The preamp for a PMT or Neutron proportional tube has to be pretty S--- hot! This is not a super big issue in the current market due to ultra fast DC-video op amps and the like, but it used to be.
I wish I knew more about the counter-preamp you are talking about Steve.
A BF3 tube preamp needs to sniff out and amplifiy a millivolt or so of signal riding on about 1500 volts or more DC which is most often genrated by some sort of switching supply (noisy). This first stage of amplification must take you from a milivolt or two to 200 mv or more. Rise times must be ultra rapid in the 10's of nanoseconds. A good digital storage O'scope will help the amateur dope out what kind of signal he is dealing with. Spike pulses from some PMTs can be well under 1 usec, some as short as 100 nanoseconds total! This means short cable lengths- sensor to preamp, superb shielding and line termination.
Since we are expecting no more than a few pulses per second maximum in fusor work and little coincidence, a pulse discriminator/stretcher would be a nice idea. With a 10usec pulse width you could send your signal for further processing over 20 foot audio cables.
Lots of ideas, little time to mechanize them.
Richard Hull
Created on Tuesday, April 17, 2001 5:32 PM EDT by Richard Hull