Hytera MD78X, Service Manual

Page: 465 / 519

VHF (136MHz
–
174MHz)
Tuning Description
49
Items Method
Filter1: <20 Hz HPF
Filter2: <15 kHz LPF
De-Emphasis: off
3. Open the Tuner software and go to “TUNE_DATA -> TX ->
Modulation Balance” in the left navigation tree. Then select an
appropriate channel.
4. Click the “Transmit On” button on Tuner. Then set the modulation
signal of HP8921 to “100 Hz”.
5. Adjust the value in the dialog box on Tuner until the frequency
deviation displayed on HP8921 is “5 kHz”.
6. Press the Enter key on the keyboard to confirm your settings.
7. Click the “Save” button on Tuner to save the existing value to the
radio.
8. Click the “Transmit Off” button on Tuner.
Transmit Oscillator Voltage
1. Connect the radio to HP8921 via the antenna connector, and set
HP8921 to TX test mode.
2. Open the Tuner software and go to “TUNE_DATA -> TX ->
Transmit Oscillator Voltage” in the left navigation tree.
3. Click the “Save” button to save the existing value to the radio.
RX Section
Front-end Filter
1. Connect the radio to HP8921 via the antenna connector.
2. Connect the Audio Out port of the radio to the Audio In port of
HP8921, and set HP8921 to RX test mode.
3. Set the HP8921 parameters as follows:
Output RF signal: -118 dBm/Frequency (current channel
frequency)
Modulation frequency: 1 kHz
Modulation deviation: 3 kHz
4. Open the Tuner software and go to “TUNE_DATA -> RX ->
Front-end Filter” in the left navigation tree. Adjust the vernier on
Tuner until the “SINAD” value displayed on HP8921 is greater