[BC] unreliable old equipment query

[David Senft]

Respecting unreliable old equipment, here's my list from the early 60's.
RCA TT11AH TV transmitter: The aural exciter had a chain of frequency
dividers that compared the master oscillator with a crystal-controlled
reference oscillator. The tubes in the "counter chain" worked very hard and
failed often. I would switch off the reference control-voltage and "hot
swap" tubes from a tube checker to test them during broadcast hours. There
was an FM version of this exciter that was so micro-phonic that during
maintenance "off-hours" the engineers used it as a studio-intercom by
speaking to it. Another brand of FM exciter would drift 1000 Hz for every
degree of ambient temperature change, -a thermometer that measured in
1000ths of a degree. The TT11AH Tx had a wall of mercury vapor rectifiers in
the power-supply cubicle that were also fun. Once the blower quit and the
air-sensor switch went out in sympathy. The melting solder from the 6166
power tubes provided a convenient "crowbar" shut-down. (We sent the tubes to
Eimac for refurbishing, - they were OK.) The MTBF of the TT11AH was about 30
days. Having no tubes, the Gates RDC-10 remote control worked flawlessly
until needed. The Gates BC-1T AM Tx originally used horizontally-mounted
6BG6 TV receiver tubes that were obsolete before the Tx was designed. They
would sag and short, burning up the p/c board with them. We replaced them
with vertically-mounted 807's. No problems once most of the original
transformers and chokes failed. That Tx ran for some 20 yrs as main and 25
years as a standby. The RCA TVM-1A microwave. Nuff said. Any tube-type TV
equipment with the logo EMI. Compared with a Conrac, their video monitor had
three times the components yet didn't work as well. By 1966 I was convinced
to focus on radio. Still am. 
D.