Shure U1/U1L Body-Pack UHF Transmitter
25C1021 (BG)18
Service Procedures
Tone Key Level Adjustment
AUDIO ANALYZER
U1 Transmitter Audio Analyzer
Power: +2.5 Vdc Measurement: AC level
Gain: Minimum; for JB models,
set to MAX
Output: None
Filters:
Low-Pass (30 kHz): OFF
High-Pass (400 Hz): OFF
Figure 9. Tone Key Level Adjustment Test Set-Up
1. Use a dc power supply to apply 2.5 ± 0.01 V to the battery
terminals, with no audio applied to the audio input.
2. Make sure no filters are used on the measuring instrument.
3. The tone key frequency will be approximately 32.768 kHz.
Adjust R224 so that the tone key level of –22.8 ± 0.1 dBu
(56 mV) is measured at U202, pin 1. For JB models, this level
should be –24.7 dBu ± 0.1 dBu (45 mV).
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