Receiver Functional Blocks; Input Filter; Rf Preamp M1406A - Philips 50 T Series Service Manual

Receiver Functional Blocks

Receiver Functional Blocks

Input Filter

RF Preamp M1406A


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.
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.
Chapter 9 - Theory of Operation