What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

VOR antenna mounting help request.

Mike S

Mike S

Senior Curmudgeon
I am in the process of installing a SL 30 in my plane, and one of the tasks it going to be installing the antenna for the VOR.

I have a Rami AV 12, and am planning on installing it under the rear fuse.

product-view.php


Do any of you out there have photos or information about the best method of mounting/installing this antenna in this location?

As near as I can tell, it would seem best to mount it exterior of the plane, with the coax leads facing down, then to fabricate a fiberglass fairing to cover it up.

This will require only three holes in the fuse, two for mounting bolts, and one for the coax. Otherwise, if I try to mount it inside the fuse, it would seem that I will need more, and larger holes in the fuse. My concern is that this is a high stress area, and I am not planning on a "Swiss Cheese" approach to mounting.

Another option is to make a saddle type of mount to fit the antenna to, and rivet it under the fuse, mounting the antenna to the saddle, requires one coax hole, and four rivet holes.

I am not considering trying to mount the antenna on top of the vert stab, as the access in just not going to be possible without a lot of extra work.

Thanks in advance.
 
Last edited:
Mike, one thing is you do not need a ground plane so that may open options for you in mounting. Did you build your balun?
 
I have not yet done the balun, but thanks to you and others, it is going to be a non issue.

Big concern at this time is how to mount the antenna on a flying airframe with the least hassle.
 
Nav Aentenna

Mike

Give me a call and i have several ideas. I have looked at this extensively and might have some ideas.

Cell 707-479-5895
 
Ron Lee said:
Why don't you use the antenna system (Archer?) that will fit inside a wingtip?
Click to expand...

Too lazy, and too cheap.

I already have the Rami antenna, dont want to buy another one, and it would be a lot more work to run the coax through the wing.
 
Thanks Bill, that sure looks like the easy way to do things----I may just "borrow" that idea.

Only issue is that I was not planning on mounting mine that far back, and IIRC, there is a "J" stiffener ahead of his mounting location.
 
Yep.

Mike, mine's mounted in line with the leading edge of the stab, under the fuse, very similar to that one and is out of the way...no poke in the eyes. Works well.

Best,
 
Mike,
Be careful mounting it to far forward. This is a dipole antenna that is horizontally polarized. It is not meant to have a ground plane so close to the horizontal plane. Normally these are mounted on the vert stab dissecting it in the vert plane. Also, make sure you have the a balun connected correctly. the impedance without the balun is around 150 ohms and the balun transforms that to 50 ohms, which is what the coax and radio like to see. From a performance and electrical standpoint, the preferred mount would be in the vert stab fairing. It would also keep the pointy ends away from eyes. I believe that Sean retrofitted his in this manor.
Bill
 
Bill.Peyton said:
Mike,
Be careful mounting it to far forward. This is a dipole antenna that is horizontally polarized. It is not meant to have a ground plane so close to the horizontal plane.
Click to expand...

Good info, I was not aware of this----my radio knowledge is pretty much limited to twisting knobs.

Bill.Peyton said:
Normally these are mounted on the vert stab dissecting it in the vert plane. Also, make sure you have the a balun connected correctly. the impedance without the balun is around 150 ohms and the balun transforms that to 50 ohms, which is what the coax and radio like to see.

I believe that Sean retrofitted his in this manor.

Bill
Click to expand...

Got the balun thing under control, and I agree that top of the stab would be the best place to mount the antenna, but I am just not seeing that particular task as being something worth the effort. If I was still building the stab, then it would be a no-brainer.

Sean who??
 
The Rami has the white plastic block right? I'm thinking you could bolt right through that into the lower empennage skin with a decent doubler inside? Then glass up a fairing lump to fit over the block. Maybe lay up a flat bottom saddle on the curved skin first and bolt through that?
 
No white plastic block, just the normal round hockey puck.

It has two threaded studs for coax connections, not a BNC connector.

58635924-av-12.jpg
 
You must log in or register to reply here.
Back
Top