This probably won't help this problem, but I'll share this experience with you guys.
I'm mixing a show with 22 radios now, 12 of which the
theatre borrowed from another local
theatre. I was having all kinds of dropout problems most particularly with two radios in that rack, and to a lesser degree the other 10 in that rack.
Sennheiser SAS232 splitter, omni vertical antennas, two 25-ft lengths of RG-58. Set up at the back of the
theatre. I tried several things to fix it:
- check IM3 calculations in SIFM (all good except for a few 3-Tx IM3s)
- decrease the
line losses in the 58 (shorten one, replace one with LMR-400)
- move one remote antenna very close to
stage with 100 feet of 400
- check antenna connections on the transmitters involved
No dice. I was fiddling around with RF connections at the rack with one of the problem radios on and happened to watch the RF bars as I pulled the
coax out (to put a vertical directly on it). Signal went up nearly full scale with no antenna. Aha!, it's the antenna splitter.
Turns out this splitter has cavity filters in it, and the radios from the rack are in two nonadjacent 12-meg splits, and the splitter outputs were all kinds of cross-wired. I ripped the rack apart and rebuilt it right, correct cavity filter output to correct split of receiver, and everything is rock solid.
The only problem I had was that this also made the TV station that was co-channel with one of the radios also jump up full scale. Switching that pair of link radios to a
clear frequency cleared that right up.
So, if you have antenna splitters with filtering in them, make sure you're not trying to
plug them into receivers that are out of the splitter passband.