Tube Radio Forum
Would you like to react to this message? Create an account in a few clicks or log in to continue.

Philco model 49-505

2 posters

Go down

Philco model 49-505 Empty Philco model 49-505

Post by Ed in W. PA Mon Sep 15, 2014 10:48 pm

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

Number of posts : 129
Registration date : 2014-02-17

Back to top Go down

Philco model 49-505 Empty Re: Philco model 49-505

Post by Dr. Radio Tue Sep 16, 2014 3:57 pm


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. Smile
Dr. Radio
Dr. Radio

Number of posts : 899
Age : 41
Registration date : 2012-09-17

Back to top Go down

Back to top

Permissions in this forum:
You cannot reply to topics in this forum