Service manual

ALIGNMENT AND TEST PROCEDURES
7-14
Month 2000
Part No. 001-2004-601
2. On the MAC, plug a Speaker/Microphone into
J101/J102.
3. Adjust R236 until the 1 kHz tone is heard.
Receiver Desense Check
1. Adjust the RF generator for 100 µV into the receiver
with a 1 kHz tone at ±3 kHz deviation
(25 kHz channels) or ±1.5 kHz (12.5 kHz channels).
2. On the MAC, connect a 16 ohm load and distortion
analyzer to J101 or J104.
3. Adjust R236 for 2.8V RMS.
4. Re-adjust the RF generator output for 12 dB
SINAD.
5. Use the "Turn on carrier" button to key the
transmitter.
6. SINAD should not degrade more than 1 dB or to no
less than 11 dB SINAD.
7. Use the "Turn on carrier" button to unkey the
transmitter.
Receiver Miscellaneous Tests (Optional)
Several additional tests may be performed on the
Repeater Receiver as listed below:
• Signal Displacement Bandwidth
• Adjacent Channel Rejection
• Offset Channel Selectivity
• Intermodulation Rejection
• Spurious Rejection
• Audio Response
• Audio Sensitivity
Perform the Test desired using the appropriate RF
Generators, modulation frequencies and levels,
RS-232 levels and test probes following the latest TIA
document measurement procedures.
7.4.5 RECEIVER RSSI ADJUSTMENT
NOTE: Use this procedure only when an audio ana-
lyzer is available.
1. Adjust the RF generator for 0.29 µV into the
receiver with a modulation tone of 1 kHz at
±3 kHz deviation.
2. In the Receiver, adjust R261 for 0.8V DC (±0.02V)
at TP3.
7.4.6 TRANSMIT AUDIO/DATA LEVEL ADJUST-
MENTS
NOTE: All audio generators and audio voltmeters are
unbalanced unless specifically stated otherwise.
Audio Deviation Limit Adjustment
1. On the MAC, apply a 1 kHz tone at -3 dBm
(548 mV RMS) to P100, pin 32.
2. Insert test cables into J100/J103 and connect to an
AC voltmeter.
3. Use the "Turn on carrier" button to key the
transmitter.
4. Adjust R305 for 0 dBm (775 mV RMS).
5. Use the "Turn on carrier" button to unkey the
transmitter.
6. On the MAC, apply a 1 kHz tone at +7 dBm
(1.73V RMS) to P100, pin 32. (Set modulation
analyzer LPF to 3 kHz.)
7. Use the "Turn on carrier" button to key the
transmitter.
8. Adjust U149 with the Level Control buttons to set
the maximum allowed deviation at ±3.5 kHz devia
-
tion (25 kHz channels) or
±1.6 kHz (12.5 kHz channels).
9. Use the "Turn on carrier" button to unkey the
transmitter.
10.Remove the signal from P100, pin 32.