[Collins] new subscriber with a 75A4

[Barockteer@aol.com]

The A4 does address several of the problems you mentioned in order to achieve excellent performance on SSB. It has fast attack-slow decay AVC. It also has separate detectors for AM and SSB, with the SSB detector being a mixer type using both sides of a 12AU7 in a common-cathode configuration for isolation between the IF signal and the BFO.

It's interesting to me that you can't always assume that Art Collins and Co. had everything working just right. Although the stock A4 is an excellent SSB receiver, the muting setup left a long transition when going back to receive due to overcharging of the AVC circuits. Even paired up with it's matching KWS-1 transmitter, it's hard to believe Art let it out the door that way. The aftermarket AVC mods fix address this problem, but no Service Bulletin was ever released covering it.

-Tony, K1KP