[Elecraft] 160M Receive and Transmit Antenna Switching help

[Mel Farrer via Elecraft]

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 <w3fpr at embarqmail.com>
 To: elecraft at 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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