AT1 Question

[Mark S Graalman]

  I'm not familiar with the AT1, but it may be possible that
in the original setup the Oscillator and final were cathode keyed
at the same time, and when you placed the oscillator cathode to
ground you also keyed the final and if there is little or no RF
drive present then no grid leak bias can be developed and
thus the high idle plate current.

Mark  WB8JKR


On Tue, 23 Mar 2004 09:27:14 -0800 Rinkie & Ron Pollack
<rinkies at ADELPHIA.NET> writes:
> I am about finished restoring an AT1 in nice cosmetic condition, but
> someone
> has converted it to a 6146 final.  (Why, I don't know!)  It works
> great with
> a crystal, but when I short out the cathode to ground on the
> ocsillator tube
> to use with the VFO, as instructed, the plate current pegs without
> the key
> being pressed.  I'm not too technical a type, but it seems that
> perhaps the
> final is self oscillating? Is there a way to use the VFO without
> bypassing
> these parts?
>
> I would like to convert this back to 6L6 operation, but don't know
> if the
> amplifier coils have been modified.  Anyone know anything about this
> conversion, or how to tell if the coils have been modified?  I have
> a copy
> of an old QST article describing conversion to a sweep tube (I
> think) that
> requires coil mods.
>
> Thanks for any advice!
>
> Ron K2RP
>
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