Kenwood TH-28A Service Manual page 21
144mhz fm transceiver
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Also See for TH-28A:
- Service manual (78 pages) ,
- Instruction manual (65 pages) ,
- Manual (60 pages)
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TH-28A/E
SEMICONDUCTOR DATA
FM Receiver IC : MC3372D (TX-RX unit IC1)
¢
Block diagram
GND
PP
od Pe
|
AF
KE
AMP.
O PD
SQUELCH
;
aa
TRIGGER
LIMITE!
AME,
| OSCILLATOR
|
3
CT el el eo
ol oT oy
.
Vec
¢« Terminal functions
+-Pin-No.—\-~Pinname
Description
1
OSC In
The crystal oscillator is connected to this pin to form a Colpitts oscillator.
If an external oscillator is used,
2
OSC Out
input to pin 1, and connect pin 2 to Vcc.
;
3
MIX Out .
Mixer output pin.
4
Veco
Power supply pin.
5
LIM In
Limiter amplifier input pin and decoupling pin. AC-couple pins 6 and 7.
8
DECI
,
7
DEC2
8
QUAD In
Phase-shifter connection pin.
9
AF Out
FM detector signal is output.
10
Famp. In
Operational amplifier inverted input pin.
11
F amp. Out
Operational amplifier output pin.
12
SQSW in
Squelch switch input pin.
43d
Smeter Out'
p The' current correspondirig tothe limiter amplifier iAput signal level is output
14
SOSW Out
Squelch switch output pin.
15
GND
Ground pin.
16
MIX In
Mixer input pin.
21
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