3 - 14
13
14
15
16
17
18
19
Outputs strobe signals for the out-
put expander ICs (RF-B unit; IC301, 
IC302).
Outputs the antenna connector 
([ANT1] or [ANT2]) select signal.
 High :  When the [ANT2] is selected.
Outputs strobe signals for the output 
expander (CTRL-A board; IC11).
Outputs strobe signals for the D/A 
converter (IC3751).
Outputs strobe signals for the output 
expander ICs (IC3752, IC3753).
Outputs control signal for the AF mute 
switch (IC331).
 High :  When the [AF] control is set to 
maximum counter clockwidth.
Outputs squelch mute control signal, 
applied to the squelch gate (IC301).
  High : When squelch is closed.
BSTB
ANTS
FSTB
ASTB
MSTB
AFMS
SQLS
 Pin  Port 
Description
 number  name
12
13
14
15
16
17, 18
Outputs squelch control signal for the 
[MIC] and [ACC1] connectores.
 High :  Squlch opend. (RX LED ON)
Outputs control signal for the internal 
speaker ON/OFF select relay (RL351).
  High : Internal speaker is ON.
Outputs strobe signals for the optional 
UT-102 SPEECH SYNTHESIZER.
Outputs chip select signal for the 
audio recoder (IC3001).
Outputs external antenna tuner (AH-3) 
start signal.
 Low :  When the [TUNE] switch is 
pushed.
Outputs control signal for the DSP IC 
(DSP-A board; IC2001).
SQSS
SPS
SSTB
VCS
ESTA
DSFR,
DSFW
 Pin  Port 
Description
 number  name
4
6
7
12
14
Outputs control signal for the noise 
blanker switch (Q3751, Q3752).
 High :  When the [NB] switch is ON, 
except in FM mode.
Outputs audio select signal for the TX 
monitor function.
 High :  During monitoring in SSB or 
RTTY mode.
Outputs audio select signal for the TX 
monitor function.
 High :  During monitoring in AM or FM 
mode.
Outputs analog switch (IC3005) con-
trol signal for the audio recoder’s 
(IC3001) output.
 High :  When the audio recoder’s out-
put to the AF circuit.
Outputs analog switch (IC3002) con-
trol signal for input of the microphone 
amplifier (IC461).
 High :  Except the microphone input is 
selected.
NBS
MSL1
MSL2
VOSL
MISL
 Pin  Port 
Description
 number  name
4
5
6
7
11
14
Outputs AM mode select signal for 
the AGC and APC circuit.
  High : When AM is selected.
Outputs HF band RF power control 
signal.
 High :  When 0.03–29.999999 MHz 
band is selected.
Outputs 50 MHz band RF power con-
trol signal.
 High :  When 30–60 MHz band is 
selected.
Outputs 2nd IF filter (FI131 or FI133) 
select signal.
 High :  When transmitting in AM or FM 
mode. (FI131 is ON)
Outputs reset signal for the DSP cir-
cuit and etc.
Outputs FM deviation control signal.
  High : When FM-N is selected.
AMS
PHFS
P50S
MODS
DSRS
FMNS
 Pin  Port 
Description
 number  name
(8) MAIN-A unit; IC3653
(10) MAIN unit; IC3752
(9) MAIN-A unit; IC3654
(11) MAIN-A unit; IC3753