Eric Greenwell wrote:
David Kinsell wrote:

The truth is virtually no aircraft radios have upconverters built into
them. They switch high currents at high voltage at low RF
frequencies. A nasty thing to be building into a radio with a
sensitive receiver. The converters put out harmonics from their
high-power square waves going
well into the aircraft band.

I hadn't thought about the noise problem, but I can see it would be an
issue. If they don't use converters, how do the newer radios manage so
well on low voltages? For example, the Becker AR4201 is specified for 2
watts output at 10 volts,

I don't know where you saw that. On their web site, they list the input
voltage as 12.4 to 15.1 volts, with emergency operation only down to 10
volts.


and the Dittel FSG 2T is specified from 11 to
16 volts, with 9 to 11 volts emergency operation.

Yep. In their literature, they also say you must have at least 11.0
volts during transmit.

Sounds like two radios designed for 14 volt operation, just like always.
I wonder how long a 12 volt battery mounted in the tail is going to
supply 12.4 volts to the Becker?? 10 minutes maybe, if you've got good
wiring?? I expect Becker is just a little more honest with their specs,
rather than really being different than the Dittel.


Too bad the
Becker/Dittel engineers don't follow ras, but it does free them to
design more stuff for us.

You've got to keep in mind the soaring market is peanuts compared to
the power market, so that's why radios have been, and still today are
designed to the 14 volt standard. Why put a switching converter in
a radio that's sitting there all day long with a well-regulated, very
stout 14.2 volt supply?

-Dave