[Boatanchors] Suppressor grid modulation

[revcom at wbsnet.org]

In the early days of SSB amps (economical ones) the 1625, by some
manufacturers had the suppressor on a seperate pin, while those, if I
remember right by RCA, the JAN tubes did not.  You ground a hole in
bakelite base and carefully disconnected the screen grid wires and
rerouted it. That way you could operate them in a Grounded Grid amp.

P&H had an smp using them, about 400W. I think the 837 was about the same
but did not require modification and had a 6V filament.  Memory gets
cloudy after all these years.

Sure made good use out of all the surplus 1625s laying around.  Used to be
able to buy them by the 100 lot fairly cheap.

Rod
KØEQH



> On Wed, 27 Jan 2010, Al Klase wrote:
>
>> In addition, you need a pentode with the suppressor grid brought out to
>> a separate pin, as opposed to being internally connected to the cathode.
>>
> This ticked a faint memory of some article about tubes, 807 or 1625,
> and in some brands there was something connected internally, but in
> others there were two separate wires going to the same pin on the base.
> So if you had that kind you could carefully remove the base and
> separate the two wires and do something useful with it.
>
>
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