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  #11  
Old 12-17-2009, 04:44 PM
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RV8RIVETER RV8RIVETER is offline
 
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Pretty much the same place as Mr. Schreck. Mine is about 8 inches behind the last bulkhead below the pass seat, left bay. Was going to put insp plate in baggage floor, but decided to try and test without and have no problems removing ant dropping it enough to unscrew connector, so didn't install one.
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  #12  
Old 12-17-2009, 05:54 PM
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Default Which Bay

Those of you who put the transponder antenna behind the back seat under the baggage floor, is it in the same bay as the rudder cable? I was thinking the middle bay, the one with the push rod connected to the bell crank. The travel of that rod will not interfere with the antenna cable if it is off to the left or right. I could put it int he left bay under the step support, looks like it will take just over 8 feet of cable to put it back there. I have conduit so changing the cable to something that will allow a longer run will be easy if there ends up being a problem with ATC picking up the transponder. Thanks for the inputs, I guess I can always put it someplace else and patch the hole if it does not work out.

I am going to go someplace just aft of the F807 bulkhead, this meets all of the parameters for antenna placement except for the length of RG400 cable, seems like no one is having issues with it this far back.

Cheers
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  #13  
Old 12-18-2009, 05:19 AM
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Quote:
Originally Posted by RVG8tor View Post
Those of you who put the transponder antenna behind the back seat under the baggage floor, is it in the same bay as the rudder cable?

Cheers
Yes. It is at the very front of that bay. No way can it interfere with the rudder cable.
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  #14  
Old 09-16-2011, 09:06 AM
tonyjohnson tonyjohnson is offline
 
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Default bump for recent input

I am bumping this thread to see if there is any recent information before I start cutting holes in my fuselage.

I am considering the positions in the pic of the OP. Two bent whips, one on each side of the fuselage, just forward of the spar. Transponder antenna further aft, perhaps in the position recommended by Paul Dye. Archer nav antenna in the wingtip. That leaves the marker beacon antenna that I have not yet thought through.

I am building an 8A.

Do any of you who are flying have any reason not to go with the above positions?

Thanks
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  #15  
Old 09-16-2011, 10:53 AM
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We also mounted the transponder antenna (shark fin) under the baggage compartment floor. I used RG-400 coax and a low-profile 90-degree adapter at the antenna end to help keep the coax and connector well clear of any moving parts back there.

The com antenna is a bent whip, also mounted on the belly, just behind the trailing edge of the wings and about 18-20 inches forward of the transponder shark fin.

You can see them both in this pic, taken when I was departing from Osh. The thought of mounting both these antennas so far aft, was to help keep their propagation patterns from getting "shrouded" by the wings so much. They seem to work great and have a good omnidirectional propagation to them. On the way home from Oshkosh, I was able to keep talking to my buddies as they approached the DFW metroplex while I was just crossing the Kansas/OK border just north of Enid, OK.
http://www.airport-data.com/aircraft/photo/658556L.html

We've also got a Bob Archer VOR antenna in the left wingtip, and a homemade glideslope antenna made from a thin aluminum strip in the right wingtip.

We don't need no steekin' marker beacon
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Last edited by Neal@F14 : 09-16-2011 at 11:09 AM.
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  #16  
Old 09-17-2011, 09:12 PM
SHIPCHIEF SHIPCHIEF is offline
 
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Neal;
Could you give some detail on the glideslope ant?
I've go the Bob Archer Nav Ant going in the left wing, and a wireway to the right wing, so I think you have a good set up that I would like to copy.
I have an ADF Ant in the aft fuse, behind the elevator bellcrank, so I'm thinking the Com Ant can match yours, but the Transponder will go under the rear footwell.
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  #17  
Old 09-18-2011, 06:45 AM
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In my RV8A I have the GTX-327 txpndr antenna in the same place as Paul Dye and I have yet to have anyone complain. Access is also easy as it is just under the ring root fairing. This seemed the simplest solution given the limitations.

My single comm is just left outboard of the center section inside of the left rear foot well. Again, no complaints and I pick up signals at long range as well.
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  #18  
Old 09-18-2011, 07:18 AM
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Having done a fair amount of transponder testing I have found antenna location is more important than cable length. I have tested the 327 with probably a 15 ft RG400 run and power was still over 200W. If you shadow the antenna with gear legs/exhaust/other antennas/etc. that always causes problems for me when groung testing and sometimes makes it hard to get a transponder to pass the test (both MTL and power).
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  #19  
Old 09-18-2011, 01:17 PM
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Quote:
Originally Posted by SHIPCHIEF View Post
Neal;
Could you give some detail on the glideslope ant?
I ripped off the idea from Paul Dye, who used a piece of coax with 16" of shield stripped away as a glideslope antenna.

Since glideslope is a horizontal polarized transmission, and 16" is the length that Paul's homemade antenna was working well with (half-wavelength?), I simply glued a 16" strip of 0.020 aluminum (about 3/8 inch wide) to the bottom inside of the right wingtip, extending outward as straight as I could, but angled rearward somewhat due to the available size of the "floor" of the wingtip. At the inboard end of the aluminum strip, I drilled a hole and connected the center lead of the coax with a crimped-on ring terminal and a 4-40 screw and nut, and grounded the shield of the coax to the outboard end of the wing itself. In Paul's post with his homemade coax GS antenna he said he was able to pick up the glideslope as far out as 20 miles.... we're only getting about 10 miles, but Paul and others who've made homemade GS antennas like this are not grounding the coax shield at the antenna end, only at the radio end. Someday I plan on disconnecting the shield ground out on the wingtip end and see if that improves reception.
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Last edited by Neal@F14 : 09-18-2011 at 01:19 PM.
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  #20  
Old 09-19-2011, 05:20 PM
tonyjohnson tonyjohnson is offline
 
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Default archer nav antenna functions

Just when I thought that I had my antenna plan pretty much under control, new information arises.

One issue is the archer nav antenna that I will have in one wingtip. I thought that antenna recieved VOR, Localizer and Glideslope information. Then I read Neals post regarding the Paul Dye improvised glideslope antenna. I know that Paul was using an archer nav antenna.

So, does the archer nav antenna provide glideslope information as well as VOR and localizer?

If I use a separate glideslope antenna, where do I connect it to my SL30??
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