Building a BitX 20 Radio
The BitX 20 is a 20m band SSB transeiver originally designed in India by Ashar Frahan, and now supported and developed by by many people. My BitX is a version 3, built on a PCB ordered from Sunil Lakhani VU3SUA.
Band Pass Filter
The BitX bp-filter is simply constructed from three Toko coils and a handfull of NPO capacitors.
Quickly peaking up the filter response using the variable cores on the Toko coils give the following filter plots.