Important for City Dwellers!
The NE602 cannot handle very strong signals without problems.
In some city environments very strong broadcast stations can ride through the input coil and get into the NE602. Strange sounding signals will appear while tuning the receiver.
The filter can be built dead-bug style on a piece of PCB and placed immediately at the antenna input if the receiver is put in a box. Or it can be built on the prototype section.
The broadcast filter is from most of the recent Amateur Radio Handbooks ("A BC-Band Energy-Rejection Filter", Filters and Projects, The ARRL Handbook, 1999, pp 16.36).
The article in the ARRL Handbook shows a layout and how to modify the filter for different frequencies. Very simple to understand and follow.
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