hi all,
john wrote...
<snip>
> He insisted that the oscillator could not have a parasite
> simultaneously and still work on the designed frequency. I said it could,
> that it could be simultaneously be making "non-harmonic" energy that could
> break things, or created uneven heating and hot spots. Also arcs around the
> tube and output electrodes. Does anyone have evidence to refute such
> advice? That an oscillator can, by nature, only work on one frequency at a
> time?And I don't mean XTAL oscillators but LC circuits and tubes.
well, i had a tv-horizontal output tube amp once (tetrode: home brew)
that sat quietly and quiescently with no drive. it was not an
oscillator. when i applied 10m drive, it would go "non-linear" at a
threshold drive level, and put out 2 frequencies, 28 (same as input)
and about 70MHz. (not a harmonic of 28) when i took the drive off,
the 28 went away, but the 70 stayed! now it was an oscillator. i had
to remove screen and plate potentials to calm it down. reapply
voltage... ok. reapply drive, and the same thing would happen again!
now that's a parasite: one which depended on the tube (and
associated circuitry, and applied voltages) *and* the presence of
drive on 10 meters. i never tamed it, tho' i confess i didn't try
very hard.
73,
George T. Daughters, K6GT
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