[Milsurplus] More on BC375 Tube Subbing

[David Stinson]

While getting the SCR-287 ready for W5E in April, I subbed
an 838 triode in both the oscillator and power amplifier stages of the 375.
The 838 physically looks like the 211, with a more robust mechanical
structure. It costs less than half what one would pay for a NOS 211.

The 838 is a "zero bias" triode amplifier, while the 211
is a more conventional triode.  It also has a somewhat different
interelectrode capacitance.  After re-neutralizing the PA,
the 838 seemed to work just fine in the final.
In the OSC stage, it appeared to be somewhat less
stable, but I didn't really give it a proper warm-up.*

Does anyone have any thoughts on using this tube
as a lower-cost substitute for the VT-4 / 211?

73 Dave S.

* as an aside- once the 375 had run for a couple of hours
prior to the W5E event, it became quite frequency stable on 3880 KC.
After two hours, I never had to correct it again.
But then, I did hand-pick the oscillator 211 for stability,
so that may have been a factor.