Question? As the emission of a tube drops, does the efficiency % (ratio of
output to input) stay relatively constant? If the plate current simply
decreases while the efficiency remains constant, then a simple way of comparing
two tubes in a parallel amplifier would be to measure exhaust temperature of
each stack.
Even if the efficiency decreased a bit, the increase in exhaust temperature
should not offset the decrease in plate input. Thus a weak tube would always
have a lower exhaust temperature than a good one.
Do any commercial amplifiers monitor exhaust temperature for more than simply
determining if the blower is working (like the Collins 30S-1)? Perhaps
efficiency could be estimated with such a temperature probe.
Not sure if the digital temperature probes would be affected by the strong rf
field above the tube - even if outside of the amplifier cabinet.
Colin K7FM
--- COLIN LAMB
- k7fm@teleport.com
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