Short circuit ?

[Paul Cannell]

Just had the VHF & Plotter replaced, both are connected to the same switch as was the old combo, both units working fine last week, until yesterday when as I keyed the Mic both units turned off only to restart after releasing the Mic key,
Any advice to fix or locate problem please.

[Ajsimp]

Sounds like too much current draw for the wiring or a bad connection. When you key the mike is the point a radio draws the most electricity. I would start by checking the wiring and every connector from the switch to the vhf & plotter, if they all look good check from battery to switch. If they all look ok I would make a new supply & earth for each unit separately

[Firefly]

Originally Posted by Paul Cannell

Just had the VHF & Plotter replaced, both are connected to the same switch as was the old combo, both units working fine last week, until yesterday when as I keyed the Mic both units turned off only to restart after releasing the Mic key,
Any advice to fix or locate problem please.

I suspect you are getting a voltage drop across the common switch. Could be elsewhere but I'd start with the switch. short the switch out with a wire link and try transmitting. If all is ok with the switch shorted out, replace the switch.

[Paul Cannell]

I agree on bad connection at the switch, all good before new stuff fitted,
There are 3 spare switches will check the common one but rewire to separate switches for peace of mind.