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dedicated glideslope antenna

hlangebro

hlangebro

Well Known Member
I have the Archer VOR antenna in the right wingtip. It works ok for VOR and LOC, but very intermittent on glideslope, no matter how many changes and improvements I have made. Part of the issue is probably the HID light and strobes etc.
Anyway, I was thinking about installing a dedicated glideslope antenna. I found this internal antenna and would like to know if anyone has used it?

http://www.chiefaircraft.com/ci-193.html

Here are some pics of where I was thinking about installing it; upper canopy area or lower canopy area:

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I have the SL-30, and according to the manual you can use a splitter, not diplexer, for the split input signal.

Any input/ideas?
 
Do a search...

Several have simply stripped a piece on coax (I believe) and run it under a gear leg fairing. If my feeble memory serves me correctly, I believe Paul Dye (Ironflight) wrote it up one time.
Save yourself 200 bucks.
 
jarvis said:
Several have simply stripped a piece on coax (I believe) and run it under a gear leg fairing. If my feeble memory serves me correctly, I believe Paul Dye (Ironflight) wrote it up one time.
Save yourself 200 bucks.
Click to expand...

Yup - we have an antenna like this on both our RV-8 and the RV-3 - both work great!
 
We have a piece of stripped coax in a wingtip of our -9 that has always flown the GS perfectly :). I'm exceptionally happy with it, and we use it often.
 
antenna

Ok..... Can any of you provide me with a link so I can see exactly what you have done? I don't think the location in the wingtip will work, since I have issues with the lighting as it is....but nevertheless, I would like to se how you did yours :)
 
I took Paul's idea but placed the coax antennae in the front of my right gear leg faring. Always has worked well
 
hlangebro said:
Ok..... Can any of you provide me with a link so I can see exactly what you have done? I don't think the location in the wingtip will work, since I have issues with the lighting as it is....but nevertheless, I would like to se how you did yours :)
Click to expand...

Just search "Glide Slope Antenna" here. We hashed this out back in 2009.
 
I found some, however, if I wanted to go with the antenna I listed in the first post, where would be the best location??
 
hlangebro said:
I have the Archer VOR antenna in the right wingtip. It works ok for VOR and LOC, but very intermittent on glideslope, no matter how many changes and improvements I have made. Part of the issue is probably the HID light and strobes etc.
?
Click to expand...

1. Did you try turning the HID and strobes off, and/or re-routing their wires?
2. Have you checked out the SL30's glide slope? I have never heard of anyone else having a similar issue with an Archer.
3. I have seen a few other installations with "changes and improvements". They usually make things worse.
 
Just strip a coax to make a half wave dipole (45 cm total length, 22.5 cm each leg), tape it horizontally near the top of your windscreen, plug it into the SL30 and see if the GS works. If it does not, then the issue is inside the radio.
 
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?
 
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.
 
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
 
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.
 
RVDan said:
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.
Click to expand...

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.
 
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...
 
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?
 
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.
====
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.
==
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)?
 
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...
 
I made a coax antenna and tried it out today. It is the same as before, however as expected, the Loc wasn't as good. The weird thing is that it works out at 15nm and then the close I get the worse the reception. Also if I stay directly on the localizer, the GS works ok, but If I turn just a little bit the GS becomes intermittent... very strange. Also it still seems to work better flying FROM the airport...
Not sure what to do next....

Here are some pics of the temporary antenna


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Surprised you couldn't get the archer to work? Just for a data point for you; I have the Archer Nav in my right wingtip to an SL 30 / G3X and can pick up localizer and GS from KCRQ out over Lake Henshaw. Maybe check that install one last time?
 
Since the dirt-simple antenna didn't fix anything, time to look at the box. You need to find someone with a known good SL-30 and do a swap, test yours in his and vice versa.

I'll volunteer if you want to fly up to LVK (Bay area).
 
I am anxiously awaiting a resolution on the issue. I have a D180 displaying a GNS430W (Nav1) and/or an SL30 (Nav2). I know the glide slope used to work, but now doesn't with either radio. SO what changed???

I have the archer wingtip nav antenna to a triplexer that splits out the Nav1 and GS signal for the GNS430W, and the Nav2 for the SL30.
Localizer and VORs display just fine. the GS is flagged. I've checked installation and connections.

I've asked Dynon if some configuration or update issue might be to blame.

Just thinkin....

Don
 
These radios do have analog outputs for driving conventional CDIs. If you suspect the Dynon you can bring the analog GS flag line out to the passenger seat, hook it to a voltmeter and go fly and check it out.
 
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