On the frequency, It depends on which type of drive you get. Some are just amplifiers that drive the motors on robots, which obtain the input signal from a computer.You have to search around for these as they are basically surplus equipment. The all in one units typically have their own frequency generator that is built into the unit. (ie TB WOODS make some, ther are lower cost ones alos but I don't remember the manes o the companies)
Most can be set by a keypad or via an external resistor (actually a voltage). If you wanted to you could have a computer with a DAC board act like the resistor but for adjustalbe fixed frequency operation a multi turn resistor is the easiest thing to use.
On the tube drive, I don't remember what type of signal is used to drive the tubes. I seem to recall that is was pulsed RF but I might be wrong. If it is just low frequency AC then you can use a step up transformer but the range of usable frequencies will be limited by the transformer characteritics.
If it pulsed RF, look for a old ham radio transciever. Most would output at least 100 watts, which is easily enough to light a tube and if you find a unit that had AM (not all had/have this) you can put what ever waveform you like to modulate the power. If it just want a on off pulse, all of these units can do this in CW mode.
On the whole rife topic, It appears that it works for some people and I can't and won't argue with success, I am however at a loss as to how it works.
I don't buy the vibrational frequency explaination due to the fact that it does not hold up to fundimental physics that would be encountered in the apparent successfull application of the treatment.
In other words, the different types treatment (coil, lamp, e-field) and the frequency of operation of these as well as the tissue penetration are quite different for each of these exposure methods. However people claim that each works. In addition, the ability to fragment the bacteria by EM excitation is highly dependant on what matrix the bacteria is located in. In tissue it is more tightly bound and less free to vibrate than it would be in serum, yet the technique appears to work at a specific frequency regardless of target organ.
Also, there are lists of "resonant" frequencies for various viruses and bacteria and the treatment time is so short, why not just sweep the whole spectrum with a sweep genrator, that way you get then all in one shot.
Bottom line is that it appears that something is going on but the explainations to date are insufficient to explain it in a manner that matches experience. I dont think that it is placebo effect, so I assume that it something that nobody has figured out yet, its basically just a bunch of experimental observations.
The explaination is very important in that once a model is derived, the techniques should be able to be optimized and deployed on a commercial scale. If Rife does indeed work and the modality of operation is figured out it is not inconceivable that you could stick sick people into a MRI like device and fix up thier problems. Such a device would not even need FDA approval as this would be the jursidiction of the FCC.
Unfortunately at this time this is only seen in the science fiction movies....