Philco model 49-505
Philco model 49-505
I am re-caping a Philco model 49-505 and have a question concerning one of the capacitors. C 302 is connected between the B- line and the chassis. It is a IF bypass capacitor and is marked .2 mfd @ 400v and is marked "special construction". The schematic shows it as a coil and capacitor in series. The text of the Riders schematic describes this cap as being inductively wound to form a series tuned circuit resonant at the intermediate frequency offering less impedance at this frequency thus permitting higher IF gain. Does anyone have any experience with this? The cap I have is leaky and must be replaced, and I need to come up with a replacement. Any input would be greately apreciated. Thanks, Ed.
Ed in W. PA- Member
- Number of posts : 128
Registration date : 2014-02-17
Re: Philco model 49-505
Ed,
Simply replace it with a regular cap. Read that modern cap. A safety "y style" would be ideal to prevent the typical AC/DC chassis shock hazard. You won't find a "y safety cap" in that large of a value....but for testing, a regular cap will do.
Back in the day ship/shore stations transmitted around the same IF frequency and this cap was to "bleed" off any unwanted interference from such xmitters as not to get into the radios IF stages. Today it's a non issue.
Go ahead and try it.
Simply replace it with a regular cap. Read that modern cap. A safety "y style" would be ideal to prevent the typical AC/DC chassis shock hazard. You won't find a "y safety cap" in that large of a value....but for testing, a regular cap will do.
Back in the day ship/shore stations transmitted around the same IF frequency and this cap was to "bleed" off any unwanted interference from such xmitters as not to get into the radios IF stages. Today it's a non issue.
Go ahead and try it.

Dr. Radio- Member
- Number of posts : 899
Age : 40
Registration date : 2012-09-17
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