On Dec 8, 6:59*pm, Eric Greenwell wrote:
On 12/8/2010 4:51 PM, Darryl Ramm wrote:

However that does
*not* get close to explaining the apparent high power consumption
(1.1 Amp!!) of this Mode C transponder vs. the Trig Mode S
transponder.

According to the brochure I downloaded, the remote version of the unit
only requires 200 ma, instead of 500 (still at 28 volts). That's still
pretty high for a version without the encoder, but it makes me wonder
where the 300 ma is going.

Someone could call the company to find out, but really, I see little
value in it when the Trig is so good. If you want to save some money,
offer to buy a used Becker for, say, $1000-$1200, and get one from
someone that's thinking of upgrading to a Trig.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

Either Sandia is quoting numbers for an encoder with heater full on
(unusual to do so), or they have an inefficient encoder design or
their control head draws a surprising large amount of power (for
something with an OLED display), or some combination of all of that.

A good rough number for steady state consumption for an ACK-30 encoder
(what most of us with Mode C transponders in gliders use today) is a
bit over 60mA @ 12VDC without the heater on. Heater full on they can
draw 400mA @ 12VDC (luckily the heater should not be on often in
usual use - but if you are flying in wave especially make sure the
encoder box is insulated and protected from drafts).

But even then even if you were compete nuts and wanted to spend money
on a Mode C transponder today the headless version of this transponder
is still not an option until somebody has a controller that can
control it.

BTW the heater in the encoder built into the Trig TT21/22 kicks in
starting at 4C down to -25C where it is full on. At its peak it
consumes 1.7 Watts (= 140mA @ 12VDC). Very impressive numbers. Data is
from Trig engineering.

I have a pair of very nice electrical heated boot insoles that I
brought for wave flying and they consume almost the same as the spec
on this Sandia transponder implies it does at 12VDC. Possible since I
have 2 x 18Ah batteries, a engine driven generator, and a large solar
panel in my motor glider... but still if I'm going to just absolutely
burn power for the hell of it its going to be for important stuff like
keeping my feet warm not to run this junk.

Darryl