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28
Transmitter Alignment
transmitters with Pre-emphasis and CtCSS Subtone
Section a: Balanced and Subtone audio Setup
Step
Reference
1.
R2 (Mic I/P)
R29 (Deviation)
R31 (Balanced)
R38 (Compress)
R42 (Subtone1)
R63 (Mic Comp)
R36 (TCXO)
2.
Balanced Input
P1-1 and P1-2
3.
R29 (Deviation)
4.
Subtone 1 input
5.
R42 (Subtone1)
6.
OST-3H035-(2-Port)
OST-3H045-(2-Port)
7.
R36 (TCXO)
8.
Subtone 1 input
9.
Deviation Monitor
10.
Deviation Monitor
11.
Balanced Input
P1-1 and P1-2
12.
R38 (Compress)
13.
AF Gen.
14.
R31 (Balanced)
15.
AF Gen
16.
R31 (Balanced)
MT-3 FM Transmitter Mainboard Instruction Manual
IM20-MT3TXMN
Action
Turn Fully CW.
Turn Fully CW.
Turn Fully CW.
Turn Fully CW.
Turn Fully CW.
Turn Fully CW.
Turn Fully CCW.
Set AF tone freq,
level and filter.
Adjust R29 for deviation.
Do not re-adjust.
Apply tone.
Adjust and measure.
Change AF Gen. freq.
Adjust and measure.
Change AF Gen. freq.
Should measure.
Sweep AF Gen. freq.
between 67 Hz and
250 Hz. Measure
resultant deviation.
Change frequency and
level.
Adjust and measure.
Change level
Adjust and measure.
Change level.
Measure and confirm.
Desired Results
Notes
AF Filter: Low Pass
5 kHz or 15 kHz
AF Gen:
1.8 kHz @ +10 dBm
± 4.4 kHz
AF Gen: 1 kHz Tone @ -18 dBm
± 500 Hz
Deviation Monitor
AF Gen:
40 Hz @ -18 dBm
± 500 Hz
AF Gen:
300 Hz @ -18 dBm
500 Hz
Tolerance on this
measurement is ± 50Hz
± 300 Hz to 700 Hz
AF Gen: 1 kHz Tone @
+10 dBm
Distortion Analyzer
AF Filter: 15 kHz
4.0% THD
1 kHz Tone @ -8 dBm
± 3 kHz
Deviation Monitor
1 kHz Tone @ -18 dBm
± 1 kHz
Tolerance on this
measurement is ± 50 Hz
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