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d-m-hague(at)comcast.net
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 Posted: Sat Oct 13, 2007 5:18 pm Post subject: Antenna location |
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I know much of this has been discussed before, but I have a couple of different considerations, and I need to figure out where to mount the com antenna on my Ultrastar. The included rubber duck antenna works fine until I connect the helmet, then I get a horrible squeal (RF feedback), so I need to remote the antenna. Looking for opinions on the alternatives: - On the tailboom, near the tail. I'd have to drill a hole in the tailboom for the cable to pass through, but I figure that'd be OK if it's smaller than, and behind, the existing hole for the folded wing support bracket? Could put it either on top or on the bottom, and the boom tube would probably make an adequate ground plane. That'd put it just forward of the rudder or subfin.
- On the tailboom, farther forward (just behind where the center gap seal ends, or perhaps farther forward if I poke a hole in the gap seal). The advantage is a shorter cable, and I could run the cable outside the tube and clamp it around the tube, so no drilling holes, but more chance if ignition noise with the engine just below it?
- Under the floorboard (no pod on my plane), pointing down. Short cable, good ground plane, but anything longer than the original rubber duck antenna would probably be too long. Might be too close, though, and still get the RF feedback.
- Out on the wing somewhere, perhaps clamped to the upper end of the wing strut pointing down. Here I'd have to run the cable down the strut, and have a disconnect at the bottom of the strut (I fold the wings every flight).
- Or someplace else?
I'll probably use the rubber duck antenna at the end of the coax anyway... according to Icom it doesn't need a ground plane, and it has better bandwidth than a steel whip at the cost of some loss, which should give better VOR performance (I have the A24 with the VOR functions).
Sigh... trailered the plane to the airport today... spent all day waiting for the winds to die down as forecast... and trailered it back home again.
-Dana
--
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But do you trust the _government_ with semi-automatic assault rifles? [quote][b]
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jbhart(at)onlyinternet.ne
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| Posted: Sat Oct 13, 2007 5:55 pm Post subject: Antenna location |
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X-Mailer: QUALCOMM Windows Eudora Version 5.1
Date: Sat, 13 Oct 2007 21:12:40 -0400
| Quote: | >>>>>>>>>>>
I know much of this has been discussed before, but I have a couple of different considerations, and I need to figure out where to mount the com antenna on my Ultrastar. The included rubber duck antenna works fine until I connect the helmet, then I get a horrible squeal (RF feedback), so I need to remote the antenna.
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| Quote: | >>>>>>>>>>>>>>>>>>>>>>
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Dana,
I have had similar RF feedback problems, and I solved them with split
ferrite collars. See the top of:
http://www.thirdshift.com/jack/firefly/firefly110.html
These split ferrite collars can be purchased online from All Electronics
at:
http://www.allelectronics.com/cgi-bin/category/235/Ferrites.html
Just pick the size that will let you loop the helmet cable through the
inside twice. Place it as close to the radio as possible. If this does
not work then try a remote antenna.
Jack B. Hart FF004
Winchester, IN
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d-m-hague(at)comcast.net
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| Posted: Sat Oct 13, 2007 6:09 pm Post subject: Antenna location |
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At 10:00 PM 10/13/2007, Jack B. Hart wrote:
| Quote: |
I have had similar RF feedback problems, and I solved them with split
ferrite collars. See the top of:
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Thanks Jack, I already tried that (and lots of other things as
well). Nothing worked; apparently the A6/A24 radios are particularly
susceptible to RF feedback.
-Dana
--
--
But do you trust the _government_ with semi-automatic assault rifles?
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Thom Riddle
Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)
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| Posted: Sun Oct 14, 2007 3:40 am Post subject: Re: Antenna location |
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Dana,
My Firestar came with an antenna mounted roughly mid-point on the boom tube. Whoever added it did not drill into the tube but ran the cable on the outside underneath so it would not be visible. The cable is held in place with self-adhesive cable tie anchors.
Unfortunately, I have no idea how it works because I never got around to using my hand held radio with it before my unfortunate pothole landing incident. Once it is flying again, I'll eventually get around to trying out the radio.
do not archive
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Thom Riddle
Buffalo, NY (9G0)
Don't worry about old age... it doesn't last very long.
- Anonymous |
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planecrazzzy
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| Posted: Sun Oct 14, 2007 4:02 am Post subject: Re: Antenna location |
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I put my antenna on my Wing-Gap seal.... ( it's aluminum )
I also have my ELT antenna on it....
My transponder antenna is sticking out the bottom where the passenger sits.....but that one needed a grounding plane , I slipped it between the tubing and fabric....
I got rid of my rubber ducky antenna ,Bought the straight one from ACS
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"I" sure wouldn't go putting holes in my tail boom ( but that's me )
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I was told the antenna should also be "straight" up & down....
( I was going to put a Bent one on the belly )
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Gotta Fly...
Mike & "Jaz" - Building a Buttercup
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http://groups.yahoo.com/group/Buttercup-STOL/
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| Description: |
| Old rubber ducky antenna , suction cupped on the left side, hanging down,under plane... |
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lcottrell
Joined: 29 May 2006
Posts: 1494
Location: Jordan Valley, Or
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| Posted: Sun Oct 14, 2007 7:30 am Post subject: Re: Antenna location |
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For what it is worth, I had to mount my antenna on the belly of my Firestar. I tried it on the top of the windshield and the noise was so bad that it was unusable. I had put a alum plate right on the bottom of the cage just behind the pilots seat. it is 23.5 inches long and bent so that it clears the ground. I had no problems with a 447 on the plane. When I changed to a 503 the noise was really bad. I ended up with ferrite chokes to cut down on the noise. I believe all that is in the archives.
Larry,Oregon
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John Hauck
Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)
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Thom Riddle
Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)
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| Posted: Sun Oct 14, 2007 3:16 pm Post subject: Re: Antenna location |
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John H,
I appreciate your humor about my pothole landing.
From my own estimate, my eye level was probably about 7-8 feet above the ground when I stalled. According to Bob Bean who witnessed the whole thing, he said the wheels were perhaps 2-3 feet above the ground which jibes well with my eye-level assessment. No argument about having stalled before hitting the pothole. I firmly believe that if I had not hit the pothole after stalling from 2-3 feet the damage would have been a lot less. The pot hole made a bad landing far worse than it otherwise would have been. If I had already landing properly and then hit the pothole the results would likely have been far less damaging too. The combination of my admittedly bad landing (stalling too high) and the bad luck of hitting the pothole upon hard touch down was more than the axle weldment could withstand.
On a positive note, not having built a Kolb, I'm learning a lot more about the Firestar than I would have without this incident.
do not archive
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Thom Riddle
Buffalo, NY (9G0)
Don't worry about old age... it doesn't last very long.
- Anonymous |
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John Hauck
Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)
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| Posted: Sun Oct 14, 2007 4:43 pm Post subject: Antenna location |
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The pot hole made a bad landing far worse
| --------
| Thom in Buffalo
Thom:
Been there and done that, minus the stall.
It was a large rut on a dirt trail across the gravel strip that took
off my left wheel and axle at Muncho Lake, BC, 1 July 2000. That is
what initiated it. The gear leg/axle socket had many thousand
landings on it, was waiting on a trigger. If I had not gotten it at
Muncho Lake, it would have failed some place else on down the line.
It failed at a place that had food, lodging, and a telephone.
Rebuilding a Kolb is a good way to learn about how they are built. It
is also a good time to make changes to them that you did not know
about until you have flown them for a while. We did a major overhaul
update on my FS after the accident in 1988. Next year we flew it back
up through all the New England states, Sault Saint Marie, Canada, and
south into OSH. The updates and rebuild paid off. Made all that work
worthwhile, plus the little airplane was set up the way I wanted it.
Was a neat little bird that eventually flew in all the States east of
the Mississippi, some west of the Big Muddy, and Canada. Not bad with
a little 447 point ignition Rotax and a wooden prop.
john h
hauck's holler remote, Lincoln, Nebraska
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John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama |
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Was my understanding you were finished flying long before you hit