[Boatanchors] Antenna Relays & T-R Switches

[Michael D. Harmon]

Hi,

I know most of the original stations operated back in the Fifties and 
Sixties used the venerable Dow-Key antenna relay, connected to the 
110VAC line from the internal PTT relay.  However, back when I was a 
Novice (late Sixties), I built an electronic T-R switch to use with my 
DX-40 and HQ-110.  I was a poor college student and couldn't afford to 
buy a real Dow-Key!  I seem to remember that I was one of a very few 
guys to actually have QSK capabilities back then.  Granted, the DX-40 
input was only 75 watts (with a good 6146), but it worked fine.

Now after all these years later, I've gotten the boatanchor bug, and 
have a National NC-300 receiver and a Viking Valiant transmitter I'm 
rebuilding for the "ultimate" boatanchor station I would have given an 
arm and leg for back when I was a teenager.  After looking at the prices 
and availability for the Dow-Key relays, I'm very interested in (once 
again) pursuing the electronic T-R switch alternative.

Have any of you had success using an electronic T-R switch with a 
transmitter having the power of a Valiant?  Can I get enough isolation 
in a vacuum-tube design to allow me to monitor the receiver output 
between dits with headphones without destroying my eardrums with 
switching transients?  I'm open for any suggestions, tips, or advice, 
since I haven't tried this since 1968!  (Wow ... forty years ago!!).

Anyway, if any of you have ideas, designs, etc., send them along.  I'm 
interested.

Thanks!
Mike, WB0LDJ
mharmon at att dot net