🚀 go-pugleaf

In article <3574@sdcsvax.UCSD.EDU> brian@sdcsvax.UCSD.EDU (Brian Kantor) writes:
>
>It was explained to me that the phantastron tube was basically set up
>so that an electron beam travelled from cathode to anode as in most
>tubes, but that there was a large magnet clamped around the tube to
>force the beam into a helical path to make it longer.  Apparently
>there were a set of electrodes that stretched or compressed the length
>of the helix, thus changing the time it took for the electron beam to
>traverse the tube, thus phase modulating the signal.
>
What you describe sounds similar to what I think is called the "serrodyne"
effect (spelling from memory). I once worked on a system which used
a travelling wave tube to modulate a (GHz) signal like this. I don't recall
magnets, but there was a sawtooth input (<10Khz) to the helix, as you
increased the amplitude, the signal freqency reduced. ( My instructor gave
strict instructions that the helix was never to be disconnected or
the TWT would blow. I subsequently found out that the TWiT's cost
over 1K pounds. :-) )