Greg Arnold wrote:
Martin Gregorie wrote:
On Sat, 16 Aug 2008 11:16:47 -0600, Bill Daniels wrote:

I have a Microair and, as long as you feed it 11.5V, it works fine. Up
and down the flightline it seems that every radio brand has it's share
of problems. Gliders are a harsh environment for complex
electronics. Be thankful radios work at all.

I suspect airplanes are worse than gliders; after all, there is no
vibration, no spikes on the voltage supply, and likely less heat under
the panel (no engine heat and less electronics producing heat). The
wring installation may be worse, typically. TSO'd radios have to meet
some very stringent electrical, mechanical, and environmental
requirements, so I expect them to work almost perfectly in a glider.


Has anybody tried putting a solid state DC-DC converter in the
Microair's power supply?
Devices exist that can easily supply a constant voltage in the range
12-14v at whatever current the radio requires, even when the battery
drops to 10v.


Does the Dittel FSG 2T have one of these? It is advertised to work at 9
volts, and my experience is that it continues to work fine even when the
voltage during transmission is below 10 volts (and the vario is going
crazy due to low voltage).

TSO'd radios (like the FSG 2T) have been required to work in the 9-10
volt range (at reduced power output) for about 20 years. They may use a
DC-DC converter to achieve this, but I don't know which ones do. Some of
radios obviously do, such as the Becker 4401 transponder, as they have
wide range power supplies that also work up to 30 volts or so, while the
power input remains constant.

The Microair isn't TSO'd, so it doesn't have to meet this low voltage
operation spec (nor does it claim to), which likely explains why there
are reports of low voltage operation problems. It might benefit from a
converter, if it has problems above 11 volts.

--
Eric Greenwell - Washington State, USA
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