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GDL 82 Installation

Richard,
I have had no issues. It passed the test on the first flight. I used RG-58 with very short runs between xponder-GDL82-antenna. Since the GPS antenna was so close, I had to loop the coax to get the required cable loss. I haven't had any issues with the 144 Mhz APRS transmission either - I am only running 100 mw.
Ken
 
I had issues with GPS signal loss on our community C150 after installing a GDL 82.

Installed one of these at the ELT end of the ELT antenna coax and all is well.

Part number is BLP-550+. $35 or so. Cheaper than a new ELT.
 
I installed the GDL82 with the provided harness. Powered up and tried to connect with the installation software and everything in filled in with “Unknown”. The laptop seems to know the GDL82 is there as it makes a sound when connecting/unconnecting the USB port. Also when launch the tool it has the “present” box checked on the start up screen. When I click the GDL82 box it puts up the connecting bar and only goes half way across before jumping to the “unit information” screen. Everything then filled out with “unknown” on all screens under Diagnostics tabs.

It’s either the USB on the harness is bad (I opened up the D-sub connector and verified wires a go to correct pins) or The GDL82 unit itself is bad.

I did find this thread and will be trying a shorter cable as I to am using a 16 ft Amazon Basics USB cable. I have 3 short 3-6 footers I will try today.

Anybody else have similar issues or any suggestions how to troubleshoot?

Update: Tried a 3 ft USB cable to attach my laptop and all worked great. The Installation manual says use less than 16 ft. The Amazon Basics 16 ft cable did not work for me but the 3 ft did.
 
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Just finished doing this in my 8A...

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, but mine was already RG400, I would have replaced it otherwise
4. Where did you end up mounting the GPS antenna? Top of the fuse behind the pax seat.
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? You will wire the serial pins to the provided USB receptical, which is used to configure the GDL82. I also wired the fault LED and anonymous switch, which also has a momentary down for testing the LED
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, although I had a transponder check done recently. Flew the day after my installation and my FAA performance test was 100% across the board

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

I just finished doing this and am happy with the results...

I made a shelf across the longerons just aft of the baggage area to mount the equipment. Mounted the L-Band antenna on the bottom skin adjacent to the next bulkhead aft, and the GPS antenna on the top of the fuselage just aft of the pax seat.

Everything powered up as expected and once the GDL 82 was configured everything was in the green. I recently removed the PSS AOA system that had an indicator mounted in the left side panel, so I made a little Switch/LED panel to put in place of the indicator. The LED is for GDL 82 faults, and the switch is a mini DPDT momentary down to test the LED, center off, and up on for anonymous mode. Worked out pretty good considering I'm working with existing holes. The next step in the upgrade process includes a GDU 460 and a new panel will be cut so I can finally clean everything up and make it all look pretty.

The GDL 50R is really nice. Hard wired to the Aera 600 for weather and traffic, and via Bluetooth to the iPad. The 660 also provides GPS to the 50R so no need for another antenna. The iPad is running ForeFlight and has BT connections to both the 660 for sending/receiving flight plans, and to the GDL50R for AHRS, weather and traffic. Works perfectly!

*Antenna considerations...Coax runs can be critical to the performance of the system:
The L-Band antenna should be as close as possible to the GDL82. (190-01810-00 GDL 82 TSO Installation Manual Rev. 5 Page 4-6)
The GPS antenna coax should be a minimum of 6.5' when using RG142B or RG400 to provide the correct db loss (if you're using something else you'll need to calculate it), And must also have a proper ground plane. (190-01810-00 GDL 82 TSO Installation Manual Rev. 5 Page 6-8)

Click for pics - https://photos.app.goo.gl/Nbj1VvCZE4XbzPhj8
 
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I put the GPS antenna that came with the GDL82 on a shelf attached to the firewall under the cowling. Works flawlessly. Not a difficult install
 
Click for pics
Nice looking installation! If it hasn't been mentioned before, the TED (ball and spike) transponder antennas are really marginal for the GDL-82. They're tuned for 1030-1090 Mhz transponder frequencies and performance is down quite a bit at 978 Mhz UAT frequency. I eventually changed mine out for a broadband (blade type) antenna from Delta Pop. I feel like performance is better with this one: http://www.deltapopaviation.com/Transponder_Antenna.html
 
Nice looking installation! If it hasn't been mentioned before, the TED (ball and spike) transponder antennas are really marginal for the GDL-82. They're tuned for 1030-1090 Mhz transponder frequencies and performance is down quite a bit at 978 Mhz UAT frequency. I eventually changed mine out for a broadband (blade type) antenna from Delta Pop. I feel like performance is better with this one: http://www.deltapopaviation.com/Transponder_Antenna.html

Correct. I decided to fly mine with the originally installed antenna, which looks like a Ted 104-12, and see how it performed. My performance flight netted a perfect report from the FAA, so for now I probably wont make any changes. I also happened to have a 104-12 in my parts bin from my panel building days so I decided to install that for my IN and it appears to work perfectly as well. Can you share how you determined better performance with the new antenna? I would like to conduct further tests on my installation to see if a change in the antenna would increase performance...Thanks!!
 
Can you share how you determined better performance with the new antenna?
Sure. I fly out of Asheville and we only have ONE ground station in the area and it's behind some low mountains. After I first installed the GDL-82 and would order up a PAPR, the "client percentage" was always in the 20% range. For those who don't know, if your aircraft isn't an ADS-B "client", the ground station won't send you TIS-B traffic. There were many times when I could see another aircraft visually and both of us were in radar coverage, but he didn't show up on my iPad. So I did two things: First, I changed out the Archer SA-005 dipole antenna for a Delta Pop for stronger transmissions on 978MHz, and Secondly, I installed an "external" ADS-B antenna (Actually a little J-pole antenna for stronger reception that I stuck on the inside of my rear window with suction cups) for my Stratus 2. My "client percentages" got better so I believe the blade type antenna helped. Maybe the external Stratus antenna helped, too, I dunno. (My plane is fiberglass so all other antennas are inside the airframe.)
 
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Ok cool, I'm in Colorado so I'm sure I can find some areas with obstructed towers and do some testing...Thanks! BTW...I have a cousin that lives in Asheville...beautiful there!


Sure. I fly out of Asheville and we only have ONE ground station in the area and it's behind some low mountains. After I first installed the GDL-82 and would order up a PAPR, the "client percentage" was always in the 20% range. For those who don't know, if your aircraft isn't an ADS-B "client", the ground station won't send you TIS-B traffic. There were many times when I could see another aircraft visually and both of us were in radar coverage, but he didn't show up on my iPad. So I did two things: First, I changed out the Archer SA-005 dipole antenna for a Delta Pop for stronger transmissions on 978MHz, and Secondly, I installed an "external" ADS-B antenna (Actually a little J-pole antenna for stronger reception that I stuck on the inside of my rear window with suction cups) for my Stratus 2. My "client percentages" got better so I believe the blade type antenna helped. Maybe the external Stratus antenna helped, too, I dunno. (My plane is fiberglass so all other antennas are inside the airframe.)
 
I just finished doing this and am happy with the results...


*Antenna considerations...Coax runs can be critical to the performance of the system:
The L-Band antenna should be as close as possible to the GDL82. (190-01810-00 GDL 82 TSO Installation Manual Rev. 5 Page 4-6)


Click for pics - https://photos.app.goo.gl/Nbj1VvCZE4XbzPhj8


How close is "close", I wonder?

I was planning on putting the GDL 82 on the after side of an access door located at the after bulkhead of the forward baggage compartment (lots of fore and afts, I know). The present L-band is below that and a little to the left so I'd estimate the coax run to be about 2 feet.

"And must also have a proper ground plane. (190-01810-00 GDL 82 TSO Installation Manual Rev. 5 Page 6-8)"

I was thinking of locating the GPS antenna where you put it - just aft of the PX seat. What did you do to assure a proper ground plane?

Thanks! I'm just looking to gather as much info as I can before I start this operation.
 
How close is "close", I wonder?

I was planning on putting the GDL 82 on the after side of an access door located at the after bulkhead of the forward baggage compartment (lots of fore and afts, I know). The present L-band is below that and a little to the left so I'd estimate the coax run to be about 2 feet.

"And must also have a proper ground plane. (190-01810-00 GDL 82 TSO Installation Manual Rev. 5 Page 6-8)"

I was thinking of locating the GPS antenna where you put it - just aft of the PX seat. What did you do to assure a proper ground plane?

Thanks! I'm just looking to gather as much info as I can before I start this operation.

On my -8 I mounted the GDL-82 in the pax compartment inside the right side panel covering the flap control rods. Mounted the antenna in the same place as depicted the above photo cept I put a wedge under it to keep it level. A reinforcement/ground plane was added to the backbone skin inside the baggage compartment. The 6.5' of coax was run straight aft, thru the baggage compartment along a stringer then forward to the antenna. I hate exposed cables/wires.
 
How close is "close", I wonder?

I was planning on putting the GDL 82 on the after side of an access door located at the after bulkhead of the forward baggage compartment (lots of fore and afts, I know). The present L-band is below that and a little to the left so I'd estimate the coax run to be about 2 feet.

"And must also have a proper ground plane. (190-01810-00 GDL 82 TSO Installation Manual Rev. 5 Page 6-8)"

I was thinking of locating the GPS antenna where you put it - just aft of the PX seat. What did you do to assure a proper ground plane?

Thanks! I'm just looking to gather as much info as I can before I start this operation.

My GDL82 is mounted 2? above the L band TED antenna. Coax is 8? long. Longer then needed but wanted large bend radius and some length for easy install/remove
 
Not sure if this has been addressed elsewhere, but just in case - here is the reason for the GPS signal loss with some COM transmission frequencies, and what you can do about it. It was noted in this thread as a problem with AK-450 ELTs in particular, but can occur with other ELTs as well.

When you COM transmit, the signal is received by the ELT antenna. The transmit output section of an ELT invariably has some non-linear characteristics resulting from the semiconductor components of the output stage. This non-linearity will create odd harmonic components of the received signal, and re-transmit them passively. It just so happens that the odd harmonics (multiples) of several COM frequencies fall right into the GPS band, and since GPS signals are so weak, a fairly low level signal like this can interfere. The particular frequencies are listed in the GPS installation test section. This happens only with the ELT because of it's specific operating frequency and antenna.

A very simple fix is a GPS frequency 1575.42MHz trap filter put in series with the ELT output, right at the ELT. These are available for purchase, or you can make one for yourself with a simple BNC T connector for very low cost. Two sides of the connector are to the ELT and antenna, and the third has a short coax open stub, which acts as the trap/filter. This can be made with the help of a spectrum analyzer with a tracking generator where you progressively cut the stub until the filter notch is at 1575MHz. The length is quite short, and approaching the finish length will involve filing or grinding, rather than just snipping. If there is any interest, I can supply a picture of mine.

Reinhard Metz

Hi all,

I have the dreaded AK450.

My GPS antenna is mounted on the top of the fuselage a little behind the passenger seat. So I know I have enough coax between the GPS antenna and the GDL 82.

So today, when I went to test my GDL 82 installation it passed every test but the "transmit at these frequencies for 35 seconds" tests. It would occasionally pass a frequency test but more often than not, it lost all GPS contacts. Release the mike button and the GPS satellites came back.

I've seen this solution in this thread:


"Part number is BLP-550+. $35 or so."

And this general solution in the above quote:

"A very simple fix is a GPS frequency 1575.42MHz trap filter put in series with the ELT output, right at the ELT. "

Not an electronics wizard so I won't be making a trap filter so I have some questions:

1) Is the BLP-550 = to a 1575.42MHz trap filter?

2) The writer in the quote above say that these are "readily available...can anyone suggest a vendor/model number ?

Thanks
 
ELT

You should only need it on the ELT. The instructions are for comm radios, but they apply to the ELT as well since the ELT uses a comm frequency. There’s something about that particular ELT that sends out harmonics disruptive to the GPS.

-Andy
 
Has anyone had problems with the Garmin GLD 82 install/configuration program where it would connect to the GDL 82, display the unit info correctly, and then disconnect a second or two later?


Ok so I installed one of these:

https://www.aircraftspruce.com/catal...ickkey=7401549

On my ELT antenna and that seemed to solve the problem of losing the GPS 3D fix

When I ran these ground tests I used a big heavy Desktop computer running Windows 10, a keyboard, mouse and monitor. The Garmin install tool worked fine. I configured the GDL 82 and tested the configuration.

But that's too klunky and I don't want to lug all that stuff to the airport every time I need to do an upgrade or check the system.

So I bought an ACER laptop running W10.

Today I installed the GDL install/configuration tool, and ran it.

I get this at the start:

Present.png


So the laptop sees the device. I can sit there all day long and nothing changed on this window - the device stays present.

Then I click on GDL 82 and go to the Unit Information page:

Connected_Unit_Info.png


It sees the correct data.

But that lasted only about 1 second and then it disconnects and I get this:

Disconnected_Unit_Info.png


If I unplug the USB port and plug it back in, the data comes up again as connected but then it disconnects within a second or two.

I can't tell if the GDL 82 is the problem or something about the laptop.

I shut off all firewalls, disconnected from the internet, shut off Norton entirely, turned off everything I thought might interfere.

No change.

Has anyone seen this before? Is there some problem with hooking up a different computer to the GDL 82 than the one it was configured with?
 
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Has anyone had problems with the Garmin GLD 82 install/configuration program where it would connect to the GDL 82, display the unit info correctly, and then disconnect a second or two later?

Saville,

You might read this posting about maximum USB cable length in case you are using a cable longer than 1 meter.

Steve
 
Saville,

You might read this posting about maximum USB cable length in case you are using a cable longer than 1 meter.

Steve

Well I'm using the USB cable provided to me by ACSpruce.

It worked fine with the Desktop computer.

It's probably slightly over one meter but far shorter than the max length specified by Garmin.

Thanks
 
Is there some problem with hooking up a different computer to the GDL 82 than the one it was configured with?

No, there is no problem with using different computers for configuration and software changes.

I have used several different Dell Win10 laptops, and never had a problem.

Steve
 
Problem solved

So I decided to take the cable from my printer and use that with the laptop and GDL 82 and see if that worked any better.

Rock solid.,

It was the cable after all.

Thanks to all who helped.

My ADS-B install and ground checkout is successfully completed.

Next - Flight Test.
 
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