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Shure U4D Dual Diversity UHF Receiver
25
25D1062 (AG)
Service Procedures
THD Verification and RSSI Adjustment (Channel A)
TP306 AUDIO CH A
TP328 RSSI CH A
R355
P202
P202
P203
S201
ANTENNA A IN
P202
P202
P203
S201
ANTENNA B IN
RF SIGNAL GENERATOR
AUDIO ANALYZER
DC VOLTMETER
NOTE: DC VOLTAGES ARE PRESENT
AT MOST RF TEST POINTS. USE A DC
BLOCK ON THE RF SIGNAL GENERATOR
TO PROTECT TEST EQUIPMENT.
DC BLOCK
(OFF)
(OFF)
J302
L310 for PCB 34A8507
L311 for PCB 34A8703
Figure 9.
Channel A RSSI Alignment
1. Change the rf signal generator Level to –50 dBm.
2. Measure the total harmonic distortion (THD) at TP306
(U305 pin 7). It should be less than 0.5%. If not adjust L310 for
PCB version 34A8507 or adjust FL311 for PCB version 34A8703
to minimize the distortion.
3. Adjust R355 for Vrssi at the wiper (TP328). The Vrssi should be
2.75
±
0.1 Vdc for 34A8507F and earlier PCB versions.The Vrssi
should be 2.3
±
0.1 Vdc for 34A8507G and later versions of the
board and the 34A8703 PCB version.
Summary of Contents for U4D
Page 11: ...Shure U4D Dual Diversity UHF Receiver 10 25D1062 AG Preliminary Tests Audio Rf Board Side 2...
Page 46: ...Shure U4 UHF Diversity Receiver 25D1062 TL 45 U4 Rf Audio Printed Circuit Board Legend Side 1...
Page 47: ...Shure U4 Diversity UHF Receiver 46 25D1062 TL U4 Rf Audio Printed Circuit Board Legend Side 2...