Transponder: Mode-C or Mode-S?

[Morteza Ansari]

I recently bought a new bird and need to put a transponder in it. The
choice was obvious (until I took a closer look). Trig TT21 seems like
a great choice: small footprint, built-in encoder, 1090ES ADS-B out,
and descent price. However a bit more looking revealed more questions
than answers. It seems it requires an ISO GPS and one could not use
typical GPS sources we have in gliders, it is not clear if the ADS-B
out work with PowerFLARM (at least from what I have heard), and the
biannual testing cost 2-3x as much as mode-C.

Any thoughts/suggestions from more knowledgable folks?


Cheers,
Morteza

[Darryl Ramm]

Morteza Ansari > wrote:
> I recently bought a new bird and need to put a transponder in it. The
> choice was obvious (until I took a closer look). Trig TT21 seems like
> a great choice: small footprint, built-in encoder, 1090ES ADS-B out,
> and descent price. However a bit more looking revealed more questions
> than answers. It seems it requires an ISO GPS and one could not use
> typical GPS sources we have in gliders, it is not clear if the ADS-B
> out work with PowerFLARM (at least from what I have heard), and the
> biannual testing cost 2-3x as much as mode-C.
>
> Any thoughts/suggestions from more knowledgable folks?
>
>
> Cheers,
> Morteza
>

The TT-21 as a Transponder utterly blows away any other transponder
available in the USA for use in gliders. it's power consumption, split
box install options, built in encoder, etc. are totally compelling by
themselves.

You should think of this as a Mode-S transponder today. That does not
use/need any GPS source. The 1090ES data-out capability is really there
for future use. And exactly what features/compliance you are aiming for
there is a longer discussion. You should think of ADS-B as a future
thing, not something here today. Many ADS-B devices require upgrades to
meet the 2020 mandate specs, and to meet this full spec (remember
gliders are exempt) you must use aviation (not consumer) style GPS
sources.

You cannot currently install any ADS-B data-out in any certified
aircraft including certified gliders without a STC approval, and since
the FAA is unlikely to grant an STC for an install with a non
Aviation/WAAS GPS that would today mean spending several $k to include
that GPS-and finding somebody to develop the STC. Those GPS prices will
fall in future and the STC requirement will go away. But if the FCC ever
allows a field approval install for a non-aviation GPS as a data-source
on a certified glider who knows (but don't hold your breath). This while
area is a mess at the moment and just not worth most glider pilots
losing sleep over.

Technically sophisticated folks who understand this stuff and who fly
experimental gliders today have other options including using
non-certified GPS sources. Setting this up is described in the Trig
manuals. If you are having to ask questions about this my inclination is
you should just install the TT-21 as a Mode-S transponder today.

I do not understand your specific concern about compatibility with
PowerFLARM. You need to clue us in to "what you have heard" if you want
cogent comment on that. PowerFLARM today will see/display other 1090ES
data-out equipped aircraft but will not provide an alarm for any threats
with those aircraft. That is coming in a future update. None of that is
specific to using a TT-21.

There are _very_ few 1090ES data-in equipped aircraft around right now
so this is not a big issue and other PowerFLARM equipped gliders will
see you via FLARM-FLARM anyhow. The basic Mode-S (or Mode-C) transponder
by contrast is seen by ATC, by TCAS which is widely used in airliners
and private jets, military transports, many tactical military aircraft
etc. and TCAD in some GA aircraft and by PCAS systems used widely in
lower end GA aircraft.

It is the 21st century buying a Mode C transponder makes _no_ sense. You
might be able to find a different test provider - not all uplift so
much for a Mode-S. There is no valid reason for such an inflated cost.
Some will do great deals to come to the gliderport/ramp and test a whole
fleet of gliders in one day.

Darryl

[John Smith]

Darryl Ramm wrote:
> The TT-21 as a Transponder utterly blows away any other transponder
> available in the USA for use in gliders.

Just be aware that the TT21 is a class 2 tansponder, i.e. not certified
for use above 15,000 feet, and therefore not suited for gliders. Buy the
TT22 instead which is class 1.

[jcarlyle]

Using the same logic, don't buy anything other than V rated tires for
your car, as the common S rating is only good for 112 mph (180 kph).

-John

On Sep 12, 7:55 am, John Smith > wrote:
> Just be aware that the TT21 is a class 2 tansponder, i.e. not certified
> for use above 15,000 feet, and therefore not suited for gliders. Buy the
> TT22 instead which is class 1.

[Darryl Ramm]

John Smith > wrote:
> Darryl Ramm wrote:
> > The TT-21 as a Transponder utterly blows away any other transponder
> > available in the USA for use in gliders.
>
> Just be aware that the TT21 is a class 2 tansponder, i.e. not
> certified for use above 15,000 feet, and therefore not suited for
> gliders. Buy the TT22 instead which is class 1.
>

This has been discussed here a lot before. the power difference will
make no practical difference. By all means pay slightly more and install
the TT22 but the important thing is for folks that fly in busy airspace
near airliners etc. to have a transponder (and even an older Mode C
transponder works fine fir that). Most transponders installed in gliders
in the USA appear to be class 2.

Darryl

[Stefan[_3_]]

Am 12.09.11 14:57, schrieb jcarlyle:
> Using the same logic, don't buy anything other than V rated tires for
> your car, as the common S rating is only good for 112 mph (180 kph).

If I wanted to drive with 112 mph (180 kph), then you'd be perfectly
correct. Glider pilots on the other hand tend to want to climb as high
as they can. In fact, the possibility to get a clearance to climb has
been the main reason for me to buy a transponder. So it would have been
pretty pointless to buy a class 2 transponder.

As always YMMV, but at least one should be aware of this limitation
before spending money on a class 2 transponder.

[jim wynhoff]

On Sep 12, 7:07*am, Stefan > wrote:
> Am 12.09.11 14:57, schrieb jcarlyle:
>
> > Using the same logic, don't buy anything other than V rated tires for
> > your car, as the common S rating is only good for 112 mph (180 kph).
>
> If I wanted to drive with 112 mph (180 kph), then you'd be perfectly
> correct. Glider pilots on the other hand tend to want to climb as high
> as they can. In fact, the possibility to get a clearance to climb has
> been the main reason for me to buy a transponder. So it would have been
> pretty pointless to buy a class 2 transponder.
>
> As always YMMV, but at least one should be aware of this limitation
> before spending money on a class 2 transponder.

Except for the fact that the folks on the ground that grant the
clearance don't know or care whether you've a Class 1 or Class 2
transmitter as long as they are receiving your signal. They also
don't care about you when you are more than 40 miles out, and if 135
watts won't get you 40 miles, something's wrong with your
installation. A properly installed* Class 2 with a dipole antenna in
a fiberglass (not carbon) fuselage glider will get more radiated power
out than most GA with metal fuselages and the 1/4 wave monopole
antenna they are forced to use. If you've got a carbon fuselage,
you're stuck with the 1/4 wave.
* a major contributor to lost outpout power is the cable from the
transceiver to the antenna. Don't use RG-58. It's unsuitable for L-
band.

[John Smith]

jim wynhoff wrote:
> Except for the fact that the folks on the ground that grant the
> clearance don't know or care whether you've a Class 1 or Class 2

The price of a TT22 vs TT21 is about $2500 vs $2300 (approx.). This $200
to $300 gap isn't nearly big enough for me to even start to think about
going the illegal route. As always YMMV.

[Eric Greenwell[_4_]]

On 9/12/2011 8:32 AM, John Smith wrote:
> jim wynhoff wrote:
>> Except for the fact that the folks on the ground that grant the
>> clearance don't know or care whether you've a Class 1 or Class 2
>
> The price of a TT22 vs TT21 is about $2500 vs $2300 (approx.). This $200
> to $300 gap isn't nearly big enough for me to even start to think about
> going the illegal route. As always YMMV.

What regulation makes it illegal for a glider to use the TT21 between
15,000 and 18,000'? Does it make a difference if the glider is licensed
"Experimental"?

Even if it is illegal, can we at least agree it is entirely suitable for
it's intended purpose: providing ATC and TCAS a glider's position and
altitude?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl

[JS]

Out of four different transponder and encoder combinations I've used
in gliders (Garmin/TransCal, Terra/Terra, 2x Becker/ACK, 2x Trig) the
Trig has proven to have the least power consumption.
The Trig is easy to install if you buy your own D-Sub connectors or
a crimp tool for the included ones, or have someone with a crimp tool
build the harness for you.
The small Trig control panel may fit in a corner of the panel you
thought unusable.
RG58 antenna cable worked fine for me (even with a TNC to BNC
adapter), but total cable length is less than 10' / 3m. For longer
runs you'll do better with something lower loss.
Joshua and Oakland have had no trouble getting radar contact with
the Trigs.
At the three avionics shops I called about Mode S, cost was the same
to certify Mode C or S transponders.
I believe the Trig takes less time if any adjustments are needed, but
in my experience they haven't required adjustment. The altimeter is
the most likely thing to require adjustment.
And it's Scottish, so it can't be crap!
Jim

[weersch[_2_]]

Hi Morteza
I have the Trig21.
Installed myself in my experimental to replace a Terra250.
Had no problem to get it signed-off at standard price at Precision
Static in Livermore.
Very happy with it.
Reno sees it very well, even at 18k. No issue with the output power.

When the PowerFlarm arrives, I suspect that suddenly there will be a
miraculous unexplained wire in my harness.
I guess that wire will be carrying 19200 baud NMEA sentences from the
PowerFlarm to the Trig21 and the Trig will be squittering 1080ES ADS-B
Out after someone accidentally toggled the setting in the setup menu
to enable this feature.
Of course I have nothing to do with this. I will stay legal.

I got a good price from Tim M. Better then mentioned above.

You can see my installation here:
https://sites.google.com/site/threeuniform/trig-tt21-transponder
Or you can have a look at my ship at Tahoe (or soon down the hill)

3U

[Darryl Ramm]

On 9/12/11 6:43 PM, weersch wrote:
>
> Hi Morteza
> I have the Trig21.
> Installed myself in my experimental to replace a Terra250.
> Had no problem to get it signed-off at standard price at Precision
> Static in Livermore.
> Very happy with it.
> Reno sees it very well, even at 18k. No issue with the output power.
>
> When the PowerFlarm arrives, I suspect that suddenly there will be a
> miraculous unexplained wire in my harness.
> I guess that wire will be carrying 19200 baud NMEA sentences from the
> PowerFlarm to the Trig21 and the Trig will be squittering 1080ES ADS-B
> Out after someone accidentally toggled the setting in the setup menu
> to enable this feature.
> Of course I have nothing to do with this. I will stay legal.
>
> I got a good price from Tim M. Better then mentioned above.
>
> You can see my installation here:
> https://sites.google.com/site/threeuniform/trig-tt21-transponder
> Or you can have a look at my ship at Tahoe (or soon down the hill)
>
> 3U

OK I think you fall into the "technically competent" subcategory (even
with the 1080ES typo) :-)

Darryl

[Morteza Ansari]

Thanks everyone for the feedback. I am convinced (again) that TT21 is
the best option. I will make sure I build the harness with the wires
for the GPS input and ADS-B out just in case. I will order one along
with the L2 antenna. I had great success with it in the previous
installation and they are so easy to install pretty much anywhere.

Now if I figure out what to do with the flight computer, I am all set
for redoing the panel layout and getting to work :)


Cheers,
Morteza

[weersch[_2_]]

>
> OK I think you fall into the "technically competent" subcategory (even
> with the 1080ES typo) :-)
>
> Darryl

Thanks Darryl for my induction in your hall of "technically
competent". I feel honored.
Yeah, doing too much 1080P work and not enough 1090ES.
3U

[Bruce Hoult]

On Sep 12, 11:55*pm, John Smith > wrote:
> Just be aware that the TT21 is a class 2 tansponder, i.e. not certified
> for use above 15,000 feet, and therefore not suited for gliders. Buy the
> TT22 instead which is class 1.

To date I've had 392 flights in gliders. I flew above 15,000 ft on a
flight on 17 Jan 1995 (in fact to 19,000 or so).

That's the ONLY time.

Most flights here don't go much above 5000 or 6000 ft. Even when
there's wave it's unusual to be able to get higher than maybe 12,000.

Your conditions are not the same as everyone's.

[Morteza Ansari]

On Sep 12, 11:17*pm, Bruce Hoult > wrote:
> On Sep 12, 11:55*pm, John Smith > wrote:
>
> > Just be aware that the TT21 is a class 2 tansponder, i.e. not certified
> > for use above 15,000 feet, and therefore not suited for gliders. Buy the
> > TT22 instead which is class 1.
>
> To date I've had 392 flights in gliders. I flew above 15,000 ft on a
> flight on 17 Jan 1995 (in fact to 19,000 or so).
>
> That's the ONLY time.
>
> Most flights here don't go much above 5000 or 6000 ft. Even when
> there's wave it's unusual to be able to get higher than maybe 12,000.
>
> Your conditions are not the same as everyone's.

I know what you mean. I had never gotten higher than 6K until I moved
to CA and started flying in the Sierras! Around here flying over 15K
is pretty routine. However, in my last glider I had a Becker 4401
which is also class 2 and I never had a problem. As a matter of fact
out of all the gliders in the Sierras, I would bet majority are using
class 2 transponders.


Cheers,
Morteza

[Andy[_10_]]

On Sep 12, 6:57*am, Darryl Ramm > wrote:
> John Smith > wrote:
> > Darryl Ramm wrote:
> > > The TT-21 as a Transponder utterly blows away any other transponder
> > > available in the USA for use in gliders.
>
> > Just be aware that the TT21 is a class 2 tansponder, i.e. not
> > certified for use above 15,000 feet, and therefore not suited for
> > gliders. Buy the TT22 instead which is class 1.
>
> This has been discussed here a lot before. the *power difference will
> make no practical difference. By all means pay slightly more and install
> the TT22 but the important thing is for folks that fly in busy airspace
> near airliners etc. to have a transponder (and even an older Mode C
> transponder works fine fir that). Most transponders installed in gliders
> in the USA appear to be class 2.
>
> Darryl

The TT22 draws about 20 percent more power when transmitting than the
TT21. It's not a lot, but with PowerFlarm going in to my panel as well
I will end up with a 1.5 amp total current requirement, so I figure
every milliamp is worth saving. It seems odd to me that Trig didn't
design with the Class A floor as the break point between design
specs. Then again...

9B

[JS]

When the panel became a power hog, Rex Mayes installed a 2-panel
Strobl Solar system.
On blue days it produces almost half the required current, a decent
battery extender.
But not very efficient under clouds.
Jim

On Sep 13, 1:24*am, Andy > wrote:

> The TT22 draws about 20 percent more power when transmitting than the
> TT21. It's not a lot, but with PowerFlarm going in to my panel as well
> I will end up with a 1.5 amp total current requirement, so I figure
> every milliamp is worth saving. It seems odd to me that Trig didn't
> design with the Class A floor as the break point between design
> specs. *Then again...
>
> 9B

[kd6veb]

Hi Gang
I had a Trig mode S transponder installed in my new Phoenix motor
glider. It appears to work fine as a mode C transponder. After
questioning NorCal while soaring they confirmed they could detect it
with their sqwark code, it would IDENT and so on - all the mode C
stuff. However most of the US including northern California/Nevada is
not yet set up for mode S so except for the future there is no reason
to have mode S in the US. Of course there are other reasons to have
mode S, probably the most important would be if you wanted to sell a
glider in Europe where mode S is becoming mandatory. For that market
having a mode S transponder will save the buyer about $2,500 - the
cost of replacing a mode C with a mode S transponder.
Dave

[Darryl Ramm]

Andy > wrote:

> The TT22 draws about 20 percent more power when transmitting than the
> TT21. It's not a lot, but with PowerFlarm going in to my panel as well
> I will end up with a 1.5 amp total current requirement, so I figure
> every milliamp is worth saving. It seems odd to me that Trig didn't
> design with the Class A floor as the break point between design
> specs. Then again...
>
> 9B
>

The 15,000 feet "limit" comes from wording in the relevant FAA TSO and
ultimately the RTCA standards. That the level was not set to FL180 is
kind of unfortunate. And I expect Trig folks would say the same thing.
But then this all goes back to days of traveling wave tubes and much
different technology and reliability/power output/cooling issues/cost
factors.

Darryl

[Eric Greenwell[_4_]]

On 9/13/2011 9:27 AM, kd6veb wrote:
> Hi Gang
> I had a Trig mode S transponder installed in my new Phoenix motor
> glider. It appears to work fine as a mode C transponder. After
> questioning NorCal while soaring they confirmed they could detect it
> with their sqwark code, it would IDENT and so on - all the mode C
> stuff. However most of the US including northern California/Nevada is
> not yet set up for mode S so except for the future there is no reason
> to have mode S in the US. Of course there are other reasons to have
> mode S, probably the most important would be if you wanted to sell a
> glider in Europe where mode S is becoming mandatory. For that market
> having a mode S transponder will save the buyer about $2,500 - the
> cost of replacing a mode C with a mode S transponder.
> Dave

A Trig Mode S unit is same cost as the comparable Becker when you add in
the cost of the encoder and harness the Becker requires, so there isn't
any financial reason to buy a Mode C transponder. The Trig has a much
lower current drain, making it the preferred choice anyway.

If you already have a Mode C, there probably isn't any reason to upgrade
now.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl

[Darryl Ramm]

On 9/13/11 9:27 AM, kd6veb wrote:
> Hi Gang
> I had a Trig mode S transponder installed in my new Phoenix motor
> glider. It appears to work fine as a mode C transponder. After
> questioning NorCal while soaring they confirmed they could detect it
> with their sqwark code, it would IDENT and so on - all the mode C
> stuff. However most of the US including northern California/Nevada is
> not yet set up for mode S so except for the future there is no reason
> to have mode S in the US. Of course there are other reasons to have
> mode S, probably the most important would be if you wanted to sell a
> glider in Europe where mode S is becoming mandatory. For that market
> having a mode S transponder will save the buyer about $2,500 - the
> cost of replacing a mode C with a mode S transponder.
> Dave

I think you may be confusing Mode-S and 1090ES data-out, or certainly
risk others confusing that.

The USA is well equipped with SSR Mode-S interrogators, all these
systems are also required to interrogate legacy Mode C transponders and
any Mode S transponder is also required to behave as a Mode-C
transponder if interrogated by a Mode-C only interrogator (Mode-S
interrogators have a way of locking out all Mode-S transponders from
seeing these legacy Mode-C interrogations).

In the USA when ATC sees your transponder return/squawk
code/altitude/ident from a Trig or other Mode-S transponder they are
likely seeing all that over Mode-S not Mode-A/C.

Mode-S transponders do have some benefits over Mode-C including a unique
ICAO ID (some folks may not think that is a benefit), better altitude
reporting (depends on the transponder), do not suffer from possible
congestion/correlation problems, optional Mode-S TIS traffic uplink (not
to be confused with TIS-B) at some USA sites (the Trig transponders do
support TIS), have ground/squat status switching, etc.. Those extra
things do *not* mean that a Mode-C transponder is not a great tool for
use near high traffic areas or that glider owners should upgrade from
Mode-C to Mode-S just to get these Mode-S improvements, but OTOH buying
a new Mode-C transponder nowadays makes no sense.

Mode-S is one thing (well actually many as its fairly complex overall
standard) and the ability to do 1090ES data-out is an option on top of
the data transmitter/extended squitter capability defined in the Mode-S
specs. Some older Mode-S transponders cannot do 1090ES data-out at all.
The ground infrastructure, products, regulations/interpretations to
support ADS-B/1090ES data-out is in it's early days as I tried to
explain earlier in this thread.

Darryl

[John Smith]

Eric Greenwell wrote:
> What regulation makes it illegal for a glider to use the TT21 between
> 15,000 and 18,000'?

Of course it's not illegal to turn on a class 2 transponder above 15,000
feet. But with a class 2 transponder, you can't tell ATC above 15,000
feet that you're transponder equipped, because legally, you're not.
Where I fly, I pretty routinely enter protected airspace at that
altitude, and I would hardly get a clearance without a transponder. This
has been the main reason for me to buy a transponder, so buying class 2
transponder would have been pretty pointless.

I don't care whether "they" would notice or not that I carry only a
class 2 transponder. The price gap of a mere $200 is far too small to
even consider to cheat.

Of course all depends on where you fly and to whom you want to sell your
glider later. So all I've wanted to say is that when you consider to buy
a class 2 transponder, be aware of the limitation.

[Darryl Ramm]

John Smith > wrote:
> Eric Greenwell wrote:
> > What regulation makes it illegal for a glider to use the TT21
> > between
> > 15,000 and 18,000'?
>
> Of course it's not illegal to turn on a class 2 transponder above
> 15,000 feet. But with a class 2 transponder, you can't tell ATC above
> 15,000 feet that you're transponder equipped,

Ah you want to show us a regulation or chain of regulations that says
that? Which country are you flying in? You keep using the word legal and
illegal etc. In the USA the FARs actually do not appear to place clear
requirements in this area on the PIC. Show us the regulations please...


And just for kicks 14CFR 91.215(c) "Transponder on operation" requires a
pilot say who climbs above 15,000' with a class 2 transponder to keep
operating that transponder.

> because legally, you're not. Where I fly, I pretty routinely enter
> protected airspace at that altitude, and I would hardly get a
> clearance without a transponder. This has been the main reason for me
> to buy a transponder, so buying class 2 transponder would have been
> pretty pointless.

And buying class 2 would likely have made no difference to any if that.

>
> I don't care whether "they" would notice or not that I carry only a
> class 2 transponder. The price gap of a mere $200 is far too small to
> even consider to cheat.
>
> Of course all depends on where you fly and to whom you want to sell
> your glider later. So all I've wanted to say is that when you consider
> to buy a class 2 transponder, be aware of the limitation.
>

and that's all fair but the more important thing is getting pilots in
key high traffic areas to equip and use transponders (of any class or
type)). And for most pilots in the USA it is not about clearances, it
is about avoiding an encounter with an airliner or fast jet.

Darryl

[ursus]

If you intend to use any smart PCAS (e.g. PowerFLARM) you want a Mode-
S, since suppressing your own transponder signal is a lot easier and
more reliable if the source is a Mode-S.
Other PCAS are also somewhat more likely to make sense of your
transmissions.
So do yourself and the World a favor and buy a Mode-S.

Ironically your decision is between buying into technology of the
fifties vs. the seventies...

Enjoy
Urs

[[email protected]]

On Sunday, September 11, 2011 at 11:54:26 PM UTC-4, Morteza Ansari wrote:
> I recently bought a new bird and need to put a transponder in it. The
> choice was obvious (until I took a closer look). Trig TT21 seems like
> a great choice: small footprint, built-in encoder, 1090ES ADS-B out,
> and descent price. However a bit more looking revealed more questions
> than answers. It seems it requires an ISO GPS and one could not use
> typical GPS sources we have in gliders, it is not clear if the ADS-B
> out work with PowerFLARM (at least from what I have heard), and the
> biannual testing cost 2-3x as much as mode-C.
>
> Any thoughts/suggestions from more knowledgable folks?
>
>
> Cheers,
> Morteza

==============

Not sure how you got your conclusions or that gobbledygook you just uttered..
I have been using the TT-21 for over 10 years and it is flawless. It and the TT-22 are identical except for the transmit power. I have no GPS hooked to it or anything else. It runs like a normal txpndr. I hooked it up in one afternoon, and as mentioned has been working perfectly.

[Paul Agnew]

You're responding to an eight year old thread. There is plenty of recent discussion that is more relevant.

PA

[Darryl Ramm]

On Tuesday, April 16, 2019 at 8:01:31 PM UTC-7, wrote:
> On Sunday, September 11, 2011 at 11:54:26 PM UTC-4, Morteza Ansari wrote:
> > I recently bought a new bird and need to put a transponder in it. The
> > choice was obvious (until I took a closer look). Trig TT21 seems like
> > a great choice: small footprint, built-in encoder, 1090ES ADS-B out,
> > and descent price. However a bit more looking revealed more questions
> > than answers. It seems it requires an ISO GPS and one could not use
> > typical GPS sources we have in gliders, it is not clear if the ADS-B
> > out work with PowerFLARM (at least from what I have heard), and the
> > biannual testing cost 2-3x as much as mode-C.
> >
> > Any thoughts/suggestions from more knowledgable folks?
> >
> >
> > Cheers,
> > Morteza
>
> ==============
>
> Not sure how you got your conclusions or that gobbledygook you just uttered.
> I have been using the TT-21 for over 10 years and it is flawless. It and the TT-22 are identical except for the transmit power. I have no GPS hooked to it or anything else. It runs like a normal txpndr. I hooked it up in one afternoon, and as mentioned has been working perfectly.

Welcome to r.a.s. This is an *excellent* first post.