Audio Alignment - Shure U1 Service Manual

Shure U1/U1L Body-Pack UHF Transmitter

Audio Alignment

Deviation Reference Voltage
S201
TONE-KEY
SWITCH
RF SIGNAL GENERATOR
U4 Receiver
Output: Unbalanced
Gain: Maximum
Squelch: Mid
Tone Key (S201): OFF
Figure 7. Deviation Reference Voltage Test Set-Up, Using a U4 Receiver
Service Procedures
U4 RECEIVER
DC BLOCK
Audio Analyzer
Measurement: AC level
Filters:
Low-Pass (30 kHz): ON
High-Pass (400 Hz): ON
1. The U1 transmitter should be turned OFF for this procedure.
2. Connect the rf signal generator to antenna A or B on a U4
receiver. Make sure the dc block is on the rf signal generator.
3. Set the rf signal generator to the same frequency as the
U1 transmitter.
4. Set rf signal generator modulation to 1 kHz and set the deviation
to 45 kHz for UA, UB, MA, MB, MC, and MD models, 40 kHz for
KK models, and 5 kHz for II models.
5. Set the output amplitude of the rf signal generator to –50 dBm.
6. Turn the U4 receiver ON and set the tone key switch (S201)
inside the U4 receiver to the OFF position. This will disable the
receiver tone key function.
7. Connect the audio analyzer to the unbalanced output of the U4
receiver. The voltage should be 4.2 ± 0.5 dBu (1.26 ± 0.07 V) for
UA, MA, MB, MC, MD, and KK models, and –26.2 ± 0.5 dBu for
II models.
Note the voltage obtained; it is the deviation reference voltage.
8. Disconnect the rf signal generator from the U4 receiver and
return the tone key switch (S201) to the ON position.
16
NOTE: DC VOLTAGES ARE PRESENT
AT MOST RF TEST POINTS. USE A
DC BLOCK ON THE RF SIGNAL
GENERATOR TO PROTECT
TEST EQUIPMENT.
AUDIO ANALYZER
Rf Signal Generator
INT: FM
INT: 1 kHz
Output Amplitude:
25C1021 (BG)
–50 dBm