[ARC5] Keying Approach

[Robert Eleazer]

Here is a question about something I have wondered about for some time. >From what I have seen, aircraft PTT mikes typically use a DPST and key BOTH the mike line and the PTT line.  In other words, the mike is not connected to the transmitter until the button is pushed that also grounds the tip of the PL-68 and completes the transmit keying circuit as well.

I am aware that some amateur radio transceivers simply turn the mike on with the PTT switch in series with the mike and that completes the circuit required to cause the transmitter to come on and the receiver to go to standby.  

Is it possible that the aircraft PTT approach reflects that on some transmitters just connecting the mike to the transmitter is enough to turn on the transmitter or is there some other reason?

Wayne