On Mar 14, 11:37*pm, Steve Koerner wrote:
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 Koernerwww.wingrigger.com

Nice work Steve,

Some additional information which verifies your findings:

The avionics shop I work for has installed these TRIG TT21 's in 8
gliders so far.....we have three more in line for installs.

We bench test them before install, and our ampmeter shows below 200
ma.

We then tested a glider with everything installed, and using our test
box to continuously interrogate the TRIG.

We also have one of those Astro Flight watt meters! If I remember,
200ma is the highest we saw on the TRIG. We then added vario, then
Comm radio on standby, comm radio on receive, and finally comm radio
on transmit.

I think it was 700ma or 800ma for everything running at full blast.

We did sime calculations figuring the comm at transmit for 10% of the
time, and recieve at 30% of the time and standby at 60%.......and the
vario at 150 ma and the trig at 200 ma..........

This glider has a 12 MAH battery.......should easily run for 12 hours
if fully charged and in good shape.

It is the comm radio which is the power hog, not the TRIG.........Any
glider that is now running with a big enough battery for the equimment
installed, could add a TRIG to the circuit. The additional drain of
the TRIG is almost insignificant. No need for an additional battery
in my opinion. Gliders that already have two batteries really have it
made regarding the TRIG.

BTW........on the bench tests, the TRIG TT21 puts out 125W to 160W at
the antenna cable........Our test rig does not show smaller
increments, so the real output is somehwere between 125W and 160W.


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