[Amps] Cell phones, digital cameras and RF

[Fuqua, Bill L]

  How many times have you taken a picture of an amplifier tube glowing very red with the cover removed and with a cell phone or digital camera?
I have done it a number of times and yet the relatively intense RF electric fields seem to have no effect. I have taken photos of my 4-1000A amp with
bright red plate and probably 6 or 7kV p-p rf only a foot away or so.
They must be very well shielded!
  73
Bill wa4lav