Re: T/R Switching

Bill Cromwell


I have come to prefer separate transmitter/receiver operation. I also
prefer to listen to my transmitter instead of having just a sidetone
audio oscillator (CW). In any case when I changeover from transmit to
receive the receiver antenna terminal(s) are directly grounded. Even if
I have a separate receive antenna that is still something I do.

My "pretty" receivers are setup to completely mute everything from the
antenna up to the audio stage and audio is left on for the sidetone. I
have used receivers that don't quite silence the rf/if stages and allow
us to set the level that can come though - *almost* silenced. The
receiver oscillator and mixer are running and the amplifiers are mostly
shut down. The transmitted signal becomes the "sidetone". I am modifying
my reveivers that don't work that so that they will. When we operate
that way we will notice anything that isn't just quite right including
"forgot to net the TX". Don't ask me how I know that (evil grin).

It's possible to do all of that with full break-in QSK or semi break-in.
I have come to prefer a manual switch that changes everything over for
the T/R functions. It is the easiest to implement and the most reliable.
I have a set of Kenwood Twins that are setup with the transceive cable
and semi break-in using the VOX. On that rig I just use the manual T/R
switch on the front panel of the transmitter..same as all the rest.
Sometimes the QSK process cuts off part or even all of the first dit and
if the first element is a dah it can become a dit. The manual switch
eliminates that. The first tap of the key is already live.


Bill KU8H

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