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09-15-2014, 01:34 PM
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Join Date: Mar 2012
Location: San Diego, CA
Posts: 133
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Archer NAV issues....
I realize this have been brought up many times here on the forums, but I still havent found my smoking gun for my bad Glideslope reception. Everything is routed as per instructions. My ground is alu tape on the tip and on the wing, though nutplates. LOC works fine, but of course it is a different frequency.
First thing that comes to mind is if the alu tape provides enough ground? I could put in copper or add a separate ground strap....?
I also have strobes and HD led landing lights. Can there be an EMI issue?
All of you who had this problem, how did you solve it?
If the coax was bad, then I wouldnt have LOC and VOR reception either right?
It is not that I dont have glideslope reception, but I only get it very close to the airports, and I have tried a few airports and the result is the same. It is about 1-2 miles out at the most...
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09-15-2014, 02:02 PM
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Join Date: Sep 2011
Location: Edgewater, FL. KSFB
Posts: 1,118
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I think it depends on the receiver you are using. My Garmin GTN650 does not have a GS antenna connection. However I believe the 430W and SL30 require a separate connection and it requires a splitter.
My Archer in the wing tip works great for GS. I do however get a interference with the HID lights on with the LOC. With HID lights off I get 100 miles. On only 50.
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09-15-2014, 03:25 PM
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Join Date: Mar 2012
Location: San Diego, CA
Posts: 133
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I have the SL30, and it has a built in splitter.
Like I said, it is not that it doesnt work, it is just the distance out from the airport that is not too far. I have the autopilot coupler in my RV, and it would be really nice to have that work reliably. I have done coupled approaches and once the glideslope catches on, it works great.
Did you come up with some shielding for the HID's?
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09-15-2014, 04:22 PM
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Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,797
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Two suggestions:
1. Temporarily run a piece of coax from the SL-30 up to the top of your windscreen; split it there into dipole (horizontal) for 330MHz (two arms, each should be about 9" long). Tape them temporarily to the windscreen, go fly. You won't get the localizer very well but the GS should work. If not, you have a problem with the radio. (The GS is a separate receiver from everything else).
2. I did not understand the part about the aluminum tape ground. The Archer design is predicated on having a vertical (electrically conducting) ground plane very close to the location of the ground side of the antenna. This is usually the outboard rib in our planes, and one usually rivets the ground side of the antenna to the nutplates which attach to the wing skin, which in turn is riveted to the rib which is only an inch or so away. IF you used aluminum tape to "extend" the ground further outboard in the wing tip, further away from the outboard rib, the antenna will not work properly, and the degradation will be worse at higher (GS) frequencies.
Some people think the antenna will work better if they get it further away from the rib and the wing, but RF antennas don't work that way.
Last edited by BobTurner : 09-15-2014 at 04:25 PM.
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09-15-2014, 04:57 PM
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Join Date: Mar 2012
Location: San Diego, CA
Posts: 133
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As far as the alu tape, it is the interface between the antenna and the wing, through the nutplates, just as you said. I need to take some pics. I will most probably go out there on Friday. The coax thing you mentioned sounds interesting!
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09-15-2014, 05:39 PM
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Join Date: Nov 2008
Location: Baton Rouge, LA
Posts: 671
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Nav issues
I have a VAL 2000 NAV, Archer Antenna, and Trutrak EFIS. My glide slope and localizer reception is OK but VOR reception is poor. I think it's EMI from the EFIS but I've never been able to fix it. I wasted a lot of time on the antenna. Even installed a second Archer in the other wingtip.
What tipped me off to the interference issue was my Sporty's handheld. I noticed that when I tuned the VOR on the handheld the reception would come and go depending on whether the EFIS was turned on. If you have access to a Handheld with glide slope you might use it as a test device to see if you're getting interference on the glide slope frequency.
These problems are the worst to me. Nobody seems to have an easy answer.
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09-15-2014, 06:53 PM
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Join Date: Sep 2011
Location: Edgewater, FL. KSFB
Posts: 1,118
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Hakan,
I had mounted the HID power supply on the outboard rib. Very close to the Archer. After finding the interference I moved the power supply inboard as far as I could. This helped but did not eliminate. I still get great reception so I left as is.
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09-15-2014, 07:00 PM
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Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,797
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To check for RF interference just try turning these things (strobe, HD lights, EFIS) off, while listening to a VOR; see if the signal to noise improves.
For the record, I have an HD landing light in the same tip as an Archer, and I hear increased noise but just during the first few seconds while the light warms up. I did mount the power supply behind the rib, inside the wing.
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09-15-2014, 07:46 PM
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Join Date: Jun 2011
Location: Indianapolis
Posts: 228
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Quote:
Originally Posted by hlangebro
I realize this have been brought up many times here on the forums, but I still havent found my smoking gun for my bad Glideslope reception. Everything is routed as per instructions. My ground is alu tape on the tip and on the wing, though nutplates. LOC works fine, but of course it is a different frequency.
First thing that comes to mind is if the alu tape provides enough ground? I could put in copper or add a separate ground strap....?
I also have strobes and HD led landing lights. Can there be an EMI issue?
All of you who had this problem, how did you solve it?
If the coax was bad, then I wouldnt have LOC and VOR reception either right?
It is not that I dont have glideslope reception, but I only get it very close to the airports, and I have tried a few airports and the result is the same. It is about 1-2 miles out at the most...
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If your receiver has a separate input (for G/S), make up a glide-slope antenna by stripping the shield off of last 16 inches of one end of the coax (leave the insulator on the center conductor) and connect the other end to the BNC connector. This makes a 1/2 wave antenna for the frequency of the G/S. I have one of these to my Garmin 430W slid down the left gear leg fairing of my RV-8 and it works great. Just costs a connector and a few feet of RG-400. YMMV.
__________________

Larry Anderson
Indianapolis
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At IU Health Retired :-)
Although Exempt,
Donated for 2020
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09-15-2014, 08:07 PM
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Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,797
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SL-30 has an internal splitter. So if localizer works okay, GS does not, and you have NOT installed any external splitters, the only thing left is the radio.
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