Shure U1 Service Manual page 16

Shure U1/U1L Body-Pack UHF Transmitter
Rf Alignment
Service Procedures
J3
U1 Transmitter
Power (S103): ON
Gain (R201): For JB models:
set to maximum
Figure 5. Alignment Test Set–Up
Rf Alignment Set-Up
1. Proper adaptors should be used to connect the test equipment.
2. Use RG58 or other low-loss 50 Ω cables for all rf connections.
3. Include the insertion loss of the cables and connectors in
rf conductive power measurements.
4. Connect the rf–audio board to the digital board through
board interconnects J104 and J200.
5. On all models except JB, audio GAIN potentiometer R201 does
not need to be preset to any position. On JB models, R201
GAIN should be set to maximum.
6. All rf measurements should be made from the antenna output
connection, the 50Ω SMC connector on PCB versions "G" and
earlier or through the P1824 test cable on PCB versions "H" and
later. For JB models with SMT rf test connector, use PT1838–AF
with PT1838–AJ.
Rf Alignment
1. Slide the ON/OFF switch (S103) to the ON position.
2. Connect the transmitter to the frequency counter via J3.
3. Determine the transmitter operating frequency by comparing the
Group and Channel information on the LCD to the tables in the
User Guide and User's Guide Supplements.
4. Adjust variable capacitor C239 until the frequency counter mea-
surement matches the desired operating frequency, ±1 kHz.
14
FREQUENCY COUNTER
Frequency Counter
Connect CH2: J3
25C1021 (BG)
CH 2
CH 1