Correct Don,
He didn't indicate that type of operation so I centered on the simple approach.
If I were going to do QSK or VOX, I would have designed it with PIN diode
switching.
Mel, K6KBE
From: Don Wilhelm <w3...@embarqmail.com>
To: elecraft@mailman.qth.net
Sent: Saturday, November 22, 2014 2:01 PM
Subject: Re: [Elecraft] 160M Receive and Transmit Antenna Switching help
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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