Shure T1 Body-Pack Transmitters
15
Service Procedures
25C1016 (CC)
F: Deviation Reference Voltage
1. Turn off the transmitter.
2. Set the
RF signal generator as follows:
(a) Enter the carrier frequency.
(b) Select FM modulation and enter the following:
Modulation Source: Int 1 kHz
FM Deviation: ±15 kHz
Amplitude: –38 dBm
3. Select a receiver for the T1, making sure it is set to the same
frequency as the transmitter. Disconnect the receiver’s antenna
(non-diversity) or antennas (diversity).
4. Solder the 50 Ω cable to the receiver’s antenna pads:
T3: Center conductor to
TP1, and shield to TP2
T4: Center conductor to
TPA1, and shield to TPA2
5. Connect the
BNC end of this cable to the output of the RF signal
generator.
6. Set the Volume control on the front panel of the receiver to its
maximum position (fully clockwise). Then turn on the receiver
and set its Squelch control to the midpoint position.
7. Measure the rms voltage developed across the unbalanced out-
put of the receiver. You should find approximately 775 mVac.
This is the audio output voltage that corresponds to a deviation
level of 15 kHz.
Record this voltage as the deviation reference voltage.
Note: At this point you may want to press the audio analyzer’s
Log/Lin button (to measure in dBm) and activate the Ratio button
to perform the relative measurement in the next subsection.
G: Deviation Adjustment
1. Turn off the RF switch on the RF signal generator.
2. Remove the test cable from the receiver and reconnect the an-
tenna(s) to the receiver board.
3. Turn on the T1 and set its Mute switch to “On.”
4. Reconnect the output of the audio analyzer to the input of the
T1.
5. Reset the frequency of the audio analyzer to 1 kHz. Make sure
that 775 mV is still present at
TP3.
6. Measure the voltage at the unbalanced output of the receiver.
Adjust R217 for 0 dB (±1 dB) relative to the deviation reference
voltage measured in step 7 of the preceding subsection.
