[Collins] AADE digital dial on the KWS-1?

[Dr. Gerald N. Johnson]

On Sat, 2009-04-18 at 11:47 -0500, Dennis Petrich wrote:
> I am installing the AADE C75 digital dial on my KWS-1 and notice it's loading down the VFO and HFO injection points so the KWS-1 doesn't want to output any signal.  The AADE digital dial works just great indicating the signals are always present.  When I remove those two connections the KWS-1 works just great.
> 
> Has anyone on the Collins reflector had this experience?  I don't want to make any adjustments to correct for the coax load if I don't have to?
> 
> Dennis, k0eoo

The outputs of the crystal oscillator and PTO are very high impedance
points. 100K grid resistor on the mixer for load. A coax connected
counter is a killer on that high impedance. Not at all like the
oscillator outputs in a 75S or 32S that are low impedance and stand
extra loads.

The coupling capacitor from the PTO is 24 pf, less than the capacitance
of one FOOT of coax. The coupling capacitor from the crystal oscillator
is 5 pf. Way less than the capacitance of a foot of coax. If the counter
is sensitive enough, you can try a small coupling capacitor at the coax
connector in the KWS-1, like 5 pf for the PTO and 1 pf for the crystal.
Else you may have to build follower circuits to match the coax to the
high impedance oscillator circuits.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer