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10-13-2014, 12:12 AM
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Join Date: Mar 2012
Location: San Diego, CA
Posts: 133
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The improvements were to do the routing exactly as per the instructions, and that is what it is now. The glideslope is intermittent, and works better flying FROM the glideslope, than flying TO it. Sometimes it works from 15 nm, then it stops, and then it starts working again at about 5nm. So basically, it is not that the G/S doesn't work, it just doesn't work well...
I have heard of quite a few people having the same issues, and either they replace the antenna with whiskers or a dedicated G/S antenna.
By stripping the coax, do you mean dividing the outer "lead" into 2? what about the inner part?
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10-13-2014, 12:55 AM
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Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,797
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To make the dipole, strip off the outer insulation, about 10".
Push the shield away from the end, so it expands, all the way down 10".
Work a hole in the shield by spreading the braid, bend the cable, and pull out the center conductor thru the hole in the shield. Grab the shield and pull it to the left, while pulling the inner conductor to the right, let the intact coax hang down. Trim the ends of the left and right pieces to 22.5 cm long each. Tape it to the windscreen.
BTW, mid 1970's Cessnas had a GS antenna on their windscreen. You might find one used somewhere cheap.
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10-13-2014, 01:30 AM
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Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,797
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I just noted that your wingtips are painted red. That's not metallic paint, is it?
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10-13-2014, 08:19 AM
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Join Date: Mar 2012
Location: San Diego, CA
Posts: 133
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Thanks, I will see what I can do. I saw some old Cessna G/S antennas somewhere...
The paint is not metallic, however, red paint always contains a certain amount of Gold.... It is raptor red by Sherwin-Williams
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10-13-2014, 08:19 AM
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Join Date: Jun 2012
Location: Frederick, MD
Posts: 821
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FWIW, I have the archer antenna in my wingtip and typically get good glideslope out in excess of 20NM, which is exceeds the normal published service volume for Glideslope (10NM). I have embedded wingtip LED nav/strobes. I use the SL30 for my glideslope receiver.
__________________
Dan Morris
Frederick, MD
PA28-140
Hph 304CZ
RV6 built and sold
N199EC RV6A flying
Learn the facts. "Democracy dies in darkness"
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10-13-2014, 12:26 PM
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Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,797
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Quote:
Originally Posted by RVDan
FWIW, I have the archer antenna in my wingtip and typically get good glideslope out in excess of 20NM, which is exceeds the normal published service volume for Glideslope (10NM). I have embedded wingtip LED nav/strobes. I use the SL30 for my glideslope receiver.
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Yes, me too except I have a HID light out there.
What is perplexing is the fact that the localizer works all the time (is this correct?) but the GS comes and goes. Theory and practice often diverge with RF stuff, but in principle if it works for the localizer it should also work for the GS. I think I asked before, but just to confirm, there is NO diplexer (GS/Localizer splitter) in the coax between antenna and SL30?
Also:
"Sometimes it works from 15 nm, then it stops, and then it starts working again at about 5nm."
This sure sounds like an intermittent connection somewhere, and the only place the GS and localizer signals are separated is inside the SL30.
If you cannot swap SL30's with a known good one, go ahead and fab a 18" (total length) dipole antenna, tape it to the windscreen and try it (this will in principle give poor performance for the localizer but should work for the GS). If the GS works, then the issue really is in the antenna. If it doesn't, you need to look at the SL30.
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10-13-2014, 12:51 PM
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Join Date: Mar 2012
Location: San Diego, CA
Posts: 133
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I have no diplexer. Also it seems very sensitive to turns, and as I mentioned earlier, it works better flying FROM the glideslope compared to flying TO, which, I think means blocking? or something....
I will get a splitter and a coax and try the G/S out, if it turns out the G/S works better but the LOC is worse, I guess then the only other alternative is to get the whiskers antennas and mount them on the lower aft fuselage...
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10-13-2014, 01:42 PM
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Join Date: Mar 2012
Location: San Diego, CA
Posts: 133
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Someone reccomended the CI 503 splitter for this, however it seems like this splitter is only good for the G/S freq (329.15-335), and not the VOR and LOC freq (108.1-117.95)....?
Is there another splitter I should consider?
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10-13-2014, 02:11 PM
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Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,797
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For the test, I would just skip any splitter. Unplug the existing coax which goes out to the wing tip, plug in the coax from the GS antenna, go fly.
The localizer and VOR performance will be very poor, but the GS should work just fine. If that is indeed the case, then assuming no fix is found for the Archer your next step is probably to install cat whiskers somewhere, and run a new coax to the SL30 - again, no splitters needed since the SL30 has an internal one to separate out the GS from the LOC/VOR.
You will only need the splitter if you decide to keep the Archer for VOR/LOC, and add a new GS only antenna. Then you would need to run the splitter/diplexer "backwards" of the usual application: Archer into the "VOR" output, GS antenna into the "GS" output, and the "antenna input" to the SL30.
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Your theory of shadowing would make sense if it happened to both the GS and the LOC signals -when you're 15 miles out their antennas "look" like they are practically on top of each other. Try this: check out the airport, and see what side of the runway the GS antenna is located. If it is on the left (as seen approaching the airport) then while on the ILS slip the nose to the left, see if that improves GS reception. If it does then maybe the issue is some sort of shadowing which is right on the edge of working/not working.
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Just to confirm: your Archer is installed with the end where the coax attaches near the front of the wing tip, and the longer unsupported end facing aft? and on the bottom of the wingtip, laying flat (horizontal not vertical)?
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10-13-2014, 04:12 PM
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Join Date: Mar 2012
Location: San Diego, CA
Posts: 133
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The installation of the archer is on the right tip. It is installed on the top portion of the tip, with the harness up front and the long portion pointing back.
Last time I flew I tried to sideslip and roll to get the G/S but nothing seemed to help.
When I was flying FROM the airport and noticed the G/S working, I didnt pay attention to the LOC so I couldnt say for sure if it was working or not...
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