Antenna Suggestions (VHF) Kitfox model III

[LSaupe 123]

Getting ready to order a VHF anenna for my Model III. Plan to mount in the top position aft of the turtle deck.

 

Any suggestions or things to avoid here?

 

Larry

[EDMO 1078]

Hoping you have installed a mounting plate !    sorry, I'm not anenna educated...

I still have not figured out how my Sporty's 400 radio is supposed to pick up VOR radials without a VOR antenna.

EDMO

Edited 30 May 2015 by Ed In Missouri

[C150L 6]

Here's one to consider. Mounts inside the fuselage.

 

http://personalpages.tds.net/~pajohns/antenna.html

 

(Yup, it's me.)

[C150L 6]

OOPs, I'm not Paul.

 

Dale

[EDMO 1078]

One of the electronic gurus advocated putting a copper or aluminum foil of "proper diameter" under the fabric, but this could probably be done with 4 squares of that material making a cross, as long as each is grounded to the mount and antennae.

EDMO

[LSaupe 123]

Hoping you have installed a mounting plate !    sorry, I'm not anenna educated...

I still have not figured out how my Sporty's 400 radio is supposed to pick up VOR radials without a VOR antenna.

EDMO

 

Would this be different than the factor plate (or what I think is an antenna plate)?  I have 2, OEM install, one on top, just aft of the turtle deck and one on the bottom just aft of the cockpit on the pilots side. 

[MarkD 53]

I don't know if you have ordered an antenna yet but, I installed two ELT antennas one on each side of the turtle deck. One for the ELT and one as a Comm antenna. The ELT antennas are relatively inexpensive and for the low speeds our airplanes operate at they are structurally just fine. The ELT antenna is cut to be resonant at 121.5Mhz, which is the middle of the VHF aircraft band. They have broad enough resonance to be matched for the entire band well enough for the typical low power of onboard aircraft Comm radios. If you are installing a radio that has VOR capabilities then it usually has a separate antenna lead for a horizontally polarized VOR antenna. We do not have to have TSO'd Comm antennas required for Certified aircraft that may operate under adverse conditions and have to hold up to situations like Icing.

Just my 2 cents...

MarkD

[TJay 1041]

I like this inside antenna made by Paul, Does anybody have any experience with it and how well it works. I would sure think i could fit it some where inside the kitfox.

[ChrisBolkan 130]

Most likely the inside mount antenna is a ground plane-less dipole with a balun transformer. Super great antennas but will only work in a composite or wood airplane. The builder of my Magnum installed one in the tail and it did not work very well because the antenna coupled into the nearby metal  parts of the empanage nd produced a lot of "shadows" in the polar response.

[KFfan 151]

When I investigated the inside mount antenna, I discovered the same restriction as Chris mentioned. I would not put one in a kitfox.

$.02

[C150L 6]

Quick FYI,

 

It is a "no ground plane required" antenna.

 

There is NO balun used in this design. A balun (BALances the UNbalanced) can rob up to 50% of the energy the radio puts out. All of the energy the radio puts out, goes directly into the antenna with this design and out to the radiating elements.

 

This antenna can be used in composites, but not with in carbon fiber. CF is about as disruptive as steel to the RF signals.

 

I could not picture this antenna working in a metal framed tail. Just no way to keep it away from the metal framework. It could work great in a fiberglass/composite tail.

 

When installed in the fuselage, this antenna is suspended off it's three points, in a V (actually a Y) formation and is positioned away from the metal framework as much as possible, with one arm as near vertical as possible.

 

I know of many Cubs, Champs, Stinsons, T-crafts, a Hats and custom configuration in a Hiller.

 

One guy with a Champ complained to Paul, saying he just wants to talk at our local airport, not the entire state. Another Champ guy complained his did not work. Guess he was right. It was later mentioned (by someone else) that he had zip tied it directly to the fuse tubing. That certainly will not work. I had one in my Koala (wooden FP-202) and did a radio check to another plane in the pattern an airport 100nm away using my antique STS handheld. He said he heard me just fine but a little static was coming through. I asked if it might have been the 277 I was flying behind in an ultralight. He says that would explain it.

 

I don't know what else I can say about Paul Johns antenna, other than Paul no longer builds these. I do. One at a time. (Well, maybe 6 at a time), then test and tweak each one with a rather expensive antenna analyzer for best % match and to resonate at about 125mhz, which is just below the center freq of our radios bandwidth. We mostly use 122.8 anyway, that's why I brought them down a couple mhz. These are a very broadband antenna to begin with and had no issues/complaints when built up around 127mhz.

 

No expert, no salesman. Just pointing out an alternative for OP.

 

Dale

 

 

 

I'd certainly answer any question(s) I can.  

Edited 24 Jun 2015 by C150L

[dholly 718]

Folks, I have one of these antennas and I can vouch for its performance. In fact, knowing pretty much nothing about the technical end of antennas, I was -very- surprised at how well it worked. Hooked up to an old King KX99 handheld in my home shop, I promptly pulled in a bunch of previously unheard chatter at airports many miles beyond the large hills immediately to my south. Hung up in my metal hanger, radio tests using my Yaesu handheld generated extremely positive comments from the recipients regarding clarity and signal strength. I look forward to trying in one of my tube and fabric planes someday, just need to figure out the most optimum mounting location where it won't be in the way. If there is a downside to this antenna, it is rather large compared to alternatives which can be a factor in our smallish planes.

[RobS 52]

What are the dimensions?

[dholly 718]

Rob - wish I saw your post before I went to the hanger today. If I had to guess, I'd say the long legs are at least 20", overall at least as wide when open. I'll try to remember to measure next time I go out, maybe Dale will see this and chime in with the facts first.

[RobS 52]

Doug,

No problem and no rush as I'm a long way from needing to know. I was thinking this might be a good choice and your performance comments convinced me, but your final comment on its rather large size made me wonder where it could fit. The baggage locker could make it difficult . . .

[C150L 6]

One ringie dingie, two ringie dingies,,,,,    (Chiming in.)

 

I will get some measurements when I get home and after family get together/cook out.  A friend of minne has installed many of these, but not sure in Avids or Kitfoxes. I know he just did some work on an Avid around the time I sold him one. I'll see what he knows and if he has any pictures. Aircraft rebuilds is his business and he takes a lot of pictures.

 

If nothing else, I'll wheel out our Avid project and put one in for some pictures. (Sometime when not out flying the oldest 150 you will ever see.) I will have to keep in mind, the mixer and push rods in most as ours (if ever finished) has the mixer under the seat and will be using cables.

 

I did install one through a narrow crawl hole space in the back of a flying KR2S a few years back. Not a big plane and was room to spare when done, although it looked like it was going to be tight. Guy in the FBO/terminal building did not believe that we were across the field in the steel quanset hut hanger, using a handheld in his KR when I did the radio check. When installed properly, the performance should be there.

 

Thanks Doug for the performance info.

 

Dale

Edited 27 Jun 2015 by C150L

[RobS 52]

Thanks Dale!

[C150L 6]

Each arm measures 23", short limb 5". You can subtract 1/2" off each if measuring to the bolted, folding point where all pieces come together. Opens up to 39" overall width, which can vary some when installed. My good friend  Paul designed this antenna specifically to be installed in tube and fabric aircraft. Certain composites and wood aircraft also fit the design as well.

 

I just held one in place in our slightly buried Avid project, between the next 2 stations behind the mixer area and appears to stand up nicely there. Could be a challenge if fuse is already covered, but I'm inclined to think anything is possible.

 

Still want to pull our project and install one for pictures, but can't happen this one day week end. (What's left of it.)

[EDMO 1078]

OMG - How did I ever survive flying so many years without a radio or ELT or GPS or computers or phone !!!

I also drove a wagon pulled by a team of mules, and learned to drive on a stick-shift tractor and an old truck....

EDMO

Edited 28 Jun 2015 by Ed In Missouri

[C150L 6]

AAHH, Ed. I'll have to get a close up look at the driver on my encased 20 Mule Team wagon train model and see if it looks like you.

[RobS 52]

So the 39" dimension is the distance between the tips of the longest arms - correct?

[EDMO 1078]

C150L,

     Never saw a 20-mule-team - Just two old mules that had been farting and swatting flies with their tails while I gathered a wagon load of tall corn by hand on a hot July day!  SUCH fun!  No radio or GPS either! 

EDMO 

Edited 28 Jun 2015 by Ed In Missouri

[TJay 1041]

so can that sucker be mounted any direction in the plane or does it have to be vertical?

[C150L 6]

So the 39" dimension is the distance between the tips of the longest arms - correct?

That is correct. The tips of the wood arms could be trimmed a little if needed and bring that down a little as well. The wood arms are basically window screen molding, if one wanted to make a mock up piece to check out in their plane/project. The antenna itself is mounted to that wooden structure.

[C150L 6]

so can that sucker be mounted any direction in the plane or does it have to be vertical?

One arm should be mounted as near vertical as possible for polarization and getting best omni-directional function. I have tried one stretched out straight and hanging horizontally and it worked ok, but I would not do such in any installation. At this 39" V configuration, the antenna analyser gives the best performance across the entire VHF band width, best % of match and resonates at about 125mhz.

 

(Starting to feel like a salesman here,,,,  but like answering questions best I can.)

Dale

Edited 29 Jun 2015 by C150L