Trig TN72 Antenna [Archive]

Andrew Ainslie

April 3rd 17, 03:26 PM

Greetings all,

Well, the TN72 is to be released shortly, and for those of us with Trig transponders this looks to be a great way to get ADS-B compliant. But... they recommend also buying a phenomenally expensive $300 plus antenna with it. Basically, it's this antenna here:

http://www.aircraftspruce.com/catalog/avpages/rami11-14354.php

I see why it's $300 - after all, it contains an amplifier and yet can handles being exposed to god knows what placed on the outside of an aircraft. But we will no doubt be placing ours somewhere inside where they never get wet. So is there any reason why one can't sue this one?

https://www.amazon.com/Waterproof-Active-Antenna-28dB-Gain/dp/B00LXRQY9A/ref=sr_1_3?ie=UTF8&qid=1491225920&sr=8-3&keywords=GPS+antenna+%2B5V

Both use the +5V to run a 28dB gain amp built into the unit. Not sure I want to spend $300 when I can spend $14! Possible issues are 1) technical and 2) regulatory, and I thought I'd test the knowledge on this board to see if I can't save a few sheckels.

BTW this could affect quite a few of us, so I'm really hoping that people with a good avionics/GPS level of knowledge could help us out here.

Richard[_15_]

April 3rd 17, 03:47 PM

On Monday, April 3, 2017 at 7:27:03 AM UTC-7, Andrew Ainslie wrote:
> Greetings all,
>
> Well, the TN72 is to be released shortly, and for those of us with Trig transponders this looks to be a great way to get ADS-B compliant. But... they recommend also buying a phenomenally expensive $300 plus antenna with it. Basically, it's this antenna here:
>
> http://www.aircraftspruce.com/catalog/avpages/rami11-14354.php
>
> I see why it's $300 - after all, it contains an amplifier and yet can handles being exposed to god knows what placed on the outside of an aircraft. But we will no doubt be placing ours somewhere inside where they never get wet. So is there any reason why one can't sue this one?
>
> https://www.amazon.com/Waterproof-Active-Antenna-28dB-Gain/dp/B00LXRQY9A/ref=sr_1_3?ie=UTF8&qid=1491225920&sr=8-3&keywords=GPS+antenna+%2B5V
>
> Both use the +5V to run a 28dB gain amp built into the unit. Not sure I want to spend $300 when I can spend $14! Possible issues are 1) technical and 2) regulatory, and I thought I'd test the knowledge on this board to see if I can't save a few sheckels.
>
> BTW this could affect quite a few of us, so I'm really hoping that people with a good avionics/GPS level of knowledge could help us out here.

The TN72 antenna is different that the amazon antenna. The TN72 is an amplified TSO antenna that is why the size and price is more.

Richard
www.craggyaero.com

Andrew Ainslie

April 3rd 17, 03:51 PM

Richard,

That antenna is also amplified. I get that the TRIG one is TSO'ed, but is that really necessary for this application? Also a lot of money was spent making it tough to go on top of a plane in the breeze, which we don't need.

Andrew Ainslie

April 3rd 17, 04:16 PM

I just noticed that there is a difference in cable termination, which could probably be fixed with something like this:

https://www.amazon.com/2pack-Female-Jack-F-Male-Plug-M-adapter-connector/dp/B00ZXPMHX0/ref=sr_1_11?s=electronics&ie=UTF8&qid=1491232372&sr=1-11&keywords=TNC+SMA+cable

GeneReinecke

April 3rd 17, 04:42 PM

On Monday, April 3, 2017 at 8:27:03 AM UTC-6, Andrew Ainslie wrote:
> Greetings all,
>
> Well, the TN72 is to be released shortly, and for those of us with Trig transponders this looks to be a great way to get ADS-B compliant. But... they recommend also buying a phenomenally expensive $300 plus antenna with it. Basically, it's this antenna here:
>
> http://www.aircraftspruce.com/catalog/avpages/rami11-14354.php
>
> I see why it's $300 - after all, it contains an amplifier and yet can handles being exposed to god knows what placed on the outside of an aircraft. But we will no doubt be placing ours somewhere inside where they never get wet. So is there any reason why one can't sue this one?
>
> https://www.amazon.com/Waterproof-Active-Antenna-28dB-Gain/dp/B00LXRQY9A/ref=sr_1_3?ie=UTF8&qid=1491225920&sr=8-3&keywords=GPS+antenna+%2B5V
>
> Both use the +5V to run a 28dB gain amp built into the unit. Not sure I want to spend $300 when I can spend $14! Possible issues are 1) technical and 2) regulatory, and I thought I'd test the knowledge on this board to see if I can't save a few sheckels.
>
> BTW this could affect quite a few of us, so I'm really hoping that people with a good avionics/GPS level of knowledge could help us out here.

Pardon the thread creep: Will this work with a Trig 21 Transponder in an experimental glider or do I need a Trig 22 or better? $359 at Aircraft Spruce plus a $300 antenna is a pretty affordable option for ADS B voluntary compliance. I guess worries about multi thousand dollar solutions was overhyped?

Renny[_2_]

April 3rd 17, 04:49 PM

On Monday, April 3, 2017 at 9:42:32 AM UTC-6, GeneReinecke wrote:
> On Monday, April 3, 2017 at 8:27:03 AM UTC-6, Andrew Ainslie wrote:
> > Greetings all,
> >
> > Well, the TN72 is to be released shortly, and for those of us with Trig transponders this looks to be a great way to get ADS-B compliant. But... they recommend also buying a phenomenally expensive $300 plus antenna with it. Basically, it's this antenna here:
> >
> > http://www.aircraftspruce.com/catalog/avpages/rami11-14354.php
> >
> > I see why it's $300 - after all, it contains an amplifier and yet can handles being exposed to god knows what placed on the outside of an aircraft.. But we will no doubt be placing ours somewhere inside where they never get wet. So is there any reason why one can't sue this one?
> >
> > https://www.amazon.com/Waterproof-Active-Antenna-28dB-Gain/dp/B00LXRQY9A/ref=sr_1_3?ie=UTF8&qid=1491225920&sr=8-3&keywords=GPS+antenna+%2B5V
> >
> > Both use the +5V to run a 28dB gain amp built into the unit. Not sure I want to spend $300 when I can spend $14! Possible issues are 1) technical and 2) regulatory, and I thought I'd test the knowledge on this board to see if I can't save a few sheckels.
> >
> > BTW this could affect quite a few of us, so I'm really hoping that people with a good avionics/GPS level of knowledge could help us out here.
>
> Pardon the thread creep: Will this work with a Trig 21 Transponder in an experimental glider or do I need a Trig 22 or better? $359 at Aircraft Spruce plus a $300 antenna is a pretty affordable option for ADS B voluntary compliance. I guess worries about multi thousand dollar solutions was overhyped?

Gene,
I checked on this question for an "experimental" glider and on Dec 7th, 2016 I received this reply directly from Trig:

"Thank you for your interest in our TN72 GPS receiver.

The TN72 is compatible with your TT21 transponder and is an ideal choice for your glider.
TABS exists to allow exempt aircraft like yours to participate in ADS-B.
Your TT21 transponder exceeds the technical requirements of TABS and so does not require upgrading."

Thx - Renny

GeneReinecke

April 3rd 17, 10:49 PM

Richard[_15_]

April 4th 17, 04:05 AM

On Monday, April 3, 2017 at 8:42:32 AM UTC-7, GeneReinecke wrote:
> On Monday, April 3, 2017 at 8:27:03 AM UTC-6, Andrew Ainslie wrote:
> > Greetings all,
> >
> > Well, the TN72 is to be released shortly, and for those of us with Trig transponders this looks to be a great way to get ADS-B compliant. But... they recommend also buying a phenomenally expensive $300 plus antenna with it. Basically, it's this antenna here:
> >
> > http://www.aircraftspruce.com/catalog/avpages/rami11-14354.php
> >
> > I see why it's $300 - after all, it contains an amplifier and yet can handles being exposed to god knows what placed on the outside of an aircraft.. But we will no doubt be placing ours somewhere inside where they never get wet. So is there any reason why one can't sue this one?
> >
> > https://www.amazon.com/Waterproof-Active-Antenna-28dB-Gain/dp/B00LXRQY9A/ref=sr_1_3?ie=UTF8&qid=1491225920&sr=8-3&keywords=GPS+antenna+%2B5V
> >
> > Both use the +5V to run a 28dB gain amp built into the unit. Not sure I want to spend $300 when I can spend $14! Possible issues are 1) technical and 2) regulatory, and I thought I'd test the knowledge on this board to see if I can't save a few sheckels.
> >
> > BTW this could affect quite a few of us, so I'm really hoping that people with a good avionics/GPS level of knowledge could help us out here.
>
> Pardon the thread creep: Will this work with a Trig 21 Transponder in an experimental glider or do I need a Trig 22 or better? $359 at Aircraft Spruce plus a $300 antenna is a pretty affordable option for ADS B voluntary compliance. I guess worries about multi thousand dollar solutions was overhyped?

More affordable

http://www.craggyaero.com/trig.htm

Richard
Craggy Aero

son_of_flubber

April 5th 17, 01:55 AM

The previous owner of my glider installed a TT21. Last July in rural Vermont, a Cessna overflew me on my 6. He was about 100 feet above me.

So I've been thinking that there is a very remote chance that installing ADS-B out might one day be a very big one time pay off for me. I expect that as we get closer to 2020, more and more ADS-B equipped power pilots will rely more and more on their screens and audible alerts for VFR traffic avoidance. I'll probably install ADS-B out eventually, and the cost of the TN72 with the recommended antenna seems reasonable. So the question remains, do I want to spend $300 less and buy a no-name antenna on Amazon?

On Monday, April 3, 2017 at 10:27:03 AM UTC-4, Andrew Ainslie wrote:
> a phenomenally expensive $300 plus antenna with it....
>
> I see why it's $300 - after all, it contains an amplifier and yet can handles being exposed to god knows what placed on the outside of an aircraft. But we will no doubt be placing ours somewhere inside where they never get wet. So is there any reason why one can't use this one?

This is missing the point. The TSO'd antenna is tested to comply with the specification. I'd be paying $300 for a quality assurance process and some peace of mind. The price is set by what the buyers will pay, it has little to do with the cost of production. The $300 would seem insignificant if I were paying $6000 to install ADS-B in my aircraft.

The seller of the bargain antenna copied the much sought-after-specification onto the Amazon catalog. He knows a guy, that knows a guy, who makes cheap antennas. Maybe the antenna unit that I buy off Amazon will work as advertised, and maybe it will still be working when I need it. Maybe it will develop a short and brick my TN72. Maybe I will notice and install a new TN72 and an expensive antenna before I really need it. It's all a matter of probabilities. If I'm feeling lucky, then why bother installing ADS-B at all?

Andrew Ainslie

April 5th 17, 01:24 PM

I'm now a lot more into this. Your Clearnav, LXNAV, FLARM antennae are all exactly the same as that 300 buck antenna in terms of spec and performance.

BTW if you're really into TSO'ed equipment, don't buy the $350 TN 72, but the $2000 TN70, which is functionally almost exactly the same... but TSO'ed.

Your choice!

son_of_flubber

April 5th 17, 02:22 PM

On Wednesday, April 5, 2017 at 8:24:12 AM UTC-4, Andrew Ainslie wrote:
> Your Clearnav, LXNAV, FLARM antennae are all exactly the same as that 300 buck antenna in terms of spec and performance.

And maybe the actual performance of a bargain antenna matches the advertised performance.

Andrew Ainslie

April 5th 17, 04:45 PM

If the antenna doesn't perform adequately one would know pretty quickly. It simply wouldn't be able to pinpoint location accurately.

Plus, that antenna was just an example. Clearnav sells a similar one for about $40. I'm busy fitting an antenna sharing box for my clearnavs and Flarm so I'll have a couple spare. And I've never heard of anyone finding those unsatisfactory, other than occasional location related problems.

Ignoring quality differences, are there technical or FAR related reasons not to do this?

[email protected]

April 5th 17, 07:35 PM

Thanks for pointing out these lower-cost antennas. I see the Amazon antenna has a magnet in the base: that would make it unacceptable to me, since it will be near my compass, unless the magnet can be removed.

I've never been able to understand the FAA regulations about TSO components.. But have been told by several mechanics that its legal to use non-TSO components in an experimental glider. An adsb installation will need to be certified before use, and every two years, and you can also request an inflight test from ATC.

Dan Marotta

April 5th 17, 08:12 PM

I just opened a GPS antenna to shorten the cable. Why they're sold with
a 10 meter (!) cable is beyond me, however, after peeling off the
sticker on the bottom, you'll see two magnets held in place with
screws. Simply remove the screws and remove the magnets.

BTW, my GPS antenna cable is now less than 12 inches long, has no
magnets, and works just fine.

On 4/5/2017 12:35 PM, wrote:
> Thanks for pointing out these lower-cost antennas. I see the Amazon antenna has a magnet in the base: that would make it unacceptable to me, since it will be near my compass, unless the magnet can be removed.
>
> I've never been able to understand the FAA regulations about TSO components. But have been told by several mechanics that its legal to use non-TSO components in an experimental glider. An adsb installation will need to be certified before use, and every two years, and you can also request an inflight test from ATC.

--
Dan, 5J

son_of_flubber

April 6th 17, 12:55 AM

On Wednesday, April 5, 2017 at 11:45:07 AM UTC-4, Andrew Ainslie wrote:

>I'm busy fitting an antenna sharing box for my clearnavs and Flarm so I'll have a couple spare.

Can you hook up two of the cheaper antennas to your antenna sharing box and gain reliability via redundancy?

Sharing one antenna between multiple GPS reliant devices creates a single point of failure.

Richard[_15_]

April 6th 17, 01:13 AM

On Wednesday, April 5, 2017 at 4:55:52 PM UTC-7, son_of_flubber wrote:
> On Wednesday, April 5, 2017 at 11:45:07 AM UTC-4, Andrew Ainslie wrote:
>
> >I'm busy fitting an antenna sharing box for my clearnavs and Flarm so I'll have a couple spare.
>
> Can you hook up two of the cheaper antennas to your antenna sharing box and gain reliability via redundancy?
>
> Sharing one antenna between multiple GPS reliant devices creates a single point of failure.

It also presents a voltage problem unless you use a dc blocker on one of the antennas.

Richard
www.craggyaero.com

Andrew Ainslie

April 6th 17, 01:38 AM

There's another thread on this:

https://groups.google.com/forum/m/#!searchin/rec.aviation.soaring/Multiple$20GPS$20antennas/rec.aviation.soaring/ovwxmlKN3Iw

This can help with the quality of reception, admittedly at a mild chance of loss of redundancy should the antenna self destruct mid flight. I can't recall ever hearing of such a case.

My intent is to share an antenna amongst FLARM and 2 Clearnav boxes using the divider described in that post and run the TN72 off a separate antenna located further back in the glider, away from the shared one to minimize RF interference.

April 6th 17, 04:21 AM

On Wednesday, April 5, 2017 at 4:55:52 PM UTC-7, son_of_flubber wrote:
> On Wednesday, April 5, 2017 at 11:45:07 AM UTC-4, Andrew Ainslie wrote:
>
> >I'm busy fitting an antenna sharing box for my clearnavs and Flarm so I'll have a couple spare.
>
> Can you hook up two of the cheaper antennas to your antenna sharing box and gain reliability via redundancy?
>
> Sharing one antenna between multiple GPS reliant devices creates a single point of failure.

Flub:
For the first situation you would need to have a GPS receiver capable of diversity reception. It would have an A and B antenna connection on the receiver. Doubt one exists.
I've only been using a divider for a couple of years, but yet to have the failure you mention.
Using a 12 volt GPS antenna eliminates the need for DC blockers.
Jim