2-10
3.3 AF (05P0704)
The AF Board consists of the ALC amplifier circuit for the signal from the handset microphone, and the
AF amplifier circuit (2 channels volume control circuits) for the line input signal from the MF/HF
radiotelephone and beep sound.
INST signal is input to the CONTROL/MODEM board from “J5#3”. The Main CPU recognizes the
presence of the AF board using this signal and enables remote control of the MF/HF radiotelephone.
Which line output signal, of DSC or of handset, is connected to the MF/HF radiotelephone is switched
by the signal “J5#4:SSB”. This signal is switched at DSC transmission or output of audio alarm.
Adjustment of microphone lineAdjustment of microphone line
Adjustment of microphone lineAdjustment of microphone line
Adjustment of microphone line
1) Turn “R9, OUT LEVEL” fully clockwise, “R7, COMP.” fully counterclockwise, and set
microphone input signal at 1.5kHz. -46dBm, 600 ohms.
2) Adjust “R2, MIC GAIN” for line output level of 3.1Vp-p. (Check point J3#1)
3) Adjust “R9, OUT LEVEL” for line out level of 2.2Vp-p. (Check point J3#1)
4) Set the input at -30dBm and adjust “R7, COMP.” for line out level is of 4.4Vp-p.
When the microphone line is adjusted as shown above, the compressor activates at -40.5dBm
approximately.
3. Function and overview of each board
AF block diagramAF block diagram
AF block diagramAF block diagram
AF block diagram
R7
R9
R5
C5
R2
U1 M51304L
COMP OUT LEVEL
TIME
OUT2
OUT1
Vc1
IN2
IN1
Vc2
FB
1/2
MIC GAIN
SSB
SSB
DSC
DSC
J3-1 LINE OUT
J3-3 LINE IN
J4-1 LINE OUT
J4-3 LINE IN
J5-9 BEEP
J5-8 Vc2(HS)
J5-7 Vc1(SP)
J5-4 SSB
J5-5 PTT
J5-6 HOOK
J5-3 AF INST
J5-1 +15V
J1-2 PTT
J1-3 MIC
J1-5 PHONE
J1-6 HOOK
J2-1 SP
TDA2003H
2/2
U2: NJM4558M
U4 M5207L05
1/2,2/2
1/2,2/2
U5
U5
U5
5
6
12
13
DSC
SSB
U7
U8
U2
U9
U2
U3
Q1 Q2
Q1/2: DTA114ESA
U7/8: NJM2904M
3W 4 ohms
T1
T2
MODEM
MF/HF Radiotelephone
LINE IN/OUT
CONTROL
CONTROL/MODEM
(05P0702)
J8
J9
+15V
0dBm/600 ohms
0dBm/600 ohms
MIC: -46dBm/600 ohms
PHONE: 1mW/200 ohms
HANDSET
SPEAKER
U9:NJM386M
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