"Scott Dorsey" wrote in message


What is worse is that some of the finest tubes made are TV
and
military designs that you can't give away today. Those
Raytheon subminis have some of the best high-gain
low-microphonic performance of anything around, and people
are
using them as jewelry because there's no demand for them
for
anything else.

My radars had literally 100's of 'em, all neatly wired to
carefully swaged silver-plated posts on FRP circuit boards,
clipped to heat sinks that were mounted on the back of the
cakepan-like chassis. I believe they were rated for 10,000
hour MTBF. My largest radar had over 400 of them, and it
dutifully went down about once every 24 hours. Do the math!

They subminis pretty well duplicated the common
signal-handling tubes of the day. There was one that was
12AX7-like, another that was 12AU7-like, others that were
like 6AU6s, and even a 6AL5 work-alike. The biggest
concentration of them in one chassis was a triple IF strip
with about 10 transformer IF stages per channel.

Perhaps the most impressive item in teh system was the
spectrum analyzer. Balanced mixers converted three adjoining
frequency ranges of the inbound signal to the same range of
intermediate frequencies which passed through three
identical sets of additional tuned circuits and rectifiers
to provide a fast-response spectrum analysis of the inbound
signal as the antenna rotated.