[Joe Rossi]

Good Evening!  I'm working on a Philco 49-902 and the replacement parts list has a "Condenser, i-f by-pass (inductively wound) .1 mf". Internet search says that it was to filter out signals from 400-500kc. IF thats correct, can I replace with a standard poly .1uf or even a safety cap?  Thanks, Joe

[RodB]

Hi Joe,

From your description, I'm guessing it's the Philco IF trap where a coil of 8 turns is wrapped around a 0.1mfd capacitor (from memory, I'm thinking a smaller value) and wired in series with it. This creates a series resonant circuit of about 455kHz, shorting stray interfering IF signals to ground. You can either duplicate the part or just use the capacitor alone or leave it out of the radio. Sometimes having it in removes some of the noise interference. A poly cap is fine. Safety cap is much more expensive for this purpose.

[Joe Rossi]

Thanks for the help.  I thought a ploy cap would be fine, but me and thinking don't always do very well .  On the Philco Repair Bench under Service Tips, I-F Wave Trap & Special Capacitor, it 'splains that the later wave traps have the coil inside the paper capacitor.  Go figure. Now I have a .1uf Sprague Orange Drop in its place.  I'm saving the original Philco Special, just in case. Thanks again,  Joe