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6-3-8
RIT ON/OFF
CONTROL
CIRCUIT
Q9 and Q17 make up the RIT ON/OFF
control circuit.
The voltage of the RIT
IC terminal
of J6 is fed to the
emitter of Q17 through R51. The terminal is 0 Volts when
the RIT is ON and 5 Volts when it is OFF.
Q17 prevents
the reverse flow from the base of Q9. The collector of Q9
is fed voltage from the RIT control and shunt to ground
when the RIT is OFF.
6-4
DRIVER
UNIT
6-4-1
FREQUENCY
DISPLAY
1C1-1C6 are the 7 segment LED indicators for the frequency
1MHz DIGITS DISPLAY
SCHEMATIC DIAGRAM
10MHz -
5V
5V
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1MHz DIGIT
display.
1IC3-IC6 are driven by IC22-IC25.
The input for
the drivers is taken from the BCD
output of 1C1, AO-D3
in the PLL.
IC1 and IC2 are driven by 1C16 and IC17.
The input of
each band is decoded
by !C14 and IC15 and D21-D35 to
indicate the MHz and 10MHz digits.
6-4-2
PHOTO-CHOPPER
CIRCUIT
D38 and D39 are infrared LED diodes and Q1 and Q2 are
the photo transistors.
D38 sends a continuous light source
to Q1 and D39 sends it to Q2. Between the diodes and the
transistors is a windowed chopper disk which is connected
directly to the shaft of the tuning knob.
The diodes and
photo transistors are set up so that the phase difference of
90 degrees results when the disc revolves.
The signal from
Qi and Q2 is fed to IC1 on the driver unit. Pin 3 of IC71 is
connected
to the data input pin (Pin 5) of flip-flop 1C3.
The output from Pin 4 is divided, and fed to Pins 5 and 6
of IC2.
One is fed directly and the other is fed through a
delay circuit.
[C2 is an exclusive OR gate IC, and both
pulses of the positive edge and the negative edge are added
to Pin 3 of IC3 and O output
is added
to IC3's reset
terminal
through the delay circuit so IC3 operates as a
monostable
multivibrator.
QO is fed to Pin 8 of IC2, the
1C17
03.5
O7
O14
iC14
is switched
ON
in
28MHz
band.
OA4
The segments "dp" and ''c"'
of 1MHz digit are turned on in any band.
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