Trig TT21 transponder draws only 125 mA!

I know that a number of folks have been waiting for hard data on the
current consumption of the new Trig transponder in actual operating
conditions.

I measured the current consumption today on an actual flight of 2
hours 52 minutes. The flight was in fairly congested airspace all
within 10 miles of Turf Soaring school which is located just outside
the Phoenix Class B airspace. In fact, some of the flight was under
the class B shelf. The transponder was continuously on in ALT mode.
I noted that it was being interogated at irregular intervals that
averaged about once every one or two seconds.

I have two batteries on board. For the test, one battery was powering
only the transponder. I had an Astro Flights watt meter connected to
the battery which functions to integrate the current consumption and
reports actual Ampere Hours of battery draw. Total draw for the
flight was measured as .353 AH which calculates to 125 mA average over
the duration of the flight.

Here's a reference to the Astro Flights watt meter for those that
might be interested:
http://www.astroflight.com/index.php...=index&cPath=2

I'm an EE and I have independently verified the accuracy of my watt
meter against a precision lab instrument.

Steve Koerner
www.wingrigger.com