[Elecraft] K3 Receiver Mute

[Grant Youngman]

Is there a straightforward way to mute the receiver in the K3 from an external "mute" line?  

I want to use the K3 receivers with some vintage transmitters, and am looking for the best way to accomplish RX muting.  Not that an R-390 with a Sherwood sync detector isn't a  good receiver, but summer is coming, and there's enough heat in the shack from other sources  ;)

All I've managed to conjure up is to put the K3 in TEST and then assert PTT from aux contacts on an external antenna relay.  Am I missing something obvious?

Grant/NQ5T