Pete,
Connect one side of the relay coil to your +12 volt supply, and connect
the other side to the KEYOUT jack. Put a diode with the cathode
connected to the +12 volt side across the relay coil. The negative of
your power supply has to connect to the shell of the KEYOUT connector.
The relay will be activated when the K3 KEYOUT is active - keying, TUNE
and PTT will all activate it.
Yes, you should be able to use the same +12 volt supply to power the
SDR's preamp and active antenna, but that is a different consideration
than activating the relay.
73,
Don W3FPR
On 10/14/2017 10:18 AM, N4ZR wrote:
Thanks, everyone who responded to my earlier query - I now understand
that the circuit in the K3 is equivalent to the old bipolar transistor
switches we used to use for serial port CW/PTT keying.
So here's my problem - I have a small 12V DPDT relay that I want to use
to switch the power to my SDR's preamp and active antenna - in other
words, to cut them off when my K3 is in transmit. What I can't figure
out (be patient with a history major, please!) is how to use the Key Out
jack to switch the power to the relay , while using the same 12V supply
to power both the relay and the preamp/active antenna combo.
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