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crystal from stage to stage and test point to test point; a
point should be reached where a test point voltage does not
vary.
This should be the last properly operating stage.
Im-
mediately following the point where the test point voltage is
not varying.
An intermittent carrier can be caused by most
anything.
A bad tube,
capacitor,
resistor or loose connection
or an intermittent short.
o
o
OSCILLATION
It is an almost unheard of condition for a frequency multiplier
stage to oscillate since frequencies found in the grid circuit
are different from frequencies found in the plate circuit.
It
is within the realm of possibility, however.
If an oscillation
should occur,
it will probably be traced to the final amplifier
stage, V115.
This stage is self neutralizing and will probably
not cause any trouble as long as the shields oVer the coils are
tightly in place and all connections are tight.
A condition somewhat akin to oscillation has been noted while
using pulse circuitry similar to that in this exciter unit.
A
leaky capacitor or intermittent connection in the pulse circuitry
can cause the frequency multiplier stages to " fire" off at their
resonant frequency.
This oscillation will be damped and only
occurs momentarily but may be aggravating.
CARRIER OFF FREQUENCY
When the carrier is consistently too far removed from proper
center frequency, the trouble can be traced directly to the
oscillator stage.
This could be due to the oven thermostat
sticking and causing the crystal to overheat or could be due •
to the oven not heating at all.
If the thermostat is sticking,
pilot lamp £ 101 will be on all the time provided it is not
burned out.
If the oVen is not heating at all,
the pilot
lamp should not light.
Some crystals will age and drift off frequency after a length
of time.
Replacement of the crystal is the only solution here.
A change of w
.
lue of almost any component in the oscillator
stage V101 could also cause the carrier frequency to deviate.
Problems associated with modulation of the carrier will nclirbe
discussed and some possible remedies and trouble shooting hints
suggested.
Under this category,
sub- division might be as
follows:
-22-
M6095 Exciter
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