[Heathkit] More. . .AT-1 woes

[Donald Spoon]

I recall a similar problem when I first put mine on the air.  The 
"problem" wasn't really a problem but just  a wiring choice.  The 
construction manual gave you a choice of keying both the 6AG7 and the 
6L6 or just the 6L6 final.  The manual implied that keying only the 
final was "better" because there was a much less chance of chirp.  I 
tried both ways and it didn't appear to make much difference when using 
a  crystal.  I would imagine yours is wired for the 6AG7 oscillator to 
run all the time once the B+ is turned on.  See if the 100 Ohm resistor 
in the cathode circuit of the 6AG7 goes directly to ground or to the Key 
Jack. 

-Don Spoon-
K0APK

bfetters at aol.com wrote:
> Thanks for all the inputs re: my AT-1.  Consensus is that getting 10-15 watts out is about normal.  I'll leave well enough alone on this issue.
>
> Found another problem when I turned on a receiver to listen to the signal.
>
> When I turn on the B+ switch to operate, the unit self oscillates.  I can hear it softly in the receiver and when I key the AT-1, the tone changes a bit and gets louder.  Checked for a leaky cap from the key to ground and it seemed okay.  Also disconnected the small cap from the cathode to ground of the 6L6.  (The 6L6 cathode is keyed.)  When I turn the driver variable condenser I get a slight change in pitch/intensity of the self oscillation.
>
> Any thoughts on how to get this self oscillation stopped?
>
> Thanks again.
>
> Buck
>
> W0LC
>