04-15-2010, 08:04 PM
Actually this is not a 'wavetrap' in the reception sense of the word. Philco apparently recognized that they were not bypassing IF frequencies to ground very effectively due to the inductance of the old foil wound caps. The solution was to add more inductance in series to 'tune' it to 455 for better bypassing at that frequency. Its all explained on Chuck's site.
Since modern caps don't have the same issue as the big old paper caps the coil is no longer required.
Since modern caps don't have the same issue as the big old paper caps the coil is no longer required.