GSS HRM 325, Руководство по сборке

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4 Setting the cassette
In order to prevent interference, too high signal levels, e. g. of local transmitters,
can be reduced by absorption circuits.
• Switch on the head-end station.
—> The display shows the following indication for the FM amplifier.
• Connect a spectrum analyser to the HF output of the head-end station.
• Set ”
input level regulator ” to the mechanical centre.
• If necessary tune the absorption circuit groups ” Traps 1 … 3 ” and ” Traps 4 … 6 ”
to the frequencies to be lowered.
—> You can lower 3 interfering frequencies each with the absorption circuit
groups ”
Traps 1 … 3
” and ”
Traps 4 … 6
”. If the adjustment range of an
absorption circuit, for example from group ” Traps 1 … 3 ” is inadequate,
you can lower the frequencies even further with an absorption circuit that
is tuned to the same frequency from group ”
Traps 4 … 6 ”.
Box 1 FM
87 – 108 MHz UKW
+
Traps
4 … 6
Traps
1 … 3
Input level
regulator
Example of the progression of the tunable acceptor circuits
0 db
-4 db
-8 db
-12 db
-16 db
8 0 1 4 0 1 5 , 1 9 5 , 7 8
-14 db
-17 db
in MHz
Frequency