Philips 50 T Series, Руководство по обслуживанию

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Receiver Functional Blocks
Chapter 9 - Theory of Operation
Receiver Functional Blocks
Input Filter
This module builds up a highpass filter with <1dB loss in the useful
frequency range 406 to 470 MHz and >20dB rejection for 100 MHz signals.
It prevents overloading of the RF preamplifier with strong lower frequency
signals.
The filter also provides the preamplifier with a 21V DC power by coupling
this DC voltage into the hot wire of the preamplifiers input cable. A
capacitor decouples the DC power from the antenna input.
RF Preamp M1406A
This MAGIC line amplifier boosts the input signal by 12 dB. This results in
an input sensitivity of about -118 dBm together with the M1402A RF
Receiver. The amplifier is powered from the DC power at the hot wire of the
input coax cable.