As an aside--I have a Dittel FSG71M in the portable base station case(the PS
model) with battery and charger built in. It works very nicely. It has a 12v
7.5 ah battery---factory designed and integrated. This is a "spare no
expense" outfit and I think the Dittel engineers would make it any voltage
they wanted.

--
Hartley Falbaum
"Tim Mara" wrote in message
...
Actually.the Walter Dittel FSG2T and previous models FSG70/71 do in fact
have some more sophisticated circuitry that does allow it to operate at a
lower voltage than the Becker does and both are a bit more sophisticated
than others like Avionic Dittel, Filser and Microairs (just to name a
few). Any of these radios will operate at lower voltages at some reduction
in TX output power.but all have more than enough Tx power for our purposes
anyway....you will notice at very low voltages microphone audio becoming
distorted as a first indication that the input voltage has depleted too
far and though at this point it's already too low a battery capacity and
will soon become worthless anyway.......and at that point only PFM would
allow it to function acceptably, it becomes rather relative.no battery
left..no radio
tim

Wings & Wheels
www.wingsandwheels.com


"David Kinsell" wrote in message
...
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