Alinco DJ-V57, Руководство по обслуживанию

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5. Squelch
The AF signal from pin 9 of IC105 is input to pin 8 of IC105. The input signal
is output from pin 14 of IC105 passing through the noise filter amplifier and
rectifier circuits inside of IC105. The rectified signal is input to the A/D port
pin 82 of microcomputer IC109. Judging the signal, the microcomputer controls
ON/OFF of the audio output.
6. Audio
The AF signal from pin 9 of IC105 is amplified at Q119, and then it is input to
pin 6 of IC106 passing through the active high pass filter Q118. The volume of
audio signal is adjusted at the D/A converter IC106. The audio signal is input
to pin 2 of audio power amplifier IC104 and output from pin 6 to drive a
speaker.
7. VCO
[VHF]
VCO in VHF band consists of the Colpitts oscillator. D106, D112, L112 and
L115 determine the oscillating frequency, and the signal is oscillated at the
transistor Q103. L115 is passed at shift transistor Q107 when transmitting.
The oscillated signal is supplied to pin 16 of PLL-IC102 passing through the
buffer amplifier Q114.
[UHF]
VCO in VHF band consists of the Colpitts oscillator. D119, D124, L127 and
L129 determine the oscillating frequency, and the signal is oscillated at the
transistor Q108. L129 is passed at shift transistor Q111 when transmitting.
The oscillated signal is supplied to pin 16 of PLL-IC102 passing through the
buffer amplifier Q114.
8. PLL
PLL-IC102 is used to control the oscillating frequency of VCO. IC102 is
controlled by the serial control signal sent from the microcomputer IC109. The
12.8MHz for reference frequency of IC102 oscillates in the TCXO X101.
IC102 compares the frequency gained by dividing the signal input to pin 16 of
IC102 by the control signal from IC109 with the frequency gained by dividing
the reference frequency of 12.8 MHz. When the phase difference is found as a