Ameritron 811H

I brought a Linear amp from Germany, it was well packed, no dents or bumps, but all the valves had come out of there sockets and one had smashed.

I sent the seller a message, and he was good, within a week I had 4 new 811A on my door step.

I cleared out the glass from the amplifier, which is quite hard as it is so heavy,

And Proceeded to put in the new valves, and also checked it was on 240v

I switched on the Amp nothing connected, HV was 1.85kv, also the grid current was 40ma, before I had the the chance to switch of, there was a loud crack sound.

So I powered down took of the covers, and switched back on, including the cheat switch, and the two back valves, where not alight.

I checked the first valve heaters ok, and no shorts to grid, I checked the second valve, heaters open circuit, and one of the heater pins was shorted to the grid.

After replacing the valve that measured ok, and put back a second hand valve, switched on all valves were alight HV Normal, no Grid Volts.

I applied 5 watts RF to the amp, and got out 140watts

As I dont have a power meter that is higher than 150watts, I used an fc902 ATU, and applied 25watts, and achieved 400watts output.

There is no bias adjust on this Amp, So I assume that all 4 valves must be of the same gain.

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