Here we go. We use the Honeywell/Sperry 4066010-90X series TCAS computers, with P/N 7514081-901 Directional antenna, and P/N DM1601354-001 Omni antenna (on some installations). Directional antennas can be checked: J1 - 850 to 1200 Ohms, J2 - 6500 to 9950 Ohms, J3 - 3250 to 4950 Ohms, J4 - 1650 to 2450 Ohms, all measured center conductor to shield of the antenna connector. A similiar reference had J1 - 1k +-100, J2 - 8k +-800, J3 - 4k +-400, J4 - 2k +-200. The cables should have at least 50k Ohms resistance, conductor to shield. Omni antenna should be less than 50 Ohms, conductor to shield, with examples in stores reading about 1 Ohm on my favorite Fluke.
Antennas should have 0.1 Ohm bonding to structure, and our maintenance manual calls for the connections at the antennas to be covered in Dow Corning #4 compound to prevent moisture entry.
I haven't played with the ATC601A test set, which we have at some stations, but I am familiar with the TIC-49 series. They work fairly well (with fresh batteries)for quantifying performance, and will read output wattage, frequency stability and sensitivity. I have found I have to put the antenna sleeves (or boots) over the ATC antenna's a few time to get optimun readings on Mode S, usually getting best readings when the cover is centered over the antenna. Like most test equipment, you have to play with it a bit to get comfortable with the procedure, so you can trust it.
Buy me a beer sometime.
[This message has been edited by redtail (edited 15 April 2000).]