I am attempting a restoration of a Philco 60. Circuit diagram is at
http://www.philcoradio.com/tech/60evol.htm. I have the Aug 15, 1934 version.
The volume control was replaced at some time in the past with a 750k unit. The circuit diagram shows this should be a 350k unit. Also, the 78 tube shield is missing. Will these items make a difference in performance and should I be looking for replacements?
Thanks, Bob
You can connect a 470K fixed resistor in parallel across the ends of the volume pot so that the detector circuit will see approximately 350K. The actual value presented to the grid of the 75 audio stage by the sliding contact is not critical. I doubt you would notice any difference.
The radio will work without the shield on the 78, but for best performance you would eventually want to find a replacement for it.
I have completed replacing all the caps and out of spec resistors in this radio and added a resistor parallel to the volume control as suggested by Mondial. Also, the oscillator and antenna coils were rewound.
I aligned the radio today and it is working. I am able to pick up local stations satisfactorily but nothing that is 60 or 70 miles away. I only have an antenna that is about 30 feet long and am wondering if this could be the problem or should I be looking someplace else.
I do not have the tube shield for the 78 tube yet. Does the presence of the shield affect alignment? What kind of problems occur with no shield in place?
Thanks, Bob