[R-390] Filters

[mlmccauley at att.net]

A DSP filter would be an ideal replacement for a mechanical.

DSP chips that work at 455KHz are readily available for very reasonable $.

The problem is the software.  To do a nice, flat topped, steep skirt 
filter would not be a trivial piece of work.

The upside is that one relatively simple circuit could be made to do 
everything from super-narrow CW to full bandwidth AM SWL.

73,

Mike, WB5MYY