On Mar 1, 2:35*am, Charlie Papa wrote:
I have a Discus 2cT with about 650 hours on it. *Schempp-Hirth did the
instrument installation, and a more professional looking job you will
not find. *But there was one problem that confounded even the avionics
guy: when the engine was running, pressing the push-to-talk button
would kill the engine until the button was released.

The engine's ignition is a very simple magneto (Solo 2350), and the
radio a Dittel FSG2T radio, - yes, the one with a recall. *How to
explain the ability of the radio to ground the magneto?? *No one even
had a theory. *But when I reinstalled the radio after the recall
service (which was very efficiently and courteously handled by Dittel,
BTW), the problem was gone. *I tried to induce the problem several
different days, but it exists no more.

So what flaw in this radio can cause such an effect? *A black curse?

No, the engine electronics will shut the ignition down when max. revs
for the prop are exceeded. The revs are present in the instrument as a
proportional voltage signal (1V = 1000 RPM) and i'd bet that somehow
the electronics got tricked into thinking that it was the case. A
voltage drop in the power supply from the battery during radio
transmission or an induced spike from the radio's RF power could have
been the reason.