Peter,
Radio is somewhat of a grey area, allocated frequency band are set in legislation by the government of individual countries and not by the likes of the FRA or the RFL.
Officialy it should be 75 Mhz. You could use 40Mhz in the US, (It has been done) BUT if the agents the FCC (Federal Comunication Commision) turn up to the event, slap the cuffs on you and drag you off to Guantanamo Bay then you are on your own!!! :wink:
You may want to consider 2.4 Ghz as a frequency that would be acceptable virtualy world wide.

Possibly David C. may be able to clarify the position further in relation to this event.

(Message edited by scorpion on September 16, 2006)