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SECTION 4
ELECTRICAL ADJUSTMENTS
Setting :
trackig generator
(GND)
spectrum analyzer
(GND)
FM RF signal
generator
generator
(GND)
digital
voltmeter
(GND)
RF BOARD (SINGLE) ADJUSTMENT
1. 2nd local oscillator Adjustment
Procedure :
(1) Connect a tracking generator to TP10 and a spectrum ana-
lyzer to TP6.
(TG level = – 40 to – 50dBm, spectrum analyzer span =
200MHz)
(TG level = – 40 to – 50dBm, spectrum analyzer span =
200MHz)
(2) Receive a 600MHz signal.
(3) Repeatedly adjust CT303, 304 and 305 for an optimal wave-
(3) Repeatedly adjust CT303, 304 and 305 for an optimal wave-
form at center frequency of 277.5MHz.
(4) Receive the 25MHz signal.
(5) Adjust the 2nd local oscillator to 555MHz with CT302.
(5) Adjust the 2nd local oscillator to 555MHz with CT302.
(spectrum analyzer span = 10kHz)
2. 1st local oscillator Adjustment
Procedure :
(1) Connect a spectrum analyzer to TP5.
(2) Receive a 767.5MHz signal.
(3) Adjust the CT301 so that 1st local oscillator = 1000MHz
(2) Receive a 767.5MHz signal.
(3) Adjust the CT301 so that 1st local oscillator = 1000MHz
(spectrum analyzer span = 10kHz)
3. 1st IF (low) Adjustment
Procedure :
(1) Connect a tracking generator to TP5 and a spectrum analyzer
to TP7.
(2) Recive a 500MHz signal.
(3) Repeatedly adjust CT201, 202 and 203 for an optimal wave-
(3) Repeatedly adjust CT201, 202 and 203 for an optimal wave-
form (ladder shape) at center frequency of 232.5MHz.
(TG level = – 30 to – 40dBm, spectrum analyzer span =
200MHz)
(TG level = – 30 to – 40dBm, spectrum analyzer span =
200MHz)
Adjustment Location :
RF board (see page 14)
IF BOARD (SINGLE) ADJUSTMENT
1. 3rd local oscillator Adjustment
Procedure :
(1) Connect a spectrum analyzer to TP2.
(2) Receive a 49.975MHz signal.
(3) Adjust the CT401 so that the 3rd local oscillator =
(2) Receive a 49.975MHz signal.
(3) Adjust the CT401 so that the 3rd local oscillator =
44.5500MHz. (spectrum analyzer span = 10kHz)
(4) Recive a 50.0125MHz signal.
(5) Adjust the 3rd local oscillator to 44.5425MHz with RV401.
(5) Adjust the 3rd local oscillator to 44.5425MHz with RV401.
(spectrum analyzer span = 10kHz)
Adjustment Location :
IF board (see page 14)
RF & IF BOARD (COMBINATION) ADJUSTMENT
1. 2nd IF (narrow) Adjustment
Procedure :
(1) Connect a tracking generator to RF (RF board) TP6 and con-
nect a spectrum analyzer to IF (IF board) TP1 by way of a
0.5pF capacitor.
0.5pF capacitor.
(2) Receive a 29MHz signal.
(3) Align for an optimal waveform with T206.
(3) Align for an optimal waveform with T206.
(ladder waveform with minimum ripple)
(TG level = – 50dBm, spectrum analyzer Center freq. =
45MHz, span = 100kHz)
(TG level = – 50dBm, spectrum analyzer Center freq. =
45MHz, span = 100kHz)
2. 2nd IF (wide) Adjustment
Procedure :
(1) Connect a tracking generator to RF (RF board) TP6 and con-
nect a spectrum analyzer to IF (IF board) TP3.
(2) Receive a 70MHz signal.
(3) Adjust so the 45MHz is at maximum by using CT402 and
(3) Adjust so the 45MHz is at maximum by using CT402 and
T205.
(TG level = – 50dBm, spectrum analyzer Center freq. =
45MHz, span = 50MHz)
(TG level = – 50dBm, spectrum analyzer Center freq. =
45MHz, span = 50MHz)
3. AGC Adjustment
Procedure :
(1) Connect a FM RF signal generator to the BNC (ANT IN)
connector.
(2) Connect a digital voltmeter to RV403 center tap (COMMON).
(IF board)
(3) Receive a 122MHz signal (input level 80d
µ
EMF, AM, modu-
lation 30%).
(4) Adjust RV403 so that digital voltmeter reading is at 1.68
±
0.02V.
Adjustment Location :
RF, IF board (see page 14)
* Use semirigid cable when connecting the tracking generator and
spectrum analyzer to the circuit board.
* Spectrum analyzer settings shown in the ( ) are reference values.
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