[ARC5] Solid state R392

[Mike Kana]

Thank you for posting this info. I have a pair of 392s and have hesitated in solid stating them as tube sets still seem common$. One has the WeCo solid state audio amp.  I would be fine leaving the front end tube and SS the rest. 
In the Low And Medium Frequency Handbook, there was a solid state Q5’er design. I’ve been on the fence to convert as the B+ has been satisfied with a daisy chain of 9v dollar store batteries and the radio already has the 12v filament mod. 
73 Mike

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> On Aug 31, 2025, at 6:09 PM, J Mcvey via ARC5 <arc5 at mailman.qth.net> wrote:
> 
> 
> Hue asked. so here is a copy of my original notes.
> 
> This project was born of the desire to get rid of that power wasting dual pentode that produced so much heat. (heater draws 15 watts!).
> I used IRF640's which are a bit of an overkill, but I had them on hand.
> 
> Then, since the radio plate voltage is 24 volts, I figured it wouldn't be much of a stretch to replace other tubes as well.
> Some I was able to get away with "drop in" replacement.
> 
> I crushed up some old computer "D" plugs to harvest the pins to use for plugging the transistors into the miniature tube sockets.
> 
> The only tube replacements that gave me problems were the RF amps because they had to work properly with the AGC.
> I tried a cascode configuration with limited success but didn't work well enough. I did not try dual gate fets yet. Those will probably work.
> 
> This project was done about 4 years ago. The RF amp tubes are still there because I never got back to figuring it out.
> Any suggestions?
> <R392_solid_state.jpg>
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