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ADS-B failure with Trig system

Cloudboy

Active Member
The public reports show my ADS-B is failing NIC and NACp standards. I have Trig components: a Trig TT31 Transponder, a Trig TN72 GPS and Trig TA50 Antenna in an RV-3. The antenna is inside the engine cowl.
Does anyone have any suggestions about where to begin? I hate to just flounder around. An avionics shop told me the failed tests are GPS related. I emailed Trig customer service and asked if they have any advice. I haven't heard back yet.
 
Where exactly is your gps antenna mounted? I have a low opinion of antennas mounted in the engine compartment.
 
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I’ve recently battled the same errors, 100% the reason, gps antenna. I recommend you get the antenna out in the open . Simply put it on glare shield, or put it on top of cowl with velcro and fly. If NIC or NACp goes to 6 or or lower you’ll fail the papr report. In turns climbs and dives, if the antenna is blanketed long enough, seconds you can in Nic and NacP. Your antenna is weather proof per Trig.
 
Where exactly is your gps antenna mounted? I have a low opinion of antennas mounted in the engine compartment.
Agree 100%. The vast majority of these exact failures are due to antenna location with inside the cowl probably being the most common problem. That is unless you have a fiberglass airplane, which RVs are not.

:cool:
 
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The antenna is located on a small shelf projecting forward from the top of the firewall under the fiberglass cowl. I think your advice about moving the antenna is the next step to take and I will. I don't know how much extra cable I have. I'll try it temporarily on top of the glair shield with velcro If that works and there is enough cable I'll move the antenna to the top of the roll bar behind the pilot.
Does anyone have any experience with Trig customer support? I tried an email to their UK address a month ago and did not receive a reply. I called the Colorado company they listed as support for North America and found that they only did certification for the units and did not have operational advice. Now Trig lists Mid Continent as the North American source for support. Any experience with them?
 
You may want to check the GPS connector on the TN72, it’s difficult to install and easy to mess up. I see lots of cable/connector issues.
 
Antenna

I have my antenna behind the roll over triangle on a side opening canopy on my RV 3 and get excellent reception

I have A Trig radio and transponder, their support is very good.

Rob
G-BVDC
 
TT31

I have a tt-31 with garmin gps20a gps ant. mounted in the engine compartment. I had consulted with Stein before installing and was told that there are a lot of gps ant. installed in the engine compartment and they last and work just fine. I've not had any problems.
 
Settings

Make sure you have all the settings in the TT31 set correctly as this will cause a fail also. That is the easiest thing to check first.
 
The public reports show my ADS-B is failing NIC and NACp standards. I have Trig components: a Trig TT31 Transponder, a Trig TN72 GPS and Trig TA50 Antenna in an RV-3. The antenna is inside the engine cowl.
Does anyone have any suggestions about where to begin? I hate to just flounder around. An avionics shop told me the failed tests are GPS related. I emailed Trig customer service and asked if they have any advice. I haven't heard back yet.

I emailed Trig customer service and asked if they have any advice. I haven't heard back yet.[/QUOTE]


I have a Trig TT31 under the cowl of an RV8.

Had some problems. Turned out to be the coax cable/connector. Might be as simple as making sure everything is tight.

Same setup in the RV6. No problems.
 
I guess I better check the connections again, then temporarily mount the antenna on top of the glare shield and replace the wires from the GPS to the xpndr with a shielded twisted pair. Fingers crossed.
Thanks for the ideas.
 
.... and replace the wires from the GPS to the xpndr with a shielded twisted pair.
.

This is probably overkill for a short run, besides which the twisted pair part won't work. RS-232 lines use the common ground, so in general the 'twisted pair' won't have equal but opposite currents. Can't hurt, though, and shielding might be good, especially if it's a longer wire run.
 
Bob, Trig support agrees with you. I got in touch with them today and learned that my public report failure is caused by antenna location. Apparently the small puck antenna I have needs to be on top of a glare shield or similar location. Under the fiberglass cowl doesn't work well (as reported by others). If I insist on the under cowl location, the bigger antenna is necessary. It also costs about $400 more.
I'm waiting for the carb heat setup and a new airspeed indicator from Vans. When they get here, I'll change all three things at once and only remove the cowl once.
Thanks to everyone for the input.
 
Problem solved. As suggested by many, I moved the antenna to the top of the glare shield and flew. Passed with no errors. So, apparently the small cheaper Trig antenna is not reliable under the cowl and should be on top of the glare shield.
Thanks everyone for the help.
 
Good to hear there was a quick and easy fix.

I should have mentioned that my under the cowl antenna is one of the large (EX$PEN$IVE) ones that is required for the (IFR) Garmin 650 that feeds my TRIG.
 
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