Kenwood TH-22A Service Manual page 14

TH-22A/AT/E
CIRCUIT DESCRIPTION
14
SUPPLIED CIRCUIT
e CTCSS
The tone frequency is set by the serial data from the
microprocesser (!C206). The audio input signal is the detec-
tion output input from the Cl pin.
The SDO pin is made fow when the tone frequency coin-
cides. The microprocesser determines the SDO pin state
and controls the MUTE, AFCO, AFC1 pins.
When the CTCSS signal is transmitted, the CTCSS is out-
put from the microprocesser and modulated.
¢ DTSS
A DTMF code is input or output as serial data of micro-
processer. The aucio input signal is input from the Cl pin in
the same way as in CTCSS. The data is sent to the micro-
processer when a DTMF signal is detected. The microproc-
esser determines the coincidence of the code and controls
the MUTE, AFCO, and AFC1 pins.
* The DTMF signal is output from the microprocesser during
DTMF signal transmission. The DTMF signal is modulated
through the microphone amplifier During DTMEF signal trans-
mission, the MUTE pin is made low and the microphone
signal is muted. AFCO and AFC1 are then turned on, and the
DTMF signal can be monitored with the speaker.
CONTROL
KEY BOARD
V12)3iA | MIG AMP
4166/8 MIC 16207
7la{a|c +
xlol#elo
a
_| azog
V7 1C201
Pp Pp AUDIO
sp = pO INPUT
STD STD Cl
CK CK
32. LPF ale
cay] ENTS
77)
oom om
TOC
ror 22
arci 2
arco 440
mute /22
CK,DT,ET 7
SP
spo
ee | —_~
C D)
\Z
OQ. SEF OE
a oaw ae
. zz
1C1 AK2344
TSU-8
CTCSS UNIT
Fig. 15 Supplied circuits connection diagram (DTMF, CTCSS, BEEP, TONE)