Mel and all,
That is certainly a way around the hot-switching problem, and works fine
when you are using the microphone PTT switch - but does not work for QSK
CW or VOX operation.
There *are* relays and T/R switching devices that switch faster than the
KX3/KXPA100 Key Out to the onset of RF time. Of course, a selection
based on details such as relay pull-in and dropout times must be
investigated, but are readily available in a study of the relay
specifications.
73,
Don W3FPR
On 11/22/2014 4:34 PM, Mel Farrer via Elecraft wrote:
Any RF horse race is a bad choice. I prefer to do the simple sequence
switching. A single relay that is keyed by the PTT line with one set
switching the loop off and the Tx antenna ON and the other set of NO contacts
on that relay keys the KX3 and Amp. I built a little TR cast AL box that has
the KX3 mike plugged into it and a short cable with the 4 conductor cable to
the KX3. The box has the cable from each antenna and the plugged into it. I
use a 12 VDC jumper into the box to supply the relay . Simple DPDT crystal can
relay on a perf board is enough to handle a couple of hundred HF watts. The
third RF cable goes the the output of the KXPA100. I love KISS,
Mel, K6KBE
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