Specifications

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7.1. RECEIVER
RX VCO
RX VCO is pre-tuned at the factory and adjustment should not be required
To identify existence of defect of RX VCO, check the VCO Control voltage.
1. Set the unit to the highest receive frequency, 490MHz(UHF2), 174MHz(VHF) and verify
the VCO control voltage is under 10.0 Volts. If it’s over 10.0 Volts, adjust C308 of RX
VCO to 10.0 Volts
2. Set the unit to the lowest receive frequency 450MHz(UHF2), 148(VHF) and verify that
the VCO voltage is above 2.0 Volts. Adjust C308 to 2.0 Volts.
※ Note: Use TP1 to measure the voltage.
AUDIO OUTPUT LEVEL Adjustment
1. Select a receiver channel that is programmed for Standard band (25kHz) operation.
2. Prepare standard test signal as follows.
a. Set the RF signal generator to the receiver frequency.
b. And then set the AF modulation signal to 1 kHz at 3kH deviation.
c. Adjust the RF output level of the RF signal generator to –47dBm.
3. Apply a standard test signal to the receiver antenna terminals.
4. Adjust RV401 for the specific audio output level.
LEVEL SHIFTER for Modem option Board (ACC-513, ACC-514)
1. Select a receiver channel which is programmed for Standard band (25kHz) operation.
2. After Preparing standard test signal for Standard band, apply that signal to the antenna
terminals of receiver.
3. Adjust RV403 until the center voltage of demodulated signal (1KHz sine wave) of TP401 is
2.5 Volts.
4. Select a receiver channel which is programmed for Narrow band (12.5kHz) operation.
5. After Preparing standard test signal for Narrow band (only decrease deviation of AF
modulation signal as 1.5K from standard test signal for Standard band), apply that signal to
the antenna terminals of receiver.
6. Verify the center voltage of demodulated signal of TP401 is 2.5 Volts. If different, Adjust
RV403 until the center voltage is near 2.5 Volts for each band (25KHz / 12.5KHz).