At 11:44 PM 6/14/2005, Dick Frey wrote:
>The Icom's relay is rated at 60V and 0.5A.
>Using this to switch the Alpha's T/R line is about the same as no load.
>The current is < 2mA on key down. That's mouse nuts!
>Go for it, Clive.
I'd be very careful if I were you.
The relay in my IC-756 (non-Pro) is rated (according to the manual) at 16V
@ 0.5A. My Henry 2K (modified with a Kilovac HC-1 and a P&B KHU-style
relay for the input and bias) welded the radio's contacts shut on the first
My IC-746Pro did the same thing with the VHF-style T/R relays on my 144 MHz
8877 amp...fortunately, it later un-stuck and has worked fine since.
The relay in the IC-756 is a DIP model with contacts rated as
described. However, they seem to be intolerant to inductive kick (yes
there was a flyback diode across the relay coils).
All homebrew amps at K8CC now have PNP pass devices switching the T/R
relays. The radio only have to switch ~ 10mA of base current.
It's easy to build a little box to plug into the ACC2 jack on the back of
the ICOMs. I used this for several years until I figured out how to fix
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