wireless mics
Okay after reading the original post, I am a little confused. I have worked with some old wireless systems, but I have never seen any that had an 1/8th inch output. In all wireless systems there are four very important parts. Let's start with the mic capsule. The mic capsule is the actual
microphone. These do go bad faster than one thinks. This is the part that is often "sweated out" during a performance. If sweat gets into it, it will go down and sound bad until it has time to dry out. Some of the newer capsules are better at this. The
Sennheiser MKII gold is the industry standard and has a high resistance to sweat. I am a big fan of the Countryman Isomax B6. It is the smallest capsule on the market, it is cheaper than the MKII and it is superior in sweat resistance. It just doesn't sound quite as natural as the MKII.
The second part is the transmitter this is the pack that is generally worn on the waste, thigh, chest, or back. This
unit requires a battery to
send the signal. In active musicals, it is good practice to place the transmitter in a nonlubricated condom. Sweat can also destroy these units. In ways to cut production costs, I have heard of some theatres switching to plastic bags. But for my money the condom is the way to go. This
unit also has an antenna. The antenna have occasion to go bad also.
The third part is the reciever. This is usually stationed at the mix position. This is where the signal is recieved and sent to the mixing
console. In larger houses you sometimes have to run antenna extensions to above the
stage.
And then there is the
power supply. Pretty self explanatory. All of these have to be in working properly to get a good signal.
In your post you say you only had enough batteries to test one, but did you try bouncing your good batteries to the other units?
Hope this helps a lil'