Crown FM250G User Manual page 4

Rev A
3.6 RF Output Control....................................................................................... 3–6
3.7 Digital Multimeter ....................................................................................... 3–6
3.8 Fault Indicators ........................................................................................... 3–7
Section 4—Principles of Operation
4.1 Part Numbering .......................................................................................... 4–2
4.2 Audio Processor Circuit Board.................................................................... 4–2
4.3 Stereo Generator Circuit Board ................................................................... 4–4
4.4 RF Exciter Circuit Board.............................................................................. 4–5
4.5 Metering Circuit Board................................................................................ 4–6
4.6 Motherboard............................................................................................... 4–8
4.7 Display Circuit Board .................................................................................. 4–8
4.8 Voltage Regulator Circuit Board.................................................................. 4–9
4.9 Power Regulator Circuit Board ................................................................. 4–10
4.10 RF Driver .................................................................................................. 4–11
4.11 RF Amplifier.............................................................................................. 4–11
4.12 Chassis and AC Supply............................................................................. 4–11
4.13 RF Output Filter & Reflectometer .............................................................. 4–12
4.14 Receiver Circuit Board Option................................................................... 4–12
Section 5—Adjustments and Tests
5.1 Audio Processor Adjustments .................................................................... 5–2
5.1.1 Pre-Emphasis Selection ......................................................................... 5–2
5.1.2 Pre-Emphasis Fine Adjustment .............................................................. 5–2
5.2 Stereo Generator Adjustments.................................................................... 5–2
5.2.1 Separation .............................................................................................. 5–2
5.2.2 Composite Output .................................................................................. 5–2
5.2.2.1 Using a Modulation Monitor ............................................................ 5–2
5.2.2.2 Using Bessel Nulls ........................................................................... 5–3
5.2.3 19–kHz Level.......................................................................................... 5–3
5.2.4 19–kHz Phase......................................................................................... 5–3
5.3 Frequency Synthesizer Adjustments ........................................................... 5–3
5.3.1 Frequency Channel Selections................................................................ 5–3
5.3.2 Modulation Compensator ....................................................................... 5–4
5.3.3 Frequency Measurement and Adjustment .............................................. 5–4
5.3.4 FSK Balance Control............................................................................... 5–4
5.4 Metering Board Adjustments ...................................................................... 5–4
5.4.1 Power Calibrate ...................................................................................... 5–4
5.4.2 Power Set............................................................................................... 5–4
5.4.3 SWR Calibrate ........................................................................................ 5–5
5.4.4 PA Current Limit..................................................................................... 5–5
5.5 Motherboard Adjustments .......................................................................... 5–5
5.6 Display Modulation Calibration ................................................................... 5–5
5.7 Voltage Regulator Adjustments .................................................................. 5–5
5.8 Performance Verification ............................................................................ 5–6
5.8.1 Audio Proof-of-Performance Measurements.......................................... 5–6
5.8.2 De-emphasis Input Network................................................................... 5–6
5.9 Carrier Frequency ....................................................................................... 5–6
5.10 Output Power.............................................................................................. 5–6
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FM250G User's Manual