[Milsurplus] AT-12 Photo

[Richard]

Postscript:

Looking at the At-1 book, it shows pin 4, the suppressor grid, directly 
connected to one side of the filament.  One could directly ground pin 4 
for an 807, but that bypasses the plate metering circuit, or use it 
as-is, as the filament is heavily bypassed and should work fine.

RB, AA1P


On 03/08/2017 03:52 PM, Richard wrote:
> The 814 has a small 5-pin base, the same as an 807, so it's an easy 
> change.  However, the 814 is a beam-power tube, which is not so 
> sensitive to plate voltage, and will probably work fine down to 500 
> volts.  Overall efficiency will not be great when you're putting 32.5 
> Watts in each filament.
>
> Richard, AA1P
>
>
> On 03/07/2017 03:59 PM, Hubert Miller wrote:
>> I haven't seen my AT-12 manual in many years but as i recall the 
>> transmitter runs two 814 in the final.
>> I believe the socket is the same as the 1625 and i thought maybe use 
>> 2 of those instead, to be more compatible with
>> power supply parts i am likely to have.
>> -H