Ed wrote:
> Rick Denney wrote:
>
>>> I would check whatever is in the filament CT.......
>> Ed, thanks for the response. That's what I'm thinking, but I've
>> already checked it all. The AL-811 is simple--there is the T/R relay,
>> the input tank switched with the input bandswitch, and a couple of
>> capacitors that protect the input tank from filament biasing voltage.
>> The biasing voltage is there--the filaments are lit. I was sure it was
>> one of those caps!
>>
>> Rick, KR9D
>
> Where are they applying cut-off bias ?? and is not the metering circuit
> also tapped off the CT ? I would think in a GG amp, there would be zero
> grid current until some drive is applied. Are the grids strapped
> straight to ground or are they floating via a cap/resistor combination.
>
> Is this the 3 or 4 tube version ??
>
> Ed W3NR
I just went to Ameritron's web site, the 811 is about the most basic GG
amp there is. The design is a proven, reliable circuit. The amp could be
copied from just about any Handbook circa the 60's. On the B- side of
the HV is a diode D16 according to the schematic in the metering
circuit. Its a 1N4007, make sure it isn't open.
Also check the 2.5mH choke, L3 on the output of the tank circuit.
Other than that its time to pull the tubes and check them for shorts.
Ed W3NR
PS Don't forget that Ameritron is well known for leaving connections
totally un-soldered or poorly done solder joints. Their QC is terrible
to say the least.
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