[AMRadio] Contactor

Rick Brashear rickbras at airmail.net
Sun Sep 16 10:30:48 EDT 2007


That's almost the scenario.  The GE BT-20-A has a mechanical 3 second
(adjustable) overload relay that holds B+ on for 3 seconds if AC power to
the transmitter is interrupted for a second or so (actually 3 seconds) by
lightning or such.  It prevents having to go through the 30 second warm up
required when the transmitter is first powered on or power is temporarily
lost.  The relay in circuit at this time works, but it uses a gear and
clicker mechanism to achieve the 3 second delay and it is quite noisy.  Of
course, it was not designed for use with PTT keying and would likely not
hold up to the constant on/off caused by such.  The way the power around
here flashes on and off it will be a welcome feature!  I will likely set it
for about a second or second and a half delay.


Depends on where in the circuit is needed.  

I'm guessing that the 120v AC relay, that's active as
long as you're transmitting, is making the transmitter
come on, or go off.

Either way, a millisecond or two is about all you
need, and quite negligible.  Just make sure you have
enough capacitor to discharge the resulting spark of
Back EMF from the contacts, when the relay is

73 = Best Regards,

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