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ALIGNMENT PROCEDURE
NOTE:
2.
To reset the presets, press the AM FM and STORE buttons simultaneously for three seconds.
FM SECTION
A.
PREPARATION
1.
Set stereo modulator to mono mode with 1kHz modulating signal unless otherwise stated.
2.
Set signal generator to FM mode with 75kHz deviation.
3.
Store the following frequencies: 98MHz, 87.5MHz, 108MHz, 90MHz, and 106MHz.
4.
Note: RF levels are open circuit voltages of signal generator with 75 ohms output impedance.
B. OSCILLATOR TUNING VOLTAGE
1.
Connect DVM between TP6 and ground.
2.
Tune to 87.5MHz and check DVM for a reading of 3VDC +0.5V.
3.
Tune to 108MHz and check DVM for a reading of 20.5VDC +0.5V.
if either of the above is out of tolerance, adjust FE4 (oscillator coil) until both readings are
within tolerance.
Connect DVM between TP4 (VA) and TP5 (VB).
Apply 10.7MHz (90dBu) via 1Kohm resistor to TP7.
Adjust L8 for OVDC +50mV reading on DVM.
Adjust L9 until minimum THD is achieved at audio output.
Repeat (3) and (4) until no further improvement can be made.
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D. SYNTHESIZER 1|.F. TRACKING
Maintain connection of DVM but disconnect 10.7MHz tap at TP7.
Apply 98MHz (60dBu) to FM antenna input and tune to 98MHz.
Adjust C16 for OVDC +20mV reading on DVM.
Fine adjust L9 for minimum THD.
Repeat (3) and (4) until no further improvement can be made.
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E.
FRONT-END LF.
1.
Connect DVM between TP3 (level) and ground.
2.
Turn R48A fully clockwise and R48 fully counterclockwise.
3.
Apply 98MHz (12dBu) to antenna input.
4.
Carefully adjust FE5 to obtain minimum reading on DVM.
There should only be one minimum.
F.
R.F.
1.
Apply 98MHz (6dBu) to antenna input.
2.
Check if THD is better than 3%.
If not, proceed to (3).
3.
Adjust FE1, FE2, and FE3 by squeezing or stretching using a non-metallic tool until THD is better
than 3%.
4.
Check THD at 90OMHz and 106MHz with 7dBu input. If THD is more than 3% for both fre-
quencies, re-adjust until required THD is met.
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