List,
Wrote <Some on this list mentioned having had less-than-optimal performance
with their HP 10811 series oscillators. James Miller G3RUH made a slight
mention of optimizing performance by readjusting the set point temperature in
one of his phase detector articles. He said though time consuming the results
were worth the effort.
Replied: <Regardless of isolated anecdotal data on one oscillator, it is
probably not advisable to change the set point.
Answer: Agree. My comments were made about someone with a “wonky” oscillator
that that this MIGHT be part of the problem.
Replied: The majority of 10811 crystals do NOT have a turnover, only a region
of low tempco around 82 degrees.
Answer: I respectfully disagree. First isn’t a region of low tempco another
way of saying turning point? Semantics aside, I believe that they do have a
turning point that is selected. This is why. HP selects 41 separate
resistance values to obtain 41 different oven temperatures between 80.0C to
84.0 C in .1 degree increments. Now if that isn’t finding a turning point I
don’t know what is.
I believe that is why they say if the oscillator fails it needs to be repaired
at the factory.
Wrote: <Instead of that, change the circuit to B-mode and optimize the heat
between the two heater resistors for maximum thermal gain (you should be able
to get 1000). Then change the circuit back to normal.
Answer: I have no idea B-mode is. Would you please expand on it and how to do
it? It could be very useful.
Regards,
Perrier
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