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Topics - Charlie_Dont_Surf

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A friend who lives in Europe asked me to design a small transmitter. He has a supply of FT-243 crystals from "the before time" and wants to use them on a small transmitter. I hadn't done much with crystals in years but after doing a bit of looking around, I started looking at the venerable and often used LULU design.

As I looked, there were a number of things that bothered me about them and I could see that there was quite a bit of “low-hanging fruit” that could be easily “picked off the tree” (improved) without a huge effort. In the end, I decided to redo and modernize the LULU for him, making it an updated LULU, i.e., the “U-LULU”. I have added a commercially-available Class-D audio amplifier to make a complete AM transmitter with approximately 20 Watts carrier power output (80 W PEP) in the 48-meter band. This is better than the original LULUs, where output is reported to be in the 10-to-15-Watt range. I decided to publish this design to make it accessible to others.
 
I regard this as an entry-level transmitter, suitable for those with less building and electronics experience. For the SMD haters, I have purposely used a through-hole TO-220 transistor and larger SMD components. Most capacitors are at least Imperial 1206/1210 [Metric 3212/3225] though there are some 0805 [Metric 2012] components.

Complete write-up is here: https://app.box.com/v/ty24asdfjAEF00

Gerber files zip archive is here: https://wetransfer.com/downloads/0415f9221a49b764d95fb207e143c59e20211205050846/d5a62f

BOM is here: https://wetransfer.com/downloads/9a9d186b74de847f01f336f0f2ee4b0a20211205050536/9d12ab










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Caught the sign on (just after the Lincolnshire Poacher IS) just now. Good signal on the KFS SDR (Half Moon Bay, CA).
The heterodyne comes from beating against Coastal Rock Radio (presumed ID).

https://voca.ro/1cKDqAuvaIlr

0152 - I had some things to do but got back in my office and checked. Signal has faded down significantly. It is just barely above the noise now. I could just detect the female voice ID at this time.

3
Shortwave Pirate / Pandemic Radio 6925.9 AM 0128 UTC 16 November 2021
« on: November 16, 2021, 0130 UTC »
Clear ID 0128 UTC after the end of "House of the Rising Sun". Getting QRM from the UNID +80 Hz up the band. Listening on a Nevada SDR while I do work in my office.
0137 - "Pandemic Radio transmitter number 2 online....Shelter in place..... Prepare for 'The Great Reset'". Into David Bowie.
0143 - Dire Straights.

4
Shortwave Pirate / Radio Pushka 6920 AM 0025 UTC 16 November 2021
« on: November 16, 2021, 0026 UTC »
SIO 444 on the KPH webSDR in California, SIO 232 on W0AY in Montana.
Slavic music.

5
Shortwave Pirate / Radio Pushka 6920 AM 0200 14 November 2021
« on: November 14, 2021, 0227 UTC »
S9+10 on the KPH-HF KiwiSDR in Point Reyes, CA. Excellent copy.

6
Shortwave Pirate / Radio Pushka 6920 AM 0100 UTC 11 November 2021
« on: November 11, 2021, 0111 UTC »
This is a rare moment when there are two AM pirates audible on the West Coast simultaneously!

SIO 333 on Norcal SDRs.
QRM from a peskie playing music on 6919 LSB. (Also heard last evening too.)

0122 - ID , into funk (BTW - who are "Chaz and Stacis" (?) and why do the "hate this station"?)
Continuing with Slavic rock/pop.
0154 - either went into a deep fade or TX off.


7
Shortwave Pirate / Radio Pushka 6920 AM 0045 UTC 03 November 2021
« on: November 03, 2021, 0052 UTC »
ID at 0054. Fair-to-good reception in California. SINPO 33333 once you filter out the peskie interference on ~6923-6925.
Also noted in TeXas but weaker. Fair-to-Good on W0AY SDR in Montana. Very weak on SDRs in Alberta and British Columbia.

8
Utility / My First ALE 2G Logs
« on: October 25, 2021, 2124 UTC »
Running on a Kiwi SDR in Germany this afternoon and I let it run a scan on the UK DHFCS frequencies:

[2021-10-25 20:31:29 5808.00] [Sounding THIS WAS] [From: XSS] [His BER: 0]
[2021-10-25 20:31:47 8182.00] [Sounding THIS WAS] [From: XSS] [His BER: 11]
[2021-10-25 20:39:08 6845.00] [Sounding THIS WAS] [From: XSS] [His BER: 17]
[2021-10-25 20:39:54 6251.00] [Sounding THIS WAS] [From: XSS] [His BER: 0]
[2021-10-25 20:40:02 8161.00] [Sounding THIS WAS] [From: XSS] [His BER: 10]
[2021-10-25 20:40:09 8161.00] [Sounding THIS WAS] [From: XSS] [His BER: 2]
[2021-10-25 20:40:46 7860.00] [Sounding THIS WAS] [From: XSS] [His BER: 15]
[2021-10-25 20:45:01 4047.50] [Sounding THIS WAS] [From: XSS] [His BER: 3]
[2021-10-25 20:56:11 4239.50] [Sounding THIS WAS] [From: XSS] [His BER: 4]
[2021-10-25 21:01:50 5808.00] [Sounding THIS WAS] [From: XSS] [His BER: 14]
[2021-10-25 21:02:00 8182.00] [Sounding THIS WAS] [From: XSS] [His BER: 23]
[2021-10-25 21:02:16 6706.00] [Sounding THIS WAS] [From: XSS] [His BER: 2]
[2021-10-25 21:09:22 6845.00] [Sounding THIS WAS] [From: XSS] [His BER: 0]
[2021-10-25 21:09:59 6251.00] [Sounding THIS WAS] [From: XSS] [His BER: 10]
[2021-10-25 21:10:21 2784.00] [Sounding THIS WAS] [From: XSS] [His BER: 5]
[2021-10-25 21:12:20 3640.00] [Sounding THIS WAS] [From: XSS] [His BER: 3]
[2021-10-25 21:15:07 4047.50] [Sounding THIS WAS] [From: XSS] [His BER: 0]


I'm pretty new to ALE and I don't do a lot of data SWLing. I know what BER is but I don't know what THIS WAS is.

Also, now I know what ALE 2G sounds like. It's that chattery, bubble machine type of transmission (as heard in SSB) in 1-3 second duration bursts that I hear quite a lot these days.

9
Shortwave Pirate / Radio Pushka 6920 AM 0235 UTC 24 October 2021
« on: October 24, 2021, 0249 UTC »
Difficult copy with a lot of fading. Mostly not audible at home. Best on California SDRs (so far). Some bass distortion.

0237 - 3 Doors Down, Kryptonite
0241 - Pearl Jam, Even Flow
0241 - Clear ID on fade up
0242 - Lenny Kravitz
~0254 - Clear ID
0257 - Metallica (I think)
0315 - ID
0329 - mostly faded out everywhere but I can see a trace of carrier on some SDRs.

I'm done with this. Good night.

10
Shortwave Pirate / Radio Pushka 6885 AM 0210 UTC 29 August 2021
« on: August 29, 2021, 0240 UTC »
Noted at home and on several SDRs in California, Arizona and the western US. Generally too weak to get much out of it though.

0226 - Pearl Jam
Rock music but hard to ID it all by ear.
0310 - ID, thanks for the help DXace1. In Cyrillic, Радио пушка, meaning, "Radio Gun".
0320 - Pink Floyd. I switched to the KFS SDR.
0333 - Def Leppard, "Pour Some Sugar on Me"
0343 - Radiohead - "Creep". STANAG is starting to be a problem.
0349 - Clear ID between songs. Pro-sounding announcements.

12
Shortwave Pirate / Outhouse Radio 6950 USB 0445 UTC 3 Jan 2021
« on: January 03, 2021, 0458 UTC »
ID at 0457 with fun blues music. Listening via SDR in Pennsylvania. Good copy but maybe just turn down the music a smidge - sounds like you are slightly overdriving it.
0502 - better now. Thanks!
0547 - Off. Thanks for the tunes.

13
Shortwave Pirate / Damn Skippy 4020 USB 0543 UTC 1 Jan 2021
« on: January 01, 2021, 0544 UTC »
I hear music, definitely electric guitars. Perhaps some death metal.
Tough copy out west. I am getting better reception on N1NTE's SDR but still poor.
0556 - SSTV
0613 - off after SSTV

14
The RF Workbench / TI GaN ICs
« on: December 18, 2020, 2214 UTC »
Texas Instruments has been introducing some nice integrated products composed a GaN transistor or transistors with integrated drive and protection circuitry (over current, over temperature, etc.)

These look pretty sweet for HF transmitter applications where size matters (we all know that size matters. :D ), though I have not yet tried to make one yet.

https://www.ti.com/power-management/gallium-nitride/products.html

Since they are integrated products in ~8 mm x ~8 mm QFN packages, you may have to pay more attention to power dissipation than you might with a TO-220 or TO-247. You may consider putting a heatsink on bottom side of the PCB. It will also force you to pay (yet) more attention to efficiency. On the other hand, if you aren't careful enough with the above, the integrated over temperature protection will notify you of that and save you from vaporizing your $12 chip that you just spent a bunch of time soldering down.

The other thing to note is that the exposed paddle on the bottom of the part is the main pathway to remove heat. The exposed paddle must be soldered to the PCB and you aren't going to do that with your 30-Watt soldering pencil. You will need SMT techniques: solder paste, a pre-heater for the bottom of the PCB and then do a sort of manual solder reflow with a hot air blower/pencil (unless you have access to a reflow oven).

15
The RF Workbench / Nexperia GaN FETs
« on: December 18, 2020, 2145 UTC »
I noted earlier in the year that Nexperia (the discrete arm of NXP Semiconductors) started offering GaN FETs but they seemed somewhat familiar and a couple weeks ago I put two and two together.

https://www.nexperia.com/products/gan-fets/

The GAN063-650WSA and GAN041-650WSB appear to be the same as the Transphorm TP65H050WS and TP65H035G4WS.

https://www.transphormusa.com/en/products/

Since Transphorm had their versions out earlier it is possible that Nexperia is re-branding Transphorm's stuff (that is, buying them under license, having them marked as Nexperia and selling them as Nexperia products). This happens a lot in the electronics industry now. On the other hand, Transphorm certainly does not have their own fab (too small) and they may have been buying wafers from NXP the whole time.

In any case, regardless of whom you buy them from, these are nice transistors for your transmitter project.

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