Carri Er Oscillator; Passband Tuning Oscillator; Counter Reference Oscillator; Passband Tuning Indicator - Swann CUBIC ASTRO 102 BX Service Manual

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~~M~!~ATIONB
SIVAIfI
DIVISIDN
CARRIER OSCILLATOR ADJUSTMENT
Conneet the microphone to the MIC/KEY jack on the front panel. Conneet
the osci11oscope probe to the emitter of Ql17 on the exciter board. Key the
unit with the microphone button and adjust transformer Tl05 on the exciter
board for a maximum indication on the osci11oscope of approximately 1 V p-p.
Unkey the unit. Disconneet the oscilliscope probe and reconnect the freq-
uency counter to the same point. Key the unit and make adjustments accord-
ing to the following table, in the order listed.
MODE
LSB
USB
CW
CAPACITOR
C194
C197
C199
FREQUENCY
9.00000 MHz ±10 Hz
9.00330 MHz±lO Hz
9.00250 MHz ±10 Hz
Unkey the unit and disconneet the frequency counter and microphone.
PASSBAND TUNING OSCILLATOR AillUSTMENT
Measure the voltage at the center leg of the PASSBAND tuning control
(RI03B, rear section) and adjust the PASSBAND control for 5.25 ± 0.05 V DC.
Conneet the frequency counter to G2 of Ql13 on the exciter board and
adjust the PBT trimmer capacitor (C206) for a frequency of 22.80165 MHz ± 20
Hz.
Vary
the PASSBAND control from fully counterclockwise to fully clock-
wise and note that the PBT oscillator has a frequency range greater than 3.6
kHz.
Disconneet the frequency counter and reconnect the oscilloscape probe
to the same point. Adjust coil Tl06 for maximum indication on the oscillo-
scope screen, approximately 1.5 V p-p. Disconneet the osci11oscope probe.
COUNTER REFERENCE OSCILLATOR ADJUSTMENT
Remove the cover from the units frequency counter and conneet the shop
frequency counter to pin 9 of Ul14 on the counter board. Adjust the refer-
ence oscillator trimmer (CIIO) for a frequency of1.31072 MHz ± 2 Hz. Dis-
conneet the frequency counter and reinstall the counter cover.
PASSBAND TUNING INDICATOR ADJUS'IMENT
Set the PASSBAND contr01 to its 12 o'clock position and adjust the A-D
RANGE trimpot (R166) on the audio board so that all eight PASSBAND KHZ li-
ghts are on.
PTO AND RIT ADJUSTMENT
Set the MODE switch to LSB, and the BAND switch to 20, turnthe RIT to
its off position (RIT light extinguished) and adjust PTO A for a display
frequency of 14270.0. Switch the MODE switch to USB, and if the display
frequency changes, adjust the USB SHIFT trimmer (c608) on PTO A so that
there is no change inthe display frequency when shifting between LSB and
USB modes.
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