[R-390] QSK; standby reduced fil. voltage; separate B+ on/off

[Gord Hayward]

I use a sequencer for PTT lines - key the microphone and the sequencer 
pulls in the T/R relays which connect the TX to the antenna, ground the 
RX input, mute the RX
using its break in relay, THEN, 200 milliseconds later, it keys the 
transmitter (my Viking II is the civil defense version which has PTT).  
Letting the mic go reverses the process
with the same 200 msec delay. I use an inrush limiter but its in a 
second box with the stereo product detectors.  The 390A plugs into this 
box and uses its power switch.
Cheers, Gord, VE3EOS

-- 

Gordon L. Hayward, Ph.D., P.Eng.,
Associate Professor, Biological Engineering,
School of Engineering, University of Guelph,
Guelph, Ontario, N1G 2W1.