"Willy VINKEN" wrote in message ...

Power can be supplied to Model 20 through the RJ11 connector and/
or a reverse-polarized barrel connector. In the ASH25E imported from
Italy, one is connected to the avionics battery and the other to the
engine battery. Can both be left connected at the same time?
If both power lines had diodes in series inside the unit, this would
prevent current flowing between the batteries, with the added benefit
of powering the appliance with the highest voltage.

I'd check that very carefully. It's not likely there are diodes in there,
and you could end up with high current flows through the instrument.

Dave