Low-V Testing 250TH, 100TH

[David Stinson]

I recently acquired some more 250THs and 100THs.
I've got the filaments running for 24 hours to
restore emission and to drive off long storage
gas accumulation.  Have three sockets with the filament
leads connected in series and fed by 14 VDC.
I can tie the grid leads to +14 V to forward-bias
the tubes and read 12-18 MA current on a meter connected
between the plate caps and +14V.  Just using the meter's
internals for a load at this stage, since I didn't
expect high current.

My question is-- Can this low-voltage data point
or a few low-voltage measurements be
extrapolated to performance at designed voltages?
I'm wondering if I could use such a simple test
to "match" pairs.  I think it unlikely but
thought I'd ask if anyone has any insight on this.

If not, what is the simplest way to test these,
short of building a transmitter?

Thanks and 73,
Dave Stinson AB5S
arc5 at ix.netcom.com

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