[Robert Paterson]

Hi John,
Just came across your post, not sure if you got it sorted, but if not hope the following helps.
I’ve got 3 of these systems and have had no problems with them at all. They are quieter than a lot of the top manufacturers lower end products, e.g. sennheiser G2. If you google the Sennheiser EK3041, you may notice some similarities! Mipro are the OEM manufacturer for Beyerdynamic radios, and I know people who regularly use 32 of the ACT rackmount systems for musicals, completely interference free.
The principle of the ACT system is that it can scan the frequency band it is operating on, and will then select an interference free frequency (you can also manually select a frequency by selecting a group, then a channel). Once the frequency is selected, press the ACT button on the receiver, whilst holding a powered up transmitter with the ACT window (looks a bit like an IR window, and has ACT printed near it) within 20cm of the receiver ACT button. This will set the transmitter to the same frequency as the receiver, and hey presto!!!
If you would like me to, I can scan the manuals and e-mail them off to you. I also have the frequency chart, but this would only be relevant for the UK/Ireland.

All the best.