Motorola PM1200, Basic Service Manual

Page: 45 / 138

6880309U09-A October 26, 2007
Radio Alignment and Programming Procedures : Alignment 5-3
Because of the bridge audio amplifier circuit used in the radio, it is necessary to construct and use a
simple audio load test adapter as shown in the schematic diagram above, when conducting receiver
alignment steps.
Figure 5-1. AF Test Adapter Schematics
5.4 Alignment
5.4.1 PLL & Transmitter
• Set up the test equipment as shown on Figure 5-2 on page 5-5 for transmitter alignment.
• Maintain the supply voltage at 13.4 V DC for all steps.
5.4.2 PLL VCV
1. Connect the positive lead of the DC voltmeter to the test point TP1010 (VCV) on the Main
Unit, and the negative lead to chassis ground.
2. Set the transceiver to the high band edge frequency channel, then adjust trimmer-capacitor
T1005 on the Unit for 7.0 V on the voltmeter.
3. Key the transmitter, and adjust trimmer-capacitor T1006 on the Unit for 7.0 V on the
voltmeter.
4. Next select to the low edge frequency channel and confirm about 1.8 V (1.5 V to 2.1 V) on the
voltmeter.
5. Key the transmitter, and confirm about 1.8 V (1.5 V to 2.1 V) on the voltmeter.
Table 5-1. Alignment Channel Frequencies
Channel
Frequency (MHz)
(Simplex)
CTCSS
Encode
DCS
Encode
CH1 29.71/ 37.01 None None
CH2 33.35/ 43.01 None None
CH3 36.99/ 49.99 None None
CH4 33.35/ 43.01 151.4 Hz None
CH5 33.35/ 43.01 None 023
To 20-pin
accesories
connector
2Ω
10W
GND
Attenuated
Test Output
To the input of the
audio analyzer
2Ω
10W
(4Ω Dummy Load)