On 12/4/2020 8:25 PM, Jim Lee wrote:
The Becker radios have an internal fuse which can easily blow from the surge if you start or stop the engine with the radio turned on. Make sure the radio is off before doing so. When the internal fuse blows, the only option is to send it to Becker at the above listed address. They will replace the fuse and send it back to you pretty fast.


I am puzzled by that. Why would an overvoltage surge, even if it is up
to, say, 20 volts, blow a fuse? Especially if the radio is not
transmitting at the time. Voltage only causes current if something
accepts it. (Unless that radio has protection circuitry that does that
on purpose.)

The OP said "The tach also mysteriously died and the fuse on the vario
blew". That, together with the radio problem, suggests that something
much worse than an overvoltage surge happened. Or is one supposed to
disconnect the tach too before starting the engine?

"Was working fine and on the next flight nothing after starting up the
engine." - Was it working on the same flight before starting the
engine? If not, I wonder what happened between flights. Battery
briefly connected in reverse polarity?

Once that other issue is (or has been) cleared, then indeed the radio
may need service.