"afcsman" wrote in message
. ..
Now that you're reassured about receiver safety, please let me know about
your experiences with that Old-timey switch. Years ago, I used a similar
one with my Hallicrafters HT-37 and Drake 2B. I found that the Xmtr's
resonant tank circuit produced a null that went through the T-R switch,
and pulled down the 2B's sensitivity. I eventually abandoned the
Electronic switch for a relay.

Jerry, W9NPI
Jerry,
I've seen references to an article in QST about changing the length of the
coax between the transmitter and the switch when that happens. I used a
homebrew version of the T-R switch in the early to mid 70's with a Valiant
II and HQ-170A and never noticed a problem. But then I don't remember ever
checking to see if the receive sensitivity went up when I detuned the tank
circuit. If I run accross the information about which issue contains the
article giving the analysis, I'll post it here. One thing that can be a
problem when using the T-R switch with modern amplifiers that aren't class C
is that amplifier noise will get into the receiver if the amp isn't biased
off during receive. I've seen this on the scope while doing tests using my
JST-245. I'm planning to use it with a Collins 310B, so noise shouldn't be a
problem.
73, Bob AD3K