>
>Looking for some wisdom... Need to mount a couple of Jennings CVCJ type
>vacuum variables and have never seen a close-up view of the proper way to
>physically mount them.
? Vacuum variable capacitor plates are made of soft copper. The plates
are so soft that they are affected by gravity. At the Jennings factory,
vacuum capacitors are connected to an oscillator/frequency counter, and
rotated horizontally to evaluate plate concentricity. . If the plates are
concentric, the frequency of the oscillator will not change as the
capacitor is rotated . If it is necessary to align the plates, the
device under test is discretely bumped on a cushion and retested. In
their catalogue, Jennings says the best way to mount vac. variables is
vertically. This quite obviously takes a right-angle drive and a drive
shaft to the turns-counter on the front panel. / (Groth turns counters
are ideally suited for this arrangement. - Multronics/Cardwell makes an
ideal right-angle drive that replaces the collet on the end of the
vacuum-variable tuning shaft). / . . Vertical mounting uses less
chassis space than horizontal mounting. However, vertical mtg. typically
requires a 4 to 5 inch deep chassis. On the other hand, for a tetrode
with handles, a deeper chassis makes the job of finding a suitable
filament-transformer easier. // free, unsolicited advice:. Test all
vacuum components on a high-pot before installation. I have seen new,
out of the factory carton, vacuum variable capacigors that had been in
storage for a few years, which had partially lost their vacuums due to a
defect in the seals.
- later, Bill
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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