BSR450 IF filter retrofit 
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Nokia BSR450 IF filter exchange test

CFG455G = +-4kHz, CFK455F8 = +-6kHz.

Replacing the filter dropped FM distortion from 4% to 1% at 3kHz deviation. Good start.

Original BSR450 IF filter layout. Notice components L107 and R137 on left side of the 455kHz filter
Original BSR450 IF filter layout. Notice components L107 and R137 on left side of the 455kHz filter

Solder side of the board untouched. 455kHz filter sits in the middle.
Solder side of the board untouched. 455kHz filter sits in the middle.

BSR450 with new 455kHz filter fitted in. L107 and R137 needed to be removed and are at the solder side
BSR450 with new 455kHz filter fitted in. L107 and R137 needed to be removed and are at the solder side

L107 and R137 located on the solder side of the board after fitting the too-big IF filter. Notice a drilled hole for one leg of the filter right of R137
L107 and R137 located on the solder side of the board after fitting the too-big IF filter. Notice a drilled hole for one leg of the filter right of R137

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