Service manual

ALIGNMENT AND TEST PROCEDURES
7-7
Month 2000
Part No. 001-2004-601
assembly). Replacement of components within the
power control circuitry of the RF Interface Board are
unlikely to affect the calibration of the power control.
NOTE: Replacement of Q501, Q502, Q503 or U501
does
not require the adjustments in this Section.
7.3.2 DRIVER TUNING AND LIMIT ADJUST-
MENTS
1. Connect an antenna or dummy load to the RF port
(50 ohm impedance).
2. Connect the:
Power supply ground lead to P105
+15V DC lead to P103
+26.5V DC lead to P101
36-pin cable to J101 on the RFIB
3. Set the signal generator to +19 dBm ±0.1 dB.
Connect the signal generator to A9.
4. Use the "Turn on carrier" button to key the PA.
5. Monitor the voltage on R45 on the RFIBand set R76
for 1.3V DC (see Figure
7-5).
7.3.3 POWER AMPLIFIER TUNING
This procedure assumes that either:
• The carrier is chosen and the coaxial cable from the
exciter is putting out +19 dBm
OR
• A test signal is being injected to the PA with +19
dBm.
Connect an antenna or dummy load to the RF port
(50 ohm impedance).
400-430 MHz use 415 MHz 110W
430-470 MHz use 460 MHz 110W
470-512 MHz use 490 MHz 100W
1. Set R510, R521 and R530 on the PA board full
clockwise before applying power to the PA (or PA
deck and RFIB assembly), see Figure
7.3.
2. Set Forward Power Adjust R611 and Reflected
Power Adjust R661 on the power detector board
fully counterclockwise (see Figure
7.3).
3. Monitor the voltage on R45 on the RFIBand set R76
for 1.3V DC (see Figure
7-5). This sets the current
limit point for driver Q501 at hot temperatures.
4. Set each of the quiescent currents for Q501, Q502
and Q503 for 100 mA (DC) each.
5. Program the power output as follows:
400-430 MHz 110W
430-470 MHz 110W
470-512 MHz 100W
6. Use the "Turn on carrier" button to key the PA. Out-
put power will be approximetly 80W.
7. Monitor the voltage on U501, pin 2 (power control
voltage) and tune C600 for minimum voltage (see
Figure
7.3).
8. Set Forward Power Adjust R611 for rated power
(110W or 100W).
9. Use the "Turn on carrier" button to unkey the PA.
10.Disconnect the antenna or dummy load from the RF
port.
11.Use the "Turn on carrier" button to key the PA.
NOTE: This will not harm the PA.
12.Adjust Reverse Power Calibration Pot R661 for
equal voltages on W121 and W126 on the RFIB or
for equal Forward and Reverse Power (see Figure
7-5).
13.Use the "Turn on carrier" button to unkey the PA.
Figure 7-3 POWER EXTENDER CABLES
RED
WHITE
BLACK
WHITE
BLACK
GREEN
WHITE
BLACK
GREEN
RED
WHITE
BLACK
(INCLUDED IN 2000 SERIES SERVICE KIT 250-2000-230)