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Joined: 14 Aug 2013
Posts: 5
Location: Pullman, WA

PostPosted: Thu Jul 18, 2019 7:40 am    Post subject: GDL-82 Reply with quote

I know it might not be the best or cheapest solution, but I have a GDL-82 and I'm guessing a few other Maule pilots have installed one as well.

Wondering if anyone has any pictures of where they mounted it or even a description.
Working with my A&P and we're knocking a few ideas around. Thought I'd see what others experience has been.


Eric Stratte
M7-260 N260BD
Based at WN26
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Joined: 23 Oct 2013
Posts: 415
Location: CO

PostPosted: Thu Jul 25, 2019 4:28 am    Post subject: Reply with quote

I'm thinking about one of those too. Please share your total costs once you are done.
1980 M5-235
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PostPosted: Mon Dec 23, 2019 12:25 pm    Post subject: Reply with quote

What a great learning experience this ADS-B thing has become. Thought I'd update this 6 month old post, as I just went through removing my Tailbeacon and installing a GDL-82. I pushed the plane out to go through the ground checks on the GDL-82, and everything checked out perfect, until the comm radio interference test. Keying the mic on either of my Narco MK12E comm radios obliterated the GPS signal across the board instantaneously on all 12 comm frequencies specified in the installation manual. It's a 12th and 13th harmonic problem from the comm antennas, and can be magnified by older ELT units. Some avionics techs claim ELT replacement is the most successful way to resolve the problem, as even a turned off 121.5 ELT can apparently resonate a harmonic from its antenna that obscures the GPS signal.

Next step was to take the ELT out of the plane and retest. That made no difference, so I got a couple of notch filters ordered from Spruce. The Garmin filter was significantly cheaper than the TED version also available from Spruce, but only one was in stock at the time so I ordered a TED version as well. The Garmin version is manufactured by Telegartner in Germany, and worked OK on my Comm1 radio but not on Comm2. I was thrilled to find that the TED unit worked perfectly on Comm2, whose antenna is actually farther away from the GA35 gps antenna (5 feet vs. 3 feet). My new Garmin GPS antenna is placed where Maule recommends on their drawing, already over three feet from the nearest comm or ELT antenna.

Narco radios have a reputation of not playing as well with gps units as newer radios. WAAS GPS units are also more sensitive to that than non-WAAS. Fortunately, using the notch filters on just the Comm radios worked for me, and I passed the first PAPR validation flight with 0% failures. I went through seven failed validation flights with the tailbeacon before I exchanged it for the Garmin unit.

Here's a picture of where I installed the GDL-82, I used cushioned Adel clamps on the fuselage tubing behind the copilot's kickpanel. That put it close to the transponder antenna. I used a 10 ft TNC cable for the GPS antenna and a 3 ft BNC cable for the transponder antenna. My hangar mate already had a Daniels crimper so I just had to invest in a K42 insert for it.

Sorry if the image is sideways, right click it to open it in a new tab and it will display correctly.
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