes that are not grounded will often pick up (receive) noise like this.
2) I believe that you have connected the oscilloscope probe to a AC to DC power inverter output (but without a ground connection?). Understand that this output should be a high impedance node for anything above ~10 KHz (because the parasitic L increases the output impedance at higher frequencies), making the DC cable a very nice antenna, so the oscilloscope (which also has a high impedance input) will pick up quite a bit of noise from everything in the general area.
3) I think that the oscilloscope may not be connected to the same AC mains outlet (220V outlet) as some of the other items on your desk. This can create a ground loop that can create enough noise to show up on an oscilloscope by virtue of the different ground voltages at frequencies greater than DC.
4)  The oscilloscope probe is ~30 cm from the computer screen and there are likely many power inverters within ~1 meter of the probe.

So, again, it looks ugly but I wouldn't make a lot of decisions about what to do about it based upon this measurement that you show.

I still not measure this long balun, but it seems t be its better then only miniature transformer.
Today i made a Austin tranformer for HF to measure its reactance for common mode.
http://hoshinokoe.ru/files/0ARTICLES/balun_for_SWL/Austin_trans_isolation.jpg
...
Now i use "long" balun with my personal sdrs and parallel with web-sdr on my personal webpage.

You may want to consider using two antennas (e.g., the 8m wire and the 30 m wire) and a variable phasing network to be able to rotate (change) the phase of the two wires relative to each other to attempt to partially cancel some of the noise by making it out of phase.