C Andersson wrote:

>> a reference to a BESSEL BANDPASS filter.

There's a nice software called "Filter Wiz Pro" which can be downloaded at:
http://www.schematica.com/Fil_Xfer/Transfer.htm

The unregistered version has some masked componet values in the circuit 
diagrams.

73
Christer
sm6pxj

Thanks for the URL info.  I will check it out.

Bob ZL2CA