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In older commercial grounded grid amplifiers, it is common to see a cahngeover relay used to switch between a zener diode or similar bias regulator and a bias cut off resistor. My question is, why did

Before retiring and while still active in the field, precision D.M.M.'s were important, not in themselves, per se, but as a reference point in any possible report ensuing from having to have employed

GM3SEK? Here is a link that turned up. No longer sold it seems, and a quick search for gerbers turned up nothing for me. The schematic is in the manual so one could do a board run if so inclined. Bob

http://www.ifwtech.co.uk/g3sek/

Attached to this email are the manuals for the G3SEK tetrode and triode boards as well as the tetrode board design documentation. Maybe the moderators can add these to the group files section.

Mike, Try this: https://web.archive.org/web/20180408212726/http://www.ifwtech.co.uk/g3sek/boards/tetrode/tetrode-1.htm 73 Bill N4LG

Hi, Would anyone have the G3SEK schematic and PCB drawings for download? The link seems to be broken for me: http://www.ifwtech.co.uk/g3sek/boards/tetrode/tetrode-1.htm Cheers, Mike Peace VK6ADA

I have ran into a couple of those online. Wanted to put one in my Thunderbolt, as it uses the gas filled tubes to regulate the screen, but I was gonna try a string of Zeners soldered into an old tube

The tetrode boards aren’t particularly complicated if you only implement the screen current trip. On my tetrode amplifier, I eliminated the control grid current trip and ALC circuitry. Their primary

Can't beat the simplicity of a triode amplifier.

Sell your 4CX250's and purchase the 3CX400's ?

Main reason for looking into the 4CX250 is I have a ton of them, like 10-12 of them, sockets and chimneys as well. My father-in-law who is also my elmer built an amp around the RF deck of a KWS-1 that

I cut my teeth bringing an old Johnson Thunderbolt back from the grave. (2) 4-400A tetrodes in parallel....learned a lot. Key to that whole applicaiton is the neutralization....and the fact if the

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

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

You can buy many decent RMS multimeters like the Brymen BM857 that is a fully safety rated and protected meter that is much cheaper than the Fluke. There are others.? There is a Multimeter comparison

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

I located a spare Johnson #247 socket (8877). Never been soldered on. Make offer.. Dennis, w8nw [email protected]> wrote:

###? ?If I remember correctly, the 1st DTR-2000L's had this mickey mouse fan in there for cooling.? Local dealer had the 1st one in stock.? ? We all laughed when we saw the small fan...that