What's new
Van's Air Force

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

Forward transponder antenna mount

9erDriver

Well Known Member
Thought I would share an idea for mounting the transponder antenna up front. Like many 8 builders I struggled with placement of this antenna so as to keep the proper distance from com and adsb antennas, and also wanted to keep the xpdr cable run to a minimum. Problem is that pesky false floor.

So I cut a 2" hole to access the bottom skin from inside, mounted the antenna, and then finished it off with a cover plate held on by #8 nut plates fastened with flush mount pop rivets.

I did the installation on the right side of the plane since I did not extend the forward baggage compartment to the floor, but looking at the plans, I think the concept would work on 'normal' 8's and 8A's on the left side provided you can avoid the fuel plumbing. I found this antenna mounting location to work really well on my 9.

sept13b.jpg

sept13.jpg

sept13a.jpg
 
Transponder ant

I mounted mine ( taildragger) on a bracket screwed across the LH gear access on the bottom of the fuselage .
The cable goes down the gear tower thru a 1/4" hole to the ant . The cover plate has a 1/4" hole for the ant to protrude ,

Can email pics .

Tom
 
Due to the proximity of the antenna to the edge of the ground plane I would expect certain bearings to have poor operation.
 
I mounted mine on the belly skin just in between the fuse and right wing, and just aft of the aft wing spar fixture. My comm antenna is on left fuse belly under the rear passenger foot well, it gives about 3 feet in between them.

Bird
 
Due to the proximity of the antenna to the edge of the ground plane I would expect certain bearings to have poor operation.

My RV9A with similar mounting location passed several bi-annual IFR transponder checks with flying colors. ATC never had a problem seeing my xpdr in almost 1000 hours of flight.
 
Back
Top