Standard Communications mt930b, Service Manual

Page: 58 / 155

Maintenance
Page 6-26 Service Manual MT930B
CHECKS AND ADJUSTMENTS
RF Module AGC Properties Adjustment
Adjustment Procedure:
1. Adjust R109 so the voltage at TP01 is 2.2 V.
2. At this time, verify that the voltage at R108 is 5 V.
RF MODULE CHECKS AND ADJUSTMENTS
RF Module Frequency Response Check
Check Conditions:
•
Input: J101, J102, J103, or J104 (75 Ω )
•
Output: J105 (50 Ω ); –35 dBm
• AFC switch: OFF
• AGC switch: OFF
• MGC: At a position corresponding to –35 dBm at J105
Check Procedure:
1. After correcting the scalar network analyzer, connect as shown in Figure 6-9.
10294
Figure 6-6. Equipment Setup for RF Module Frequency Response Check
2. Set the receive frequency to 1210 MHz.
3. Adjust the MGC so the level at J105 is –35 dBm.
4. Verify that the deviation inside the ± 10 MHz bandwidth for which the
1210 MHz level is used as a reference is 0.5 dB or less. If it is more than
–35 dB, check whether CA01 in the tuner pack is out of alignment.
Note: There is no change in the slope of the bandwidth even if F101 is
adjusted. Refer to Figure 6-10 for the locations that change when
F101 is adjusted.