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Keying	Reply
by KF6BKA on May 15, 2008	Mail this to a friend!
I am looking to build a Mic controller so I can run 4 radios from one mic. I know from my experience that when you key a mic it closes a circuit and provides either voltage or ground. Is there a standard in Ham radio about which? I have Alinco and Icom radios and I know that both mics get voltage but I think they are ground keyed, right? Rich

RE: Keying	Reply
by WB6BYU on May 15, 2008	Mail this to a friend!
The best best would be to use a 4-pole switch that provides separate wires for mic and PTT switch (two wires each.) Make sure your mic supports that, too. Sometimes you get a radio where neither side of the mic circuit can be grounded, or where the PTT switch is isolated from ground. Switching all the wires prevents problems where one mic has + voltage on the mic wires and another has one of them grounded. Otherwise if you plugged both rigs to your switch box it could burn out the voltage regulator or audio preamp in one of them. This way you can wire up a plug for each rig with no interaction.

RE: Keying	Reply
by W8JI on May 16, 2008	Mail this to a friend!
Keying normally pulls the mic pin to ground. Virtually all modern radios work this way. Be sure the supply voltage is correct for the mic.

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