Hytera MD78X, Service Manual

Page: 466 / 519

Tuning Description
VHF (136MHz
–
174MHz)
50
Items Method
than 14 dB
5. Set the output RF signal of HP8921 to -25 Bm/(current channel
fre22.425 MHz)
6. Adjust the vernier on Tuner until the “SINAD” value displayed on
HP8921 is less than 14 dB.
7. Press the Enter key on the keyboard to confirm your settings.
8. Click the “Save” button on Tuner to save the existing value to the
radio.
Front-end Gain
1.
Connect the radio to HP8921 via the antenna connector, and set
HP8921 to RX test mode.
2. Set HP8921 to output an unmodulated RF signal with a value of
“-70 dBm/Frequency (current channel frequency)”.
3. Press the Enter key on the keyboard to confirm your settings.
4. Click the “Save” button on Tuner to save the existing value to the
radio.
Receive Oscillator Voltage
1. Connect the radio to HP8921 via the antenna connector, and set
HP8921 to RX test mode.
2. Open the Tuner software and go to “TUNE_DATA -> RX ->
Receive Oscillator Voltage” in the left navigation tree.
3. Set HP8921 to output an unmodulated RF signal with a value of
“-47 dBm/Frequency (current channel frequency)”.
4. Click the “Save” button to save the existing value to the radio.
8.2.2
Testing the Radio
After tuning all the items of the radio, you need to test the digital RF signal of the mobile radio via
Aeroflex 3920 (Digital Radio Test set).
Transmitting
Step 1
Connect the mobile radio to Aeroflex 3920 via the antenna connector.
Step 2 Open the Tuner software and go to “TEST -> TX -> Transmit BER (0.153)”.
Step 3
Select the channel to be tested and select the corresponding power level (High Power or Low
Power) in “Parameter” on Tuner.
Step 4 Click the “Transmit On” button on Tuner.