New Transponder for us

Is this an alternative?
http://www.sandia.aero/?q=STX165

Hi,

The Trig TT21 and TT21 are similarly priced (a little more expensive) but
has proven to be a fantastic product. Also, its control head fits into a 57
mm instrument hole, or a smaller hole.

It would be interesting to compare the current draw of the 2 brands. I'd be
surprised if the Sandia unit uses less power than the Trig TT21.

Best Regards,

Paul Remde
Cumulus Soaring, Inc.

"Ernst" wrote in message
...
Is this an alternative?
http://www.sandia.aero/?q=STX165

On Dec 8, 10:24*am, Ernst wrote:
Is this an alternative?http://www.sandia.aero/?q=STX165

Ernst,

Other than it is square, it looks like a good option.

Craggy Aero will be selling them. They will probably be available
around 2/1/2011 and will be priced less than $1700.

Specs look similar to the higher powered Trig and it really is a one
piece transponder.

Thanks,

Richard
www.craggyaero.com

On Dec 8, 11:24*am, Ernst wrote:
Is this an alternative?http://www.sandia.aero/?q=STX165

Why would anyone buy a mode C transponder when for only a little more
one can buy a mode S unit?

Andy

On Dec 8, 11:21*am, Richard wrote:
On Dec 8, 10:24*am, Ernst wrote:

Is this an alternative?http://www.sandia.aero/?q=STX165

Ernst,

Other than it is square, it looks like a good option.

Craggy Aero will be selling them. *They will probably be available
around 2/1/2011 and will be priced less than $1700.

Specs look similar to the higher powered Trig and it really is a one
piece transponder.

Thanks,

Richardwww.craggyaero.com

OK I'll play this game. The specs look *nothing* like the Trig TT21/22
starting with...

1. This is a Mode C not a Mode S transponder.

2. The brochure lists 500mA power consumption at 28VDC. Assuming
perfect power supply behavior that translates to 1.1 A current draw at
12VDC. That is more than the total power consumption of many gliders.
A Trig TT-21 in a test righ being hammered with a high rate of
interrogations (similar to the rate used in the specs of the
transponder here) measured 325mA @ 12VDC. In practice owners of the
TT21 are seeing power consumption below 300mA. Richard this can't
possibly be right or the transponder will be utterly useless in
gliders - since you are planning on selling them what is the correct
power consumption at 12VDC.

3. They claim this is targeted at gliders and others uses, yet they
picked a mounting rectangular mount form factor pretty incompatible
with the standard 57mm hole (The Trig TT21 uses that hole or a smaller
rectangular cutout) the transponder mention here is a huge 1.78”H x
3.5”W (case dimension, panel cutout smaller).

---

Hang on, I feel it coming,...

WHAT THE !@#$? A $%^ DAMN BLOODY BOAT ANCHOR PIECE OF CRAP MODE C
TRANSPONDER!

(phew, now I fell better).

Why would any company in their right mind start building Mode C
transponders in the age of ADS-B data-out mandates in the USA? And
Mode S mandates in place already in Europe? Why would any purchaser in
their right mind purchase and install a Mode C transponder when the
Mode S Trig TT21 is available, is smaller, uses less power, is well
proven (good adoption esp. in gliders, used by the FAA for ADS-B
surveys, OEM'ed by Dynon, etc.) and provides a path to do 1090ES data-
out. Especially for the glider owners interested in a PowerFLARM the
Trig TT21 is currently by far the best option. There are other compact
affordable Mode S transponder options in Europe but none others
available in the USA at the current time. Maybe that will change over
time, competition is a nice thing.

The USA Mode C transponder market deserves to go away and die. If
(like me) you have one now it will keep working find and doing great
stuff for visibility to ATC and TCAS etc. for the foreseeable future
but it gives you no ADS-B data-out option. And specifically does not
give you 1090ES data-out that gives you direct long-range (much longer
then PowerFLARM-PowerFLARM) visibility to PowerFLARM receivers or
allow use with PowerFLARM for receiving ADS-R and TIS-B services.

There is absolutely space to argue that UAT devices can be used to do
ADS-B data-out to add to existing Mode C equipped aircraft (especially
for power aircraft to meet the 2020 carriage mandate) but I see no
justification for purchasing new Mode C transponders when there are
well priced and much more competitive Mode S transponders available
that provide that ADS-B data-out path (and in this case are much more
compact, easier to mount and appear to consume a lot less power).

Darryl

For two reasons: (1) it costs less to perform the biannual
inspection, and (2) you aren't broadcasting your tail number to the
Feds. Of course, you'll only get a 10 year life out of it...

-John

On Dec 8, 2:54 pm, Andy wrote:
Why would anyone buy a mode C transponder when for only a little more
one can buy a mode S unit?

Andy

On Dec 8, 12:03*pm, jcarlyle wrote:
For two reasons: *(1) it costs less to perform the biannual
inspection, and (2) you aren't broadcasting your tail number to the
Feds. Of course, you'll only get a 10 year life out of it...

-John

On Dec 8, 2:54 pm, Andy wrote:

Why would anyone buy a mode C transponder when for only a little more
one can buy a mode S unit?

Andy




Actually the 10 year life is not completely accurate, even if I agree
a bit with probably the sentiment behind it. I just don't want any
glider pilots with Mode C transponders to think their transponders
have an abslute hard limit where they stop being useful in 10 years.

Mode C transponders are usable it the USA well beyond 10 years - but
to meet the 2020 ADS-B data-out carriage requirement (a requirement
for power aircraft in similar airspace as transponders are required
now) you would need to add a UAT transmitter or replace the
transponder with a Mode S with 1090ES data-out. Right now its
impractical from a cost, STC paperwork hassle (on non-experimental)
and final -B rev compliance requirements on many products, to add ADS-
B data-out to most light aircraft or gliders but you can install a
Trig TT21 and in future update the firmware and add the ADS-B data-out
GPS.

How current aircraft owners manage the transition to the 2020 ADS-B
data-out mandate will be interesting to see - i.e. whether Mode C
equipped aircraft add UAT devices or swap out their transponders to
get new Mode S units with 1090ES data-out. I expect many will take the
transponder upgrade route since it is a chance to refresh older
transponders which they still need to carry (in may owner aircraft)
and older transponders can become a maintenance liability, so why not
refresh both in one box? For newer Mode C transponders there exists
more of an argument to add a UAT device. In the glider community in
the USA with PowerFLARM looking like important and popular technology
Mode S 1090ES data-out is a better technology to consider than UAT
data-out.

Darryl

On Dec 8, 1:03*pm, jcarlyle wrote:
For two reasons: *(1) it costs less to perform the biannual
inspection, and (2) you aren't broadcasting your tail number to the
Feds.

Ok, valid points.

I just checked with my local avionics shop. $95 for mode C and $125
for mode S. Not a deal breaker for me.

As to broadcasting the tail number - the TT21 installation menus
allow the aircraft ICAO code and the registration to be set but I
don't think there is an equipment requirement for them to be set. In
other words I think it will work if the defaults are left unchanged.
Is there any regulation that requires a mode S transponder to transmit
that data in US?

Andy

On Dec 8, 12:37*pm, Andy wrote:
On Dec 8, 1:03*pm, jcarlyle wrote:

For two reasons: *(1) it costs less to perform the biannual
inspection, and (2) you aren't broadcasting your tail number to the
Feds.

Ok, valid points.

I just checked with my local avionics shop. $95 for mode C and $125
for mode S. Not a deal breaker for me.

As to broadcasting the tail number *- the TT21 installation menus
allow the aircraft ICAO code and the registration to be set but I
don't think there is an equipment requirement for them to be set. *In
other words I think it will work if the defaults are left unchanged.
Is there any regulation that requires a mode S transponder to transmit
that data in US?

Andy

A Mode S transponder absolutely has to transmit the aircraft ICAO
address, a correctly configured ICAO address is required for the
transponder to actually work--bad things might happen if two aircraft
had the same default ICAO address were being interrogated at the same
time.

I am not sure where else this is captured in the regulations, but
checking this is a requirement at install and during the biannual
"Part 43 Appendix F" test.

Part 43 Appendix F...

(f) Mode S Address: Interrogate the Mode S transponder and verify that
it replies only to its assigned address. Use the correct address and
at least two incorrect addresses. The interrogations should be made at
a nominal rate of 50 interrogations per second.

---

I can't find it quickly in the regs but it may just be that the
requirement in 14CFR 91.215 (b) to operate in compliance with TSO
C-112 (which then captures you the pilot and not just the manufacturer
and that TSO's incorporation of RTCA DO-181 which may spell out the
Mode S address requirement). There better be an overriding
requirement, otherwise somebody could argue a pilot can can just
change it at any time. Yes its the off season but I'm not so bored yet
to fully follow this though.

Please be very careful here. Make sure your Mode S transponder is
using the correct ICAO address (the one registered to your aircraft).
If you really think you are goign to be doing bad things within view
of ATC then maybe you should rethink how you are flying.

Darryl

What Darryl said.

You might like to know that the avionics technician who did my VFR
transponder checks went to his computer and got the proper ICAO code
from the FAA. The reason is the "S" in Mode S stands for selective,
and they want to be darn sure ATC is broadcasting to the proper
aircraft.

I was being tongue in cheek with my previous post. There's no reason,
given the price and low power draw of the Trig TT21, that anyone
should even consider buying anything else right now (unless they're
replacing an existing transponder with the same type).

-John

On Dec 8, 3:37 pm, Andy wrote:
As to broadcasting the tail number - the TT21 installation menus
allow the aircraft ICAO code and the registration to be set but I
don't think there is an equipment requirement for them to be set. In
other words I think it will work if the defaults are left unchanged.
Is there any regulation that requires a mode S transponder to transmit
that data in US?