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Bob Turner
Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA
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 Posted: Thu Dec 06, 2012 12:12 pm Post subject: Archer type wingtip antennas |
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The post of "Glide slope antenna" has drifted to this topic, so I am starting a new thread:
I have Archer type antennas for both VOR/Loc/GS and #2 com, and in general am satisfied. I think this is due to:
1. Luck
2. I have low standards, or
3. I did not follow the directions exactly.
In case it is #3, I thought I'd post what I did. I think the instructions were written for installation in a -7, where the smaller tip required that the antenna be close to the lights. The -10's tip is big enough that this can be avoided. I mounted my antennas at least 8" aft of the lights, aluminum foil heat shield, etc. I did NOT run the wiring for the lights along the antenna. Instead, I kept it inside the metal wing, ran it as far forward as I could, then thru the end wing rib directly to the lights. The VOR antenna is on the bottom of the wing tip, with the ground leg riveted under the wingtip attach platenuts. For the com antenna, I mounted the antenna so the leg where the feed line attaches - where most of the current flows - was at the thickest part of the wing. I riveted the ground side to the top of the tip, then bent the leg with the feed line down as much as I could, until the long arm of the antenna was against the bottom of the wing tip (where I hold it in place with a little fiberglass). This gives the maximum amount possible of vertical polarization. To be clear, the wingtip antenna is NOT as good as the vertical whip under the plane. But it works for me as #2. At 20 miles out tower described it as "5x4" (readability-strength) while the external whip was "5x5".
As to the question of building your own: I won't post the exact Archer dimensions since I think it is copyrighted. But you can look up the general idea at the library, find a copy of the ARRL (Amateur Radio Relay League) book and look under "gamma match". Generally speaking you will need some equipment, like an SWR meter, to tune the antenna. If you decide to reverse engineer an Archer, note that the size, especially the thickness, of the built-in parallel plate capacitor, is important, as is getting the same dielectric constant for the material he uses (looks like Bakelite) between the plates. For the com, shorten the antenna by about 10% compared to the VOR antenna to account for the 10% higher frequencies.
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Bob Turner
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Mauledriver(at)nc.rr.com
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| Posted: Thu Dec 06, 2012 1:26 pm Post subject: Archer type wingtip antennas |
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Since I made the previous comment about the Archer not being suitable
for Com2, I'll comment further...
Bob, I didn't move the location rearward like you did but I thought
about it a lot. Sounds like a good move. I did try to maximize the
vertical polarization like you did except I did it upside down.
And the antenna did work and work reasonably well. No problem at all on
the second radio. Not much of a problem as a primary comm for VFR. In
my case, my com1 failed at the furthest point from home I've ever flown
in my life (how did it know that?). Flying 2,000 miles IFR with a less
than a top performing comm tends to cause a disturbance in the force so
I decided it wasn't for me.
Just elaboration on my experience
Bill "do not archive" Watson
On 12/6/2012 3:12 PM, Bob Turner wrote:
| Quote: |
The post of "Glide slope antenna" has drifted to this topic, so I am starting a new thread:
I have Archer type antennas for both VOR/Loc/GS and #2 com, and in general am satisfied. I think this is due to:
1. Luck
2. I have low standards, or
3. I did not follow the directions exactly.
In case it is #3, I thought I'd post what I did. I think the instructions were written for installation in a -7, where the smaller tip required that the antenna be close to the lights. The -10's tip is big enough that this can be avoided. I mounted my antennas at least 8" aft of the lights, aluminum foil heat shield, etc. I did NOT run the wiring for the lights along the antenna. Instead, I kept it inside the metal wing, ran it as far forward as I could, then thru the end wing rib directly to the lights. The VOR antenna is on the bottom of the wing tip, with the ground leg riveted under the wingtip attach platenuts. For the com antenna, I mounted the antenna so the leg where the feed line attaches - where most of the current flows - was at the thickest part of the wing. I riveted the ground side to the top of the tip, then bent the leg with the feed line down as much as I could, until the long arm of the antenna was against the bottom of the wing tip (where I hold it in plac!
e with a little fiberglass). This gives the maximum amount possible of vertical polarization. To be clear, the wingtip antenna is NOT as good as the vertical whip under the plane. But it works for me as #2. At 20 miles out tower described it as "5x4" (readability-strength) while the external whip was "5x5".
As to the question of building your own: I won't post the exact Archer dimensions since I think it is copyrighted. But you can look up the general idea at the library, find a copy of the ARRL (Amateur Radio Relay League) book and look under "gamma match". Generally speaking you will need some equipment, like an SWR meter, to tune the antenna. If you decide to reverse engineer an Archer, note that the size, especially the thickness, of the built-in parallel plate capacitor, is important, as is getting the same dielectric constant for the material he uses (looks like Bakelite) between the plates. For the com, shorten the antenna by about 10% compared to the VOR antenna to account for the 10% higher frequencies.
--------
Bob Turner
RV-10 QB
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Bob Turner
Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA
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| Posted: Thu Dec 06, 2012 2:29 pm Post subject: Re: Archer type wingtip antennas |
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Bill, I understand. I think my #2 is good enough that if I had to use it it would not be an emergency, and I would complete the leg or flight. I would expect to hear ATC okay, while my transmissions might be weak. As to continuing on, I personally won't launch IFR unless everything in the panel is working, so that is not an issue for me.
I like having one less thing under the plane which can poke my eye out.
Also, I have had times on the ground when the tower could not hear me with the belly whip. Wingtip antenna always worked when that happened.
Bob
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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Bob Turner
RV-10 QB |
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mauledriver(at)nc.rr.com
Guest
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| Posted: Thu Dec 06, 2012 9:11 pm Post subject: Archer type wingtip antennas |
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Totally agree.
Bill
Do not archive
Sent from my iPad
On Dec 6, 2012, at 5:29 PM, "Bob Turner" <bobturner(at)alum.rpi.edu> wrote:
| Quote: |
Bill, I understand. I think my #2 is good enough that if I had to use it it would not be an emergency, and I would complete the leg or flight. I would expect to hear ATC okay, while my transmissions might be weak. As to continuing on, I personally won't launch IFR unless everything in the panel is working, so that is not an issue for me.
I like having one less thing under the plane which can poke my eye out.
Also, I have had times on the ground when the tower could not hear me with the belly whip. Wingtip antenna always worked when that happened.
Bob
--------
Bob Turner
RV-10 QB
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=389979#389979
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