[DuMont]

I've finished the electronic restoration of the Philco 46-480 and while AM plays well, FM volume is very low even with volume turned to high.  The 7F8 tube is good, and I discovered a 4.7 uf instead of a 5 mf electrolytic in the 2nd IF stage.  Going to put the correct value in there, but what's really got me interested is a jack on the back of the chassis that says "FM Test Socket" and looks about the size of an iPod headphone jack.  I can find NO REFERENCE to this in the Philco service manual, Riders, or Sams.  Any idea what this is and what it's supposed to do?

[morzh]

4.7uF is a correct value.

[DuMont]

Well, it's all up and working, but the FM volume is still low.  Have to crank the volume control knob to max.  I have the two wire "antenna" that Philco supplied with the radio (it plugs into the chassis and the two wires are stapled along the inside of the cabinet) but I'm wondering if longer wire, or even a pair of old rabbit ears, might give me better FM reception.
AM is perfect, even got the five push buttons programmed for favorite AM stations.  Still wondering about that FM "test socket" on the back of the chassis.

[Jake Blake]

I started to say you might have a hard time finding a 5mfd electrolytic  capacitor for that exact value, and that Morzh's comment about it being a correct value is because , for all practical purposes, a 4.7 should suffice for the 5.0 value.  The distributors will tell you that also.

. . . . but I notice JustRadios.com does, indeed,  have a 5mfd electrolytic, rated at 600 volts.  I was careful to get my exact filter values also, even though it meant buying a couple with higher voltage ratings.  I can get picky that way sometimes, also.  

Trouble is, their $20 minimum order.  Hope you can come up with more you need to make it worth it.