I have two Welch model 2639 electron diffraction tubes (circa 1965) and
the corresponding power supplies (2639A), and the supplies are starting
to act wonky. One unit refuses to keep the filament current below 30
mA, and any adjustment to the accelerating voltage runs the filament
current up to around 100 mA. The other unit is showing a fluctuating
accelerating voltage (+/- .2 kV), and occasionally the spot becomes a
diagonal line that crosses almost the entire screen.
Does anybody have a copy of the schematics for the power supply? I
would really love to fix these units up as they are an excellent lab.
Schematics would earn my eternal (or lifelong-YMMV) gratitude.
Also, does anyone have any ideas regarding alternatives, other than
Tel-Atomic?
Thanks in advance.
Mr. Scott E. Whitmire
Supervisor of Instructional Laboratories
Department of Physics
The University at Buffalo
304 Fronczak Hall
Buffalo, NY 14260-1500
716-645-2017 X201 http://www.physics.buffalo.edu/