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TUNING VOLTAGE GENERATOR
BT
BS
VCC6
This circuit generates the DC tuning voltage BT for selecting a channel with a TU pulse being output from
IC700.
IC500 has 3 circuits for converting pulses to voltages; it selects one of VHF-L, VHF-H, or UHF, and
causes the tuning voltage to be output from the OUT terminal (pin 12). Figure 2 and Table 1 show the
conditions for selection.
VHF
-L
11
VHF
TU
-H
UHF
CIRCUIT DESCRIPTION
IC500 MSC1169MS-K
Figure 1
IC500
9
10
U/V H/L
Figure 2
— 3 —
Inputs
U/V
H/L
L
L
12
L
H
OUT(BT)
H
L
H
H
TU
H/L
BU
VREF
GND
Function
VHF-L receiving
VHF-H receiving
UHF receiving
UHF receiving
Table 1
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