Luke,

 

I had a setup very similar to what you describe in our 320 with the AAE antenna mounted on the fuselage side just ahead of the h stab. We would drop radar contact if we were heading directly toward or directly away from the radar site. I believe that there is a null lobe on the side of these antennae, possibly due to their thinness. I solved the problem by using a standard rod type transponder antenna. I mounted it on an aluminum ground plane, stuck it under the passenger seat and drilled a little hole in the belly for it to stick through. This seems to have solved all of our previous directional problems.

 

Bill Harrelson

N5ZQ 320 1,800 hrs

N6ZQ  IV under construction

 

 

 

 

I am trying to diagnose an intermittent problem with my transponder.  I believe it is my antenna location and would like to know where most people mount their antenna's on 320/360's.  Mine was located on an aluminum bracket (for the ground plane) on the middle to top right side of the inside aft fuselage tunnel.  Slightly above and behind the aft elevator bellcrank.  I was getting problems with ATC lossing me, usually when I was pointed towards the radar site.  I figured the antenna was located too high and that the engine and prop were blocking it.  I bought the AAE composite transponder antenna so I could temporarily place it in different spots and test it.  I mounted this one farther aft and lower in the tail and it seemed to work well except, descending into and climbing out of KHEF, they lost me from 8000 down to 2000.  Considering I was pointed opposite directions, the engine should not have blocked it both times.  I have a KT76A transponder.  I would like to know what are the best places people have found to internally mount the antenna.  My comm antenna is mounted on the belly behind the rear bulkhead and the vor is internal under the baggage compartment.  Thanks in advance for you help.

Luke Alcorn