Handset Section; Tel 13942296513 - Sony SPP-SS955 Service Manual

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6-2. HANDSET SECTION

• Make the set in Test mode (see page 16)
1. Checking RX I&Q Output Level
Setting:
oscilloscope
level meter
+ +
– –
SSG
Procedure:
1. Place the handset in the Continuous Receive mode (CH1, LNA,
AGC ON).
2. Set the SSG frequency to the frequency on CH1 + 300 kHz,
and the RF output level to –95 dBm.
3. Measure the output level of RXIN, RXIP, RXQN, and RXQP
with a level meter. At this time, confirm with an oscilloscope
that a sine wave of 300 kHz is output.
4. Confirm that the measured output level is –26.0 to 19.0 (TYPI-
CAL –22.0) dBV. If IC502 was replaced (there is no ID data),
the output level is –31.0 to –24.0 dBV.
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5. Also, execute steps 1 through 4 for the channels 10 and 20.
* For the frequency on each channel, see page 12.
2. Checking TX Center Frequency
Setting:
• short: TP555 ↔ TP553
frequency counter
+
–
Procedure:
1. Short TP555 and TP553 (GND) on the HAND MAIN board in
the handset.
2. Place the handset in the Continuous Transmit mode (CH1, High
power).
3. Measure the ANT OUT frequency of the RF module in the hand-
set using a frequency counter.
4. Confirm that the measured frequency is 903.600 MHz ±
27 kHz.
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TP520: RXIP
TP521: RXIN
TP522: RXQP
TP523: RXQN
TP553: GND
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3. Checking TX output
Setting:
peak power meter
+
–
Procedure:
1. Place the handset in the Continuous Transmit mode (CH1, High
power).
2. Measure the ANT OUT output of the RF module in the hand-
set using a peak power meter.
3. Confirm that the measured output is 80 mW (MIN 20 mW).
4. Also, execute steps 1 through 3 for the channels 10 and 20.
CH10: 80 mW (MIN 20 mW)
CH20: 50 mW (MIN 10 mW)
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