[AMPS] Eimac 3CX3000A7 cathode

[Phil Clements]

Subject: [AMPS] Eimac 3CX3000A7 cathode


>
> I always thought that the 3CX3000A7 had a directly heated cathode (a thoriated tungsten
filament), but the schematic for the Henry 8K Ultra clearly shows a cathode distinct from the
filament.  The filament transformer's secondary winding center-tap is grounded, and the cathode
is biased.
>
> What's the story?  BTW, I couldn't find the answer at Eimac's website.
>
> -Chuck W1HIS

The Henry schematic is misleading. There are only two connections to
the base of the 3CX3000A7, and that is the filament, which is indeed thoriated-
tungsten. The 8-K Ultra uses no bias. What you are seeing is the circuit that
rectifies some RF from the input to run the ALC.

(((73)))
Phil, K5PC




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