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fm audio Processor Block diagram
Microphone
Input
Compression
Amp
P1-3
Pre-
R2
emphasis
U1A
Select
Balanced
Input
Compression
Amp
P1-1
Pre-
JU11
emphasis
U1B
R31
Select
Auxillary
Buffer
Amp
Pre-
R48
emphasis
U2C
Select
P2-1
Inverting Amp
JU12
Tone
Digital
U2D
Input
Subtone
1
P2-2
R42
Subtone
2
JU13
P4-1
JU4
JU28
Direct Modulation
Offset Buffer
JU30
U2B
P4-3
JU43
Offset
Coupling
Select
R87
Direct
Modulation
Input
+4 V
Regulator
U2A
Limiter/Summing
Amplifier
U3B
U3A
Buffer
U5
49K9
3dB
Narrow
U6
Band
Pad
49K9
JU14
JU25
JU26
2 Port
Polarity
Select
JU27
+4 V
Splatter
Filter
3 KHz
Regular Modulation
Audio
Buffer
Switch 1
U3D
Modulation Buffer
JU34
Audio
Switch 2
JU35
Tx Audio
Control
Q1
MT-3 FM Transmitter Mainboard Instruction Manual
Theory of Operation
Reg Mod
P3-1
Out
TCVCXO
Low Freq
Out
U3C
P4-2
TCVCXO
R36
DC Level
Adjust
*
Tx Audio
Control
P4-4
B0232
FIGURE 1
IM20-MT3TXMN
13
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