[Elecraft] RE: Request for info - integrating 2 K2s to achieve "2nd RX" capability

[Don Wilhelm]

George,

Unless the separate antenna picks up the full power of the transmitting 
antenna, you should not encounter any damage.  As was suggested, a relay 
driven by the KPA100 Amp keying circuit could break the antenna 
connection.  The Amp keying output conducts 15 to 20 ms prior to the 
onset of RF output.

Your biggest problem will be in muting the 2nd receiver.  Again the 
KPA100 amp keying circuit can be the initiating element.  On the K2 
control board, the /MUTE signal from microprocessor (U6) pin 17 drives 
the gates of Q6 and Q7.  If you break that signal path and insert a 
series resistor (5k to 10k) to protect the microprocessor output, then 
  you can mute the K2 from an external source by grounding the gates of 
Q6 and Q7 when the other K2 is transmitting.  Use of a series diode in 
the path of the external muting signal with the anode connected to the 
gates of Q6 and Q7 would provide isolation.

Several builders have tackled similar situations, and a search of the 
archives may give you some additional insight, techniques, and 
information about the results.

73,
Don W3FPR

JONES, George wrote:
> I have acquired a 2nd K2 (via a rally sale) so now have my K2/100 main rig plus a K2 "QRP" rig.
> One set-up that I would like to try is using the 2nd rig as an integrated 2nd receiver.
> It has "RANT" & I can use separate aerials (antennas) - any advice/cautions would be welcome. I absolutely don't want to destroy anything in either rig !
> 
> Note : I have never owned or used a "high-end" rig with this in-built capability
> 
> 73
> 
> George G4TPV