The schematic I posted of a simple single tone "Make and Break" keyer needs a slight correction. The printer magnet drawing that depicted parallel configuration is in error. The coils in parallel  need to be wired so that one of the coils is out of phase to prevent "Bucking" of the field.
BTW a Range Filter such as the military FL8  on the input served as a filter but is not needed when using a "Rice Box" receiver with all its filter options.
k4che