.::4PR-1000A VTTC::.
This project began with the acquisition of a pulled YU-204 vacuum
tube manufactured right here in Easton Pennsylvania. It is the same
as a 4PR-1000A tube, the pulse-rated version of the 4-1000 tube.
The tube is rated at 1000W. The specs and characteristic curves can
be found here:
At first, I was having trouble getting it to even oscillate. The
tube is rated for 10KVDC nominal, and one MOT was not enough. I
decided to go with two MOTs in series for 5KVAC. This still was not
enough. I was and still am getting help from John Freau. He looked
at the specs and the curves and suggested biasing the screen grid
through a resistor, which would make the tube behave like there is
more voltage on the plate. Since I was using 2 MOTs, I at first
used 3 MO caps to ballast the supply. In the end, this kept it from
oscillating. I bypassed the caps and got 4" - 5" arcs. Not bad
considering this is my first attempt at a VTTC. Further tuning has
yielded 6" arcs, but it is capable of much more, possibly 2 to 3
feet.
Copyright 2003 Phalenor High Voltage Labs
