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TRC-70
CIRCUIT DESCRIPTION
Loop B generates a 37.5~39.5 MHz signal via IC6
Frequency
(CXD1225M) with a 1 kHz comparison frequency. The _| Function
O.1~7MHz | 7~14MHz | 14~22MHz | 22~3OMH2
37.5~39.5
MHz
signal is generated by VCO6
(X59-
Microprocessor | V1
0
1
0
1
3440-00), then divided by 100 in C7 : M54459L to gen-
control signal | V2
0
0
1
1
erate a 10 Hz steps.
Fine-frequency adjustment by
means of the clarifier is added to loop B under micro-
processor control. The 375~395 kHz output signal that
was divided by 100 by IC7 is mixed with the 30.3 MHz
BPF
BPFI | BPFI | BPF2
signal by IC8 : SN16913P
in order to generate a
w o
a s
BPF2
(SN76514N).
Loop A generates a 71.395~ 101.295 MHz signal via
IC3 (CXD1225M) with a comparison frequency of 20
J3E USB. CWR. H3E=10.6965MHz
kHz.
This signal becomes the HET oscillator signal.
manana
ae So coese
The loop A VCO (X58-3720-10) consists of four sepa-
rate VCO circuits which are selected by IC4 (TC4028)
AMP {
FILTER
according to the control data from the microprocessor.
UNLOCK —sf 22?
cri
(See Table 1.) Part of the loop A VCO output passes
2sc2714 {Y)
through the buffer amplifier of Q9 : 28C2714(Y) and is
LPF
mix 4
applied to |C5. The signal is then mixed with the signal
x
1c11
from loop B in IC5 : SN76514N (40.72~70.62 MHz).
~~
SN16913P
The resulting 40.72~70.62 MHz signal passes through
v0}
10.1MHz
BPF1
and BPF2.
VCO1
and VCO2
pass the signal
through BPF1, and VCO3 and VCO4 pass it through
Wet a50L
BPF2. The signal passing through the BPF is amplified
(CXD1225M) with a 2 kHz comparison.
This VCO out-
signal passes through ceramic filter CF1 to become
—_—
|— ——
—f—
the CAR signal.
The CAR signal changes with the
[
L
TX-RX unit.
| N=29650~29850
{
1
|
|
|
1/5100
|
|
| Ic9 : CXD1225M
Fig. 3 Block diagram of PLL CAR loop
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