Adjustment Of Pll Frequency; Adjustment Of Receiver Front-End; Adjustment And Confirmation Of Deviation - Standard Horizon Quest GX1255S Service Manual

— Confirmation —
r Use the [ H/L ] key to set transceiver to high power
and set the channel to EXP01. With the PTT switch
pressed, confirm that RF power is between 23 W and
27 W.
r Use the [ H/L ] key to set transceiver to low power. With
the PTT switch pressed, confirm that RF power is
between 0.5 W and 1.0 W.
r As descried above, confirm RF power at EXP04 and
EXP05. Set transceiver to high power and confirm
that RF power is between 23 W and 27 W. Set trans-
ceiver to low power and confirm that RF power is
between 0.5 W and 1.0 W.

Adjustment of PLL Frequency

Adjust the frequency in the transmit mode and local fre-
quency in the receive mode.
— Adjustment —
r Setup the test equipment as shown below.
Sampling
Coupler
50-ohm
Dummy Load
ANT
Deviation
Meter
r Set the channel to CH16. With the PTT switch pressed,
adjust TC1001 so that RF frequency is 156.80000
MHz ± 50 Hz.

Adjustment and Confirmation of Deviation

Adjust deviation in the transmit mode.
— Adjustment —
r Setup the test equipment as shown below.
r Set the channel to CH16.
r Set the output of the audio generator (AG) to 1 kHz
and 150 mV.
r With the PTT switch pressed, adjust VR1003 so that
the maximum deviation is ±4.5 kHz.
r Decrease the output level of AG by 20 dB (the output
level of AG should be 1/10).
r With the PTT switch pressed, adjust the output level
of AG so that the deviation is ±3.0 kHz.
r Increase the output level of AG by 20 dB (10 times of
the output level of AG) which is supposed to be De-
tective Modulation Level ±4.5 kHz).
r Repeat steps 3 though 6 three times so that deviation
is ±3.0 kHz and the maximum deviation is ±4.4 kHz
to ±4.6 kHz.
AF Signal
GX1255S
Generator
J1003
Pin 1
— Confirmation —
r Set the output of the AG to 1 kHz and 150 mV.
r Set the channel to EXP01, confirm that maximum
deviation is between ±4.3 kHz and ±5.0 kHz.
r Set the channel to EXP02, confirm that maximum
deviation is between ±4.3 kHz and ±5.0 kHz.
r Set the channel to EXP04, confirm that maximum
deviation is between ±4.0 kHz and ±5.0 kHz.
r Set the channel to EXP05, confirm that maximum de-
viation is between ±4.0 kHz and ±5.0 kHz.

Adjustment of Receiver Front-end

Adjust the receiver front-end coil.
— Adjustment —
r Setup the test equipment as shown below.
Tracking
Generator
ANT
r Set the center frequency of t he spectrum analyzer to
159.00 MHz, set SPAN to 20.00 MHz, set RBW and
VBW to 30 kHz, and set SWP to 56 ms.
r Adjust T1001, T1002, T1003, T1004, and T1005
until the wave form shown in below is obtained.
ATTEN 20dB
RL 10.0dBm
CENTER 159.00 MHz
*RBW 30 kHz VBW 30 kHz
Note: Adjust the output of the tracking generator so that
RF AMP and spectrum analyzer will not saturate.
Figure shows the reference wave form. The wave form
varies with measuring instruments. It is impotent to take
the lowest possible value at the stop band near 150 MHz
and the highest possible value at the band near 156 MHz.
Each coil shall be adjusted at the range between the initial
condition and right and left revolving.
Alignment
Spectrum
GX1255S
Analizer
TP1013
GX1255S-FRONT-END
10dB/
SPAN 20.00 MHz
SWP 56.0 ms
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