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I would like to close this topic. Replacing D27 and D28 solved the problem that the swr-power meter can now measure correctly. This is how output power monitoring works. I received the IRFZ24Ns I

I went a bit around the issue of heat conductors. I came to an interesting conclusion. I found a study material in Hungarian that deals with this topic. * Briefly about the thermal conductivity of

Speaking of thermal conductivity please see my message #103820. You might find it eye opening. Jack, N6LN

There is another failure mechanism to MOSFETs that is not being mentioned here, that of too low a gate to source voltage, this does result in thermal runaway. Whether that is part of the problem of

BTW since the question was brought up the idle receive current for the rig including the screen is about 0.8 amps. My linear supply is at 14.0V at idle and drops to 13.6V on 30W CW transmit on 80M.

This beryllium graph is shocking. I decided to replace the mica insulators with beryllium oxide insulators.The first graph I showed two days ago comparing the sBitx DE continuous CW 30 W key down for

Frank, are you looking at the same website that I’m looking at?hfsignals.com? Right on the front page it tells you the size of the box, which gives you information about the size of the printed

Evan and Mark:? I now have my ubitx v6 back with the original firmware and screen.? The old screen works well but the radio does not receive or transmit.? I tried the BFO calibration again with no

Nothing about the size of the PCB, sadly neither any close-up pictures of the PCB 73 de Frank PH2M

I forgot the solution I used for one SSB TRX (analog) was to make an opening in the rear for a finned heat sink.? IT had to fitted so the fins were outside the box for convection cooling.? Since it

Line the inner surface with copper foil or conductive paint. I've done that with wood cases many times to achieve aesthetic results and still have the needed shielding.? The bare unfinished wood

Back last year I did a lot of PA related work and concluded it was a mess and dumped it (completely removed) for a PA to get between 5-8W.? ?That solved my TX drivers, gain flatness, and heating

Hi Gyula, You are spot on.? I went down a rabbit hole and thought I was lost.? The act of typing to the group and reading everyone's response helped me reconsider and get back on track. I now have

Great work Guys, both of you! OK, I bet an AMP of that was the rest of the radio, so you're probably down to 7A total (3.5 per MOSFET) Crucial question then becomes: WHAT WAS THE POWER SUPPLY

OK.? ?I have it mostly or all fixed.? ?I went around in a zillion circles, of course. What I found was that in lines 1359 and 1369 else if (!strcmp(cmd, "tx")){ if (!strcmp(value,

Hi Gary: Yes, I worked on it one evening, gave up and went to bed, and tried again the next day. Nada... To all who have tried to help, your efforts on my behalf are sincerely appreciated. It appears

Hi Jack, There's a lot of regulators on that design!? The first one to check is the one associated with microcontroller / power button.? That is U5 a 3.3V LM1117 per the schematic.? I didn't figure

Thanks Gordon and Gary. The 2N2219a drivers get hot enough to burn a finger so I added their own heat sinks, but that’s only a fraction of the total energy so each final may be dissipating over 30

Gordon, I read as total radio current draw = 8.2A, not the current to just the output amplifier FETs. Need to know the FET current.? Otherwise, it leads to a very pessimistic calculation as you have

Greg, Did you get the plateau in the BFO adjustment step?