Icom IC-F21S Two-Way Radio User Manual


 
4 - 5
Pin
number
61
62
Port
name
BDET
BATV
Description
Input port for the battery’s type detec-
tion.
Input port for battely voltage detection.
4-5-3 D/A CONVERTOR IC (IC9)
Pin
number
2, 3,
10, 11
14
15
22
Port
name
T1–T4
REF
BAL
DEV
Description
Output tunable bandpass filters con-
trol signals.
Outputs differential voltage for the ref-
erence oscillator (Q31, D19, X1).
Outputs DTCS balance control signal.
Outputs modulating signal for the
modulator circuit (D6).
CPU (IC7)–continued
4-5-2 OUTPUT EXPANDER IC (IC15)
Pin
number
4
5
6
7
11
12
13
14
Port
name
CSFT
RMUT
MMUT
DUSE
T5C
R5C
S5C
NWC
Description
Outputs clock shift control signal for
CPU.
Outputs RX mute control signal.
Outputs TX mute control signal.
Outputs low-pass filter cut-off frequen-
cy control signal when DTCS is acti-
vated.
Outputs T5 regulator control signal.
Low: While transmitting.
Outputs R5 regulator control signal.
Low: While receiving.
Outputs S5 regulator control signal.
Low: While power is ON.
Outputs Narrow/Wide of channel
spacing control signal.
Low: While Narrow is selected.