Crown FM150, Руководство пользователя

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4.13 Chassis
The AC power supply components, as well as the bridge rectifier and main filter capacitor,
are mounted on the chassis. Switching in the power-entry module configures the power
transformer for 100, 120, 220, or 240 VAC; see section 2.2 for switching and fuse informa-
tion. A terminal strip with MOV voltage-surge suppressors and in-rush current limiters is
mounted on the chassis between the power entry module and the toroidal power trans-
former.
The main energy-storage/filter capacitor, C01, is located between the voltage and power
regulator boards. The DC voltage across the capacitor will be 45–55 volts (FM30 and
FM150) or 65–70 volts (FM300) when the carrier is on.
4.14 RF Output Filter & Reflectometer
The RF low-pass filter/reflectometer are located in the right-hand compartment on the top of
the chassis. See Illustration 6–13 and accompanying schematic for more information.
A ninth-order, elliptic, low-pass filter attenuates harmonics generated in the power amplifier.
The capacitors for the filter are circuit board pads.
The reflectometer uses printed circuit board traces for micro-strip transmission lines. Trans-
mission line segments (with an impedance of about 82 ohms) on either side of a 50–ohm
conductor provide sample voltages representative of the square root of forward and reverse
power.
DC voltages, representative of forward and reflected power, go through a bulkhead filter
board to the motherboard, then to the metering board, where they are processed for power
control and metering and for SWR metering and protection.
4-14 FM30/FM150/FM300 User’s Manual