Hi Terry,
I do believe that there are some differerences in the frequencies that are used between a beam device and a pad device, I may be wrong about this but I have somefrequency specs that I downloaded a couple of weeks ago and some refer to "beam" and others to "pad". I haven't had time to study and cross-reference them yet.
You mentioned the frequency 666 Hz, ( ) this one seems to pop up quite a lot, also used in Pain Manegment.
2128 Hz also comes in to play quite a lot for cancer treatment but I think that this is one of Rife's original frequencies.
Kind regards