[Elecraft] P3TXMON

[Alan Bloom]

On 07/25/2015 01:01 PM, Dr. William J. Schmidt, II wrote:
> I suppose the next thing we'll need is an outboard box to switch 3 P3TX
> sensors automatically keyed off the ACC connector (amp off HF, amp on HF, 2
> meter).  Hmmmm. I wonder if anyone else has thought about this?

You can buy manual RJ-45 switches on Amazon.  I just ordered one to try 
out.  10 bucks plus shipping:

http://www.amazon.com/Network-Output-Manual-Sharing-Switch/dp/B00AUB3SSA/

If you wanted it to switch automatically you could probably modify one 
of these boxes with your own relays and decoder circuit, or just build 
one from scratch.

There are 8 pins on the connectors.  Power and ground (pins 1 and 3) 
don't need to be switched: just wire all in parallel.  VSCL (pin 4) is 
not used in the P3 and can be left disconnected.

So for each sensor you'd need one 5PST relay to switch SCALE, SENSE, 
VREF, VFWD and VREV (pins 5, 7, 8, 6 and 2 respectively.

Alan N1AL