GDL 82 Installation

avi8tor50 · #1 03-30-2018, 08:18 AM

I am seriously considering going the GDL 82 route for ADS-B. I have a GTX 327 with a standard Rami pole transponsder antenna. I would be purchasing the version that comes with the built-in GPS, For those of you that have already performed installation of the GDL 82 I have several questions:

1. Will my current transponder antenna be sufficient?
2. Was the installation difficult?
3. Did you have to replace the original coax wire running from the transponder
to the transponder antenna?
4. Where did you end up mounting the GPS antenna?
5. When you constructed the wiring harness which pins did you include? My
understanding is that I would not need the RS232 pins since I have no
devices to connect them to. Did you do squat and/or anonymous?
6. Did you perform the pre-installation output test for your original
transponder as recommended in the Garmin installation manual? If so,
did you have to have an avionics tech do this?

Any comments, tips, suggestions would be very much appreciated. It would be really wonderful if someone who has done this or is contemplating doing the installation would be willing to post a video or pics of the process and perhaps include some text for a step by step installation for those of us that follow.

As always, thanks to everyone who responded.

Peter K
9A-700 hrs

RVbySDI · #2 03-30-2018, 09:21 AM

Quote:

Originally Posted by avi8tor50

I am seriously considering going the GDL 82 route for ADS-B. I have a GTX 327 with a standard Rami pole transponsder antenna. I would be purchasing the version that comes with the built-in GPS, For those of you that have already performed installation of the GDL 82 I have several questions:

1. Will my current transponder antenna be sufficient? Yes
2. Was the installation difficult? No
3. Did you have to replace the original coax wire running from the transponder to the transponder antenna? No
4. Where did you end up mounting the GPS antenna? Mine is sitting on the dash just under the windshield and in front of the center brace bar. Works great there.
5. When you constructed the wiring harness which pins did you include? My
understanding is that I would not need the RS232 pins since I have no
devices to connect them to. Did you do squat and/or anonymous? Power, Ground, Anonymous switch, LED light. No squat switch.
6. Did you perform the pre-installation output test for your original
transponder as recommended in the Garmin installation manual? If so, did you have to have an avionics tech do this? No

Any comments, tips, suggestions would be very much appreciated. It would be really wonderful if someone who has done this or is contemplating doing the installation would be willing to post a video or pics of the process and perhaps include some text for a step by step installation for those of us that follow.

As always, thanks to everyone who responded.

Peter K
9A-700 hrs

Answers to your questions in RED above. The installation is not difficult at all. You do need to insert some pins into a DSub connector. You do have to either build a coax cable or purchase one with the correct connectors. All of that is straight forward WITH the right tools. Difficult WITHOUT the right tools. Make sure the coax is the correct minimum length (6.5 ft in my case, it can be coiled up and zip tied somewhere hidden if needed). It is my opinion this is the easiest install of any of the ADS-B OUT units out there.

Caveman · #3 03-30-2018, 12:22 PM

My installation is similar to Steve's except I mounted the GPS antenna to the fuselage top behind the tip up canopy and I did not wire up the optional LED. (It will be easy to do if I decide I want it later). I did do the frequency testing per the install manual.

Mine passed it's initial flight test and I have since requested two additional reports and they both came back fine. Its been flying about 2 months and has made at least 4 fairly long cross country trips.

All that said, a friend was talking to the avionics tech who does my transponder checks and when he found out I had successfully installed an 82 he got to questioning me about my ELT. I have an older AmeriKing AK-450 (Yes, the one with the AD). The avionics tech has been in contact with several other avionics shops and they are having trouble with the AK-450 + 82 installations and could hardly believe mine was working correctly when transmitting on the frequencies specified to be tested in the install manual. In fact they have never had an 82 pass these tests with and AK-450 in the plane. So, I stole the wife's laptop again and re-ran the tests specified, twice more following the manual very close. It still passed. I called the avionics guy back and he was finally convinced. I don't fully understand radio-ology, but apparently when the com transmits on frequencies near the GPS band, it can be picked up by the ELT antenna and somehow with the 450 it gets rebroadcast (probably the wrong terminology) in a manner that makes the 82 lose position which ATC frowns upon greatly. Perhaps Walt or Stein or Garmin has more info on this?

Anyway, something to consider for those installing in conjunction with an AK-450. Mine is working fine but apparently there are quite a few that aren't. I'm not sure what aircraft they were installing the 82's in that were giving them trouble. I'll likely upgrade to a new 406 ELT in the not too distant future.

94kb · #4 03-30-2018, 12:23 PM

1. Will my current transponder antenna be sufficient? Yes
2. Was the installation difficult? No
3. Did you have to replace the original coax wire running from the transponder to the
transponder antenna? No, Keep original RG58.
4. Where did you end up mounting the GPS antenna? Under the cowl.
5. When you constructed the wiring harness which pins did you include? My
understanding is that I would not need the RS232 pins since I have no
devices to connect them to. Did you do squat
and/or anonymous? Kit comes with very small pins for high density
connector. I had to buy a new positioner for my Daniels crimping
tool. I installed anonymous switch and failure indicator.
6. Did you perform the pre-installation output test for your original
transponder as recommended in the Garmin installation manual? If so,
did you have to have an avionics tech do this? No, No. but did check grounding with mili-ohm meter.

Installed in RV-4 with Garmin 327 xponder. FAA test had no problems. System works great.

RV-4 · #5 03-30-2018, 10:02 PM

''Installed in RV-4 with Garmin 327 xponder''

Kenneth,

Where about in your RV-4 did you install your GDL-82??

I'm planning to do the same in my -4 and wondering where I will mount the box as I running out of room ..

Thanks

Bruno
rv4@videotron.ca
P.S: If you have photos it is even better..

snopercod · #6 03-31-2018, 05:49 AM

From the GDL-82 Installation Manual:

Quote:

If a VHF COM transmitter causes problems with the GPS on selected frequencies, as listed in the post-installation checkout, the problem may be due to the ELT. To verify, disconnect the ELT antenna coax at the ELT unit. If the ELT is causing the problem, contact the ELT manufacturer or replace the ELT.

uk_figs · #7 03-31-2018, 05:54 AM

Quote:

Originally Posted by Caveman

, but apparently when the com transmits on frequencies near the GPS band, it can be picked up by the ELT antenna and somehow with the 450 it gets rebroadcast (probably the wrong terminology) in a manner that makes the 82 lose position which ATC frowns upon greatly. Perhaps Walt or Stein or Garmin has more info on this?

Joe
Is your ELT antenna in the tail like most of us?
Figs

wookiemail · #8 03-31-2018, 07:56 AM

I'm working on an GDL-82 in a Stinson. I am having a terrible time with VHF interference. It does have an AK-450 so I disconnected its antenna. I thought that should be enough. I wonder if a notch filter on these would help if they are the problem (and on other installs I've found the ELT is the difficulty on many).

Even with 3' spacing between VHF and GPS antenna I fail quickly when keying the emitter. I put a notch filter on the VHF antenna. KX-155.

I put an RG-400 6' extension cord on the GPS antenna so I could move it away from the aircraft. I need nearly 6' distance from the VHF antenna to get a pass.

The Stinson is big but I don't see how I can get separation like this.

Worst example of this I've ever seen. Others have caved easily.

BH

94kb · #9 03-31-2018, 08:59 AM

Bruno,
Here is a link to photos of install.

https://photos.app.goo.gl/IyAbQXVxt06qTzm93

Hope this works.
Ken

flightlogic · #10 03-31-2018, 09:24 AM

I have sat in a Stinson, but never installed avionics in one.... so my input here might be useless.
I know from experience that we always consider horizontal separation when spacing antennas. But the vertical can help too.
Placing one antenna directly above the offending transmit antenna, if possible... gives some additional immunity. It is done with repeater sites when a duplexer is not available.