If you are serious, you will eventually want to join, but non-members can access many of the services, albeit at a higher cost. Unfortunately, there are no archives to research, but the continuing discussions are extensive and may provide the information you are seeking. You can also post an inquiry, but please do read the FAQ first. This link will take you to a complete list of all of the newly assigned digital television frequencies. This list is invaluable if you are trying to coordinate wireless microphone frequencies to an open channel.
Wireless microphones share the same frequencies as television transmitters.