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  #1  
Old 06-15-2012, 03:18 PM
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Don Jones Don Jones is offline
 
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Default Home made glide slope antenna

Has anyone tried the stripped coax glideslope antenna in a gear leg fairing?
I have been considering where to put one. Thinking either the cowl or gearleg fairing. I don't want to use a diplexer to split my vor antenna to feed the glideslope to my 430. I suspect it might cause the signal to be directional, just thought someone here might have tried it. Paul??
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  #2  
Old 06-15-2012, 08:01 PM
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I seriously doubt it would work at all in the gear leg fairing. It would be way to close to the gear leg. The engine cowl may work, but it would need to be kept away from metal as much as possible. Neither place is really ideal. It may be worth a try, but a splitter is a lot easier. A splitter will not add directivity to an antenna. What are you doing for the nav antenna?
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  #3  
Old 06-15-2012, 08:28 PM
BobTurner BobTurner is offline
 
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As Bill said, you want to keep it away from metal. Also as horizontal as possible. That makes the gear leg a poor choice.

I use an Archer antenna in the wingtip for localizer, VOR, and GS with an SL30 which has an internal spliter. Works fine.
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Old 06-15-2012, 08:36 PM
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Radomir Radomir is offline
 
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Why not use a splitter.. they work just fine..
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  #5  
Old 06-15-2012, 11:26 PM
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Default Along roll bar

Quote:
Originally Posted by Radomir View Post
Why not use a splitter.. they work just fine..
I am not flying yet but plan to do like Paul Dye and run the stripped coax along the forward side of the windscreen, just in front of the roll bar. This has worked well for him so I will give it a try.

Cheers
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Old 06-16-2012, 12:01 AM
Flying Scotsman Flying Scotsman is offline
 
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Do you mean marker beacon, or glideslope?
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  #7  
Old 06-16-2012, 06:47 AM
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Mine has worked just great tucked along the roll-bar on the -8, and on the -3, we id exactly what you are suggesting (running it down the gear leg) and it has done just fine as well.

For those wondering why the spliter....the wingtip Nav antenna is extremely finicky in real-world installations, and the signal strength it delivers can end up marginal. Split it, and oftentimes, you don't' have enough left to drive the receivers. I started that way on the -8, and finally gave up - the simple home-made GS antenna fixed gave me better GS, and also better VOR range.

Paul
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  #8  
Old 06-16-2012, 06:52 AM
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Several people have had lousy glide slope reception with the Archer antenna in the wing tip like I have when using a splitter on the Garmin 430. Paul Dye went throuth it as well as Scott Card. Paul ran one up his roll bar and it made a huge difference.
Here is the thread http://www.vansairforce.com/communit...ad.php?t=40633

I don't have a roll bar, so I wondered if anyone had tried the gear leg fairing idea.
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  #9  
Old 06-16-2012, 05:00 PM
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I used a variation of the stripped coax GS antenna in the RV-8... made a 16" long strip of aluminum, about 3/8" wide and fiberglassed it to the floor of the right wingtip, sitcking as much straight outward as it could get, polarized horizontally. Attached the coax center conductor to the inboad end of the strip and grounded the coax to the outer wing rib. It seems to work just fine with the Garmin 430, cost was virtually noting. The coax was the only cost item.
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  #10  
Old 06-16-2012, 05:46 PM
BobTurner BobTurner is offline
 
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Neal's example shows how sensitive modern receivers are; almost anything will work, if it can see the transmitter without looking thru a lot of metal. 16" is "the wrong" length.

For an ideal antenna (that is, an infinite ground plane instead of the finite wing rib for a ground) the length of the antenna element should be about 9". (Remember the "bow tie" GS antennas, high up on the windscreen of 1970-era Cessnas?). 27" also works, and is what you want for the VOR frequencies.
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