Alinco DJ-G5, Руководство по обслуживанию

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3) PLL Synthesizer Circuit
1 PLL
The data is sent to the PLL IC (IC53) Pin2 and the clock is sent to Pin3 from CPU
(IC508), then the ratio of the division is decided each in L band and R band.
Each VCO oscillating signal is amplified in the buffer (Q73: L band, Q66: R band),
and the signal in L band is applied to Pin15, then the signal in R band is applied to
Pin6. The programmable divider of IC53 is determined by frequency data, and it
divides (1/N) input signal of IC53. Resulting signal will be 5kHz or 6.25kHz.
2 Reference frequency division
The reference frequency of 5kHz or 6.25kHz according to the channel step is
produced by dividing the reference oscillation 12.8MHz (X51) by 2560 or 2048, the
data from CPU (IC508). The channel steps of 5kHz, 10kHz, 15kHz, 20kHz,
25kHz, 30kHz and 50kHz use the reference frequency of 5kHz, and the channel
step of l2.5kHz uses the reference frequency of 6.25kHz.
3 Phase comparator
The reference frequency of IC53 is 5kHz or 6.25kHz.
The VCO output frequency divided by N is compared with 5kHz or 6.25kHz in the
phase comparator.
4 PLL Loop Filter Circuit
If the phase error should occur in PLL, the charge pump of IC53 Pin13 (L band)
and Pin8 (R band) outputs the pulse. The signal is converted into the DC voltage
in PLL loop filter, then inputted to the varicap of each VCO unit.
5 VVCO Circuit (VHF Band)
Q705 is turned ON, and the desired frequency is oscillated in the Colpitts osclllator
consisting of Q701. The frequency control voltage is apprled to the varicap (D702,
D703), and the osciflating frequency is changed, then amplified in VCO buffer
(Q703), and outputted from the VCO unit.
6 VVCO Circuit (UHF Band)
Q704 is turned ON, and the desired frequency is oscillated in the Colpitts oscillator
consisting of Q702. The frequency control voltage is applied to the varicap (D704,
D705), and the oscillating frequency is changed, then amplified in VCO buffer
(Q703), and outputted from the VCO unit.
7 UVCO Circuit (UHF Band)
Q605 is turned ON, and the desired frequency is oscillated in the Colpitts oscillator
consisting of Q601. The frequency control voltage is applied to the varicap (D602,
D603), and the oscillating frequency is changed, then amplified in VCO buffer
(Q603), and outputted from the VCO unit.
8 UVCO Circuit (VHF Band)
Q604 is turned ON, and the desired frequency is oscillated in the Colpitts oscillator
consisting of Q602. The frequency control voltage is applied to the varicap (D604,
D605), and the oscillating frequency is changed, then amplified in VCO buffer
(Q603), and outputted from the VCO unit.
4) CPU and Peripheral Circuit
1 LCD Display Circuit
The strobe, serial data, and clock are sent to the LCD driver (IC503) Pin 75~77
from CPU (IC508), and the LCD is activated with 1/4 duty and l/3 bias. The frame
frequency is 137Hz.
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