[AMRadio] Testing big tubes

[Bill Smith]

I have the article of the GE publication and while it does give ideas of how
to test power tubes, the jigs look just as elaborate as the equipment in
which the tube would be used.  Given the fact that tube testing is at best a
test for shorts and emission, actual service is probably more realistic in
any event, and no doubt more so for power tubes.

Running tube characteristic curves does sound interesting, but think it
would take quite an elaborate high-voltage switching scheme, even if only
grid voltages were controlled.  I recall a unijunction based project I built
once from a Popular Electronics project to generate transistor
characteristic curves on a scope.  A pair of unijunctions were used, one as
an oscillator to generate a staircase, the other to periodically reset the
staircase to zero.  It was very simple and seemed to work quite well.  I
suppose that approach could be used, with DC amplifiers to increase the
voltages to be compatible with tube operation.