[Collins] 75A4 and SB 610

[Dr. Gerald N. Johnson]

On Mon, 2007-06-11 at 12:33 -0700, w6om at cox.net wrote:
> I have a beautiful 75A4 and a beautiful Heathkit SB 610 monitor scope with a 455 KC IF. Looking at the 75A4 schematic it would appear that it is would be simple to connect the scope to the grid of one of the 455 KC IF tubes through a small capacitor so it does not load down the receiver IF strip.
> Anyone with an "A4" ever accomplished this, if so which grid did you couple the SB 610 to and what formula did you use choosing the coupling capacitor value.
> All the Best
> --
> Ron Weaver - W6OM

The proper place to connect is the plate of the second mixer. Any place
downstream is after the selectivity and tells little about the incoming
signal because the mechanical filter cleans up bad signals.

Usually a few PF is all it takes, the monitor scope has good
sensitivity.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer