QUANTUN QP-750, Service Manual

Page: 12 / 79

QP-750 Service Manual
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2.3.2 Adjustment
Firstly reset the radio. Refer to All Reset Mode in ”Modes” for more details:
VCO adjustment
(1) Adjustment in user mode
(2)Setting Power supply voltage: 7.4V
Item Condition Measurement Adjustment Specification
Test
Instrument Terminal Parts Method
1.
2.Transmit
VCO lock
voltage 1. CH: TX high Digital
Voltmeter CV TC1350
TC1351
4.2V
±
0.3V
2. TX Low Check >0.7V
3.Receive
VCO lock
voltage 1. CH: RX high
4.2V
±
0.3V
2. RX low Check >0.7V
Transmitter adjustment
(1) Enter the manual adjust mode
(2) Setting Power supply voltage: 7.4V
Item Condition Test
Instrument
Method Purpose
Group 1 0. Transmit
frequency Turn to CH1;
Radio
Communicat
ion Test Set;
TX Test Adjust VR21 Frequency Error
≤
100Hz
1. TX power
Low Turn to CH1.
Adjust at 5 point (wideband).
Radio
Communicat
ion Test Set
TX TEST
HPF
：
20HZ
LPF
：
300HZ
PTT key
SFK2 key
1.1W±0.2W
2. CDCSS
balance Turn to CH2.
Adjust at 3 point (wideband), PTT key
SFK2 key
standard waveform
3. CDCSS
deviation Turn to CH3.
Adjust at 3 point (wideband),
1 point (medium band)
1 point (narrowband) PTT key
SFK2 key
750Hz (25KHz),
600Hz (20KHz)
400Hz (12.5KHz)
4. CTCSS
(67.0Hz)
deviation Low Turn to CH4.
Adjust at 3 point (wideband),
1 point (medium band)
1 point (narrowband). PTT key
SFK2 key
5. CTCSS
(136.5Hz)
deviation
Center Turn to CH5.
Adjust at 3 point (wideband),
1 point (medium band)
1 point (narrowband) PTT key
SFK2 key
6. CTCSS
(254.1Hz)
deviation High
Turn to CH6.
Adjust at 3 point (wideband),
1 point (medium band)
1 point (narrowband). PTT key
SFK2 key