Transponder antenna location considerations

[MS19087]

I am installing this on my 9A. I have read all (i think all) of the posts on this topic - it appears that 4 major considerations exist . . . 36" minimum from transceiver, maximum length of coax run (8' or so using RG400), shadowing (A models only?), and distance from COMM antenna. So it is easier ruling out where it can't go - i.e. behind baggage bulkhead due to coax length, etc.

I have come up with a location (on the belly - under pilots seat) which meets most considerations and it leaves the antenna approx 24" from left gear leg, 22" from COMM antenna; approx 8' coax run - my question is . . . is 24" and 22" distance enough to avoid any issues??? As always . . . thanks for your input. Mark

[Radomir]

Mine's forward.. right next to the fuel vent fitting (just aft of firewall). It works.. and it works great... No idea what all those theories say it should be doing, but it works just fine

[Bavafa]

I have mine right aft of the firewall exactly in the middle (between the two vents) and have never had any issues with transponder. I have the Garmin 330 and TIS reception is much better then my buddy's, I pick up traffic as soon as I am about 200-300 feet AGL.

Mehrdad
RV7A- IO360M1B

[Rick_A]

Not sure where you got the coax length number (maybe I should know) I don't recall the 8' limit. I put my GTX327 antenna behind the baggage bulkhead (offset to the right) and it works fine.

I've got one comm antenna just aft of the main spar near the center line and a 2nd comm antenna about 1/2 way between the baggage bulkhead and the next bulkhead aft (offset to the left).

[Mel]

I also have my xponder ant aft of the baggage bulkhead and it's been working fine for over 16 years.