[MRCA] T-195 Slow Semi-Break In Turnaround Time on CW

[Christopher Bowne]

.....What is odd about the way my set is behaving  is that there is  no observed 
delay in antenna switching to the receiver or receiver  de-muting (which is also 
controlled by the relay) in voice mode PTT  operation when releasing either the 
test key or mic PTT switch after a  transmission.  The circuit as described, 
should operate the same no  matter what mode is used, and and I have not found 
any mention of any  differences in T/R switching that are mode dependent...... 


Did some more study of TM 11-806 and nuc'd out the reason for no antenna delay 
relay hang time issue in voice mode.  In voice, the LV dyno, which supplies both 
the +250V for the plate of the antenna delay relay switch tube is powered up by 
closing the test key/PTT line to and is turned off when the circuit is opened up 
when going to receive.  So, no LV to keep the relay pulled in!  I had always 
thought that the dyno I  hear spinning up on going to transmit in voice mode or 
on selecting CW mode with the mode switch was the HV dyno...once again, it pays 
to RTFM!  Reading this manual really gives you an appreciation for the genius of 
the engineers at Collins who designed this rip roaring electro-mechanical marvel 
of a transmitter!  Now to figure out how to get at the delay relay circuit to 
tweak the RC time constant.....
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