OK, here are some preliminary results. First, the good news: none of the mics conflict with one another. This is important and a really good thing. However, you have two definite conflicts with local TV stations and one future one. The mic on 192.75 conflicts with
channel 10, and the mic on 733.0 conflicts with
channel 57 - so I wouldn't be surprised if these ones give you a fair amount of trouble. You will start having trouble with the mic on 189.0 soon when
channel 9 comes online. Other than that, I see no other major issues other than the heating
system which you mention. Could you elaborate on how that affects the mics please?
Now that all of the frequencies check out, let's look at some ways to improve reception. Due to the fact that none of the
TOA mics have diversity reception (that is, two antennas), you may very well end up with dropouts at certain points on
stage. However, we should be able to limit the number of dropouts by repositioning the receivers. The first thing I would do is move all of the receivers down to the
stage level. This will help to
shield the receivers from the TV channels and other interference. Next, reposition the antennas on the receivers so that the
TOA ones are vertical, and the A-T ones are at a 45 degree angle, pointing away from each other. This will make them more sensitive to signals coming from the
stage. By the way, have any of the antennas been bent, cut, or otherwise damaged? That could be a definite cause of reduced reception. ANother thing to remember is that if you have antennas of different length on the
TOA systems, the longer antennas go with the lower frequencies if it is possible to do so.
If after taking these steps you still are having trouble with dropouts, have someone systematically pace the
stage with a troublesome mic while you watch the RF readouts on the receivers (I know the A-T one has a readout, and I can't tell if the
TOA has one). While the person with the mic keeps walking and talking, move the receivers around backstage until you find a place where the
system does not
drop out. You may end up with some arcane locations, but if it works, it's better than nothing.
If you still cannot get decent reception with the equipment, it may simply need to be replaced or serviced. You should seriously consider replacing the
TOA mic systems if you can get the money to do so. I would replace them with either the
Shure SLX series or the
Sennheiser EW G2 100 series. Both of these systems are reliable and will work well for you. Be sure when you buy them that the frequency range you get has the most channels available.
The A-T systems are fairly new and should give you little to no trouble, with the exception of the one on 733.0. Give A-T a
call and see if they would be willing to retune this to another frequency which is
clear in your area.
By the way, I'm curious to know when these systems were bought.
Good luck, and keep me updated as to how things are working!