[Collins] RE: 75A-3 AVC problem

[Laird Tom N]

Garey, 
the RF gain control has some effect on the voltage, from "stop-tp-stop"
it changes it
from -38 to -40 volts, so that makes me think the control is OK, the
wiring looks
unmolested and I did check the muting control on the rear panel as well
as, the S-meter pot.
Both appear to be OK.

Do you have an A-3? What I need to know is what the correct negative
voltage should be on pin 3
of V-9 with the RF gain at zero and then 10...........

Thanks,

Tom Laird WC9M
Moline, IL.

-----Original Message-----

Tom -

Sounds like it's cut off.  RF Gain control or wiring.  Standby control
or wiring.

73, Garey - K4OAH
Atlanta

Drake C-Line Service Manual
<http://www.k4oah.com> 


Laird Tom N wrote:

>I have a 75A-3 with a "pegged" S-meter. I have checked all the tubes. I

>measured the AVC voltage at V-9 (AVC amp pin 3) and it measures -38 
>volts DC. I think it should be around -11 volts?
>
>Any specific ideas as where to look for the problem. I have checked 
>most the components around that circuit and they seem to be in spec. I 
>also changed the 20uf cathode 'lytic of V-9, still no RX.
>
>Tom Laird WC9M
>Moline, IL.