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i
2-5 Band switching
circuit
The band switching control signals are output from pins 36, 37 and 38 of the CPU and fed
to the base of Q1 03, Q104 and Q1 05, band switching transistors.
The one of these transistors then supplies the drive voltage(+l 2V) to the tuner according to
the output signal from the CPU as shown below table.
Antenna
I._
Tuner
VL
VH
u
Cllo3
12k
Q104
12k
Q105
R898
12k
Band Switching Logic
output
Pin36
Pin 37
Pin 38
Q103
Q104
Q105
Selected Band
LH
H
on
off
off
VHF-Low
HL
H
off
on
off
VHF-High
HHL
off
off
on
UHF
36 VL
37 VH
38 UHF
CPU
-12-
Tmining
Manual
AC1 Chassis
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