Shure U4D - FM Detector Quadrature Coil Alignment (Channel A)

Shure U4D Dual Diversity UHF Receiver
23 25D1062 (AG)Service Procedures
FM Detector Quadrature Coil Alignment (Channel A)
AUDIO ANALYZER
RF SIGNAL GENERATOR
L310 for PCB 34A8507
P202
P202
P203
S201
ANTENNA A IN
P202P202
P203
S201
ANTENNA B IN
U305
DC BLOCK
TP306
NOTE: DC VOLTAGES ARE PRESENT
AT MOST RF TEST POINTS. USE A DC
BLOCK ON THE RF SIGNAL GENERATOR
TO PROTECT TEST EQUIPMENT.
(OFF) (OFF)
J302
FL311 for PCB 34A8703
Figure 7. FM Detector Quadrature Coil Alignment Connections
1. Set the rf signal generator Frequency to Fo. Set the Level to
–86 dBm and verify the Deviation as follows:
UA, UB,MA, MB, MC, MD: 45 kHz deviation at 1 kHz modulation
KK: 40 kHz deviation at 1 kHz modulation
II: 28 kHz deviation at 1 kHz modulation
2. Connect the rf signal generator to the ANTENNA A input.
3. Connect the audio analyzer to U305, pin 7 (TP306).
4. Make sure that audio analyzer 400 Hz high-pass filter and
the 30 kHz low-pass filter are activated.
5. For PCB version 34A8507 tune L310 for maximum audio output
at TP306. For PCB version 34A8703 tune FL311 for maximum
audio output at TP306. The low limit is 250 mVrms. There is no
high limit.