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M-V7A/E
CIRCUIT DESCRIPTION
144MHz Band Transmit Circuit
@Outline
The transmitter directly oscillates the target frequency
and directly frequency modulation is applied with a variable-
capacity diode.
@Modulation circuit
In the control unit, the audio signals are amplified and
limited and passed through a splatter filter, then mixed with
subtones from the microprocessor, and directly frequency
modulated by a VCO (IC 10) with a variable-capacity diode.
@yYounger stage circuit
The signals from the PLL unit are input. to the drive
circuit.
Q56 and Q61 carry out stable amplification over a
broad
band
without
regulation
and can
obtain. adequate
output to drive the final module.
@APC circuit
The automatic transmission output control circuit (APC)
uses a differential amplfier circuit (1C16) to compare and
amplify the reference
voltage that forms the CPU
PWM
output and the DC voltage that detects part of the trans-
mission power with diodes (VHF:
D41 and D42; UHF:
D37
and D39) and for that output controls the DB voltage with a
preamp (Q67) and control transistor (Q66) and holds the
transmission output constant.
ANT
430MHz Band Transmit Circuit
@Outline
The transmitter directly oscillates. the target frequency
and directly frequency modulation is applied with a variable-
capacity diode.
@Modulation circuit
in the control unit, the audio signals are amplified and
limited and passed through a splatter filter, then mixed with
subtones from the microprocessor, and directly frequency
modulated by a VCO (iC 12) with a variable-capacity diode.
@Younger stage circuit
The signals from the PLL unit are input to the drive
circuit.
Q53, Q57, and Q60 carry out stable amplification
over a broad
band
without.
regulation
and can
obtain
adequate output to drive the final module.
Six sets of PWM data, high-, medium-, and low-power each
for VHF and UHF are stored into EEPROM memory (IC512)
and for each power condition, the data is extracted from the
EEPROM to control the power.
VHF
UHF
Final amp
LPF
LPF
Final amp
Ic3
>
~\
'
ma
<| Ica
DBA
\ FB
'
'
FB
DB
PWR
D41
PWR
D37
DET
D42
DET
|D39
IC512
;
E2PROM
Waveform
|
filter
Comparative amplitication
Circuit
1C16
6
Preamp
967
Control
|Q66
transistor
IC508
\
CPU
Reference
Fig.2 APC circuit
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