3-
4-
2 LED
INDICATOR
CIRCUIT
This LED
is
lit
in the transmit mode,
but
when the power supply voltage becomes
less
than 7V,
it
will
not
be
lit.
The power supply voltage
is
divided
by
R148 and R149, and applied
to
the
base
of
0121.
The emitter
of
0121
is
connected
to
the regulated
6V
source.
When
the power supply voltage
is
more than 7V,
0121
is
turned OFF,
0122
is
turned ON and
T+6V
is
applied
to
the LED through
0122
and R150, and
the LED
is
lit.
3-
4-
3 DIODE
MATRIX
BOARD
The
set
incorporates a diode
matrix
board
to
determine its operation frequencies, and six channels
each
can
be
programmed
into
the board
for
transmit and receive.
+6V
is
applied
to
each
channel line, one
of
receive channels 1 - 6 and transmit channel 1 - 6, through
the
channel select switch, and
it
is
converted
to
BCD
codes
by diodes programmed
into
the board, then
fed
to
IC201
to
determine
an
operation frequency.
When
duplex transmit
function
is
required, calculate
each
N value
for
transmit frequency and receive
frequency and program diodes
into
the board independently.
The receive
only
function
is
provided
for
channel 2 - Channel 6 by inserting a diode
into
the receive
only
line.
At
this time, a voltage
is
applied
to
the
base
of
0107
on the
MAIN
board through R404, and
it
turns
0107
ON and
0106
OFF. Thus, the
set
does
not
turn
to
the transmit mode,
even
if
the PTT
switch
is
depressed.
Crystal Frequency Chart
Operating Frequency
Range
Crystal Frequency (MHz)
Local Oscillator
X202
(Receive)
X203
(Transmit)
Frequency (MHz)
150.005
- 155.000MHz
32.02625 36.25125 145.005
155.005
- 160.000M Hz
33.27625
37.50125 150.005
160.005-
165.000MHz 34.52625
38.75125 155.005
165.005
- 170.000M
Hz
35.77625
40.00125 160.005
NOTE: The
local oscillator frequency
for
calculation N value
is
the
four
times
of
the crystal frequency.
3-4
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