Transponder coax

As you may have seen from past postings of mine, I have been a big fan of the use of Andrew's FSJ1-50 heliax for our aircraft's radios. My friend Rob Cherney has done an interesting analysis of comparative data for RG58, RG400, and FSJ1-50 in terms of received and transmitted signal levels. He will be publishing the report in an up-coming CSA, Central States Assoc. canard newsletter. I have his pdf file, but I don't know how to put it on this forum, so if you contact me at [email protected] I will be happy to send it to you.

Andrews heliax is great stuff, especially for microwave frequencies, but what a incredible royal pain it is to work with. Good old RG-142 with the solid core or RG-400 is sooooooo much easier to put a commodity BNC connector on, and works just perfectly fine for a transponder in a small aircraft. Yes, a laboratory instrument will show that the heliax is better, but ATC's radar and your transponder won't know the difference for that 6-8' run to the transponder antenna. I'll save the heliax for 250' runs up the side of an antenna tower

I must have missed something. My coax came from Radio Shack and the guy who tested my transponder prior to my first flight said it was one of the strongest he had ever tested. So far so good and no interference with any of my other electronics.