[Collins] 32S-3 no CW keying

[Dr. Gerald N. Johnson]

On Sun, 2009-10-04 at 19:47 +0200, Jan Erik Holm wrote:
> Looking for some ideas where to find this problem.
> In CW VOX doesn´t work, however when using PTT
> and then key TX I can hear CW in a spare RX
> however no power output and plate current just
> sits on the idling point.
> In SSB mode all is OK and VOX is also OK.
> Replaced tubes, no tube problem.
> I understand I need to do measurements and normal
> fault finding but first I just wounder if someone
> have had a similar problem.
> 
> 73 Jim SM2EKM

In the 32S-3, the CW carrier comes the USB crystal and feeding that RF
directly to the first mixer. It does not go through the balanced
modulator or the mechanical filter. The audio tone oscillator supplies
sidetone to the receiver and operates the VOX, nothing more.

My first guess would be oxidized contacts on the mode switch. A quarter
drop of DeoxIT on each contact followed by some vigorous operation
should clean them up.

You do have to turn up the VOX gain for CW, just like for SSB.

My second guess is the USB crystal, and CW should tune and drive just
like tune, or lock key which is full power to the PA screens. The only
difference for CW is the key line is grounded by the external key for CW
and by the mode switch when on tune or lock key.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer