I would get the 3CX800 checked out and if good go with that. Socket is the same, filament voltage would need changed and maybe the bias. That should be it. Look at all the Alpha amps that have been changed from 400 to the 800 tubes. Must be a good reason.
On Saturday, December 28, 2024 at 10:21:49 AM EST, Robin Midgett via groups.io <robink4idc@...> wrote:
Hi Billy,
I'm not an amplifier guru. I've studied & repaired a few. There's a notion in the RF amplifier camp that says "if your amplifier needs more than one tube, you need a different design." I agree with that line of thinking.?
If you're going to make the leap from triode to tetrode at the 400 watt /tube?dissipation?level, consider the 4CX400 or Russian GS-36b. They can be had for ~$100 each. Look into the mods online for the AM-6154 / AM-6155 FAA amplifiers as a starting point.
On Fri, Dec 27, 2024 at 8:03?PM Billy Pickering via <pickeringw=[email protected]> wrote:
Well, I was lucky enough to pick up a Henry Tempo 2006 that did not have any tubes. Yes, 3CX400A7 tubes are expensive so we were looking into modifying it to run 2 or 3 4CX250B tubes instead. I know we need to have screen power for these tubes, and was wondering if anyone was currently making the GM3SEK tetrode control boards. I guess we could come up with something from scratch, but those boards are really nice.
?
I guess if it really come down to it, we could modify to run the single 3CX800A7 we have, but not sure if the tube is any good as it was pulled from a commercial unit.
