Studebaker S4927 Radio: S4927 Restore

This is a near full restore of a S-4927 Philco radio for a Studebakers Of Southern Oregon (SOSO) member Keith Bartlett. Radio was is fair condition and actually made noise out the speaker indicating a lot functioned. Here is a list of problems I encountered:

1. Speaker cone was warped from water exposure and the voice coil was rubbing.
2. Antenna input tuning coil damaged.
3. RF and oscillator tuning coil slugs loose.
4. Decomposed speaker grill seal.
5. Tuning mechanism gummed up with grease.
6. Tuning mechanism out of alignment.
7. Tuning coil form mounting rubber grommets decomposed.
8. Need of general cleaning.
9. Missing bezel and knob paint.

The speaker was sent off to Weber Speakers for reconing:

Weber Speakers
405 E. Southway Blvd.
Kokomo, IN 46902
https://www.tedweber.com
orders@tedweber.com

They didn't have any 4 ohm voice coils so they ended up using an 8 ohm coil. No real big difference.

I got into the Antenna input tuning coil and discovered that one terminal was pulled out of the coil form. Easy to fix except that the wire was broken off at the base of the coil and could not be connect to so I decided to research rewinding the coil. The coil was wound using Litz wire. Litz wire is a wire made up of many strands individually insulated and wound together is one insulation wrap. This wire was composed of 7 wires of 42 AWG wire. I know the coil is 12 ohms so a little math is needed to determine the length needed:

42 AWG wire is 1,801 ohms per 1,000 feet. Since there is 7 in parallel:

1/1801 + 1/1801 + 1/1801 + 1/1801 + 1/1801 + 1/1801 + 1/1801 = 1/0.0038867295946696 = 257.2857142857143 or ~257 ohms per 1,000 feet or 0.25‬ ohms per foot

We know the coil is 12 ohms so: 12 / 0.25 = 48 feet is needed to wind the coil.

Of course I could not get that exact wire but I did find 5/41 Litz wire...
So, back to the math:

41 AWG wire is 1,477 ohms per 1,00 feet. Since 5 are in parallel:

1/1477 + 1/1477 + 1/1477 + 1/1477 + 1/1477 = 1/0.003385240352065 = 295.4 or 0.2954 ohms per foot

We know the coil is 12 ohms so: 12 / 0.3 = 40.6 feet is needed to wind the coil.

So I ordered some 5/41 Litz wire. After some thought I realized that I have a bunch of parts when I did the 10 M-truck radio restore. I found a coil with the same size and resistance that would work perfect. I still plan to wind that coil just to know it can be done and function correctly.

Distorted speaker cone

Reconed speaker

Decomposed and patched speaker grill gasket

New tuning coil form rubber grommets

Restored tuning coils

Replaced all paper capacitors with Orange Drops, Replaced all resistors, re-canned new electrolytic capacitors, replaced vibrator with solid state circuit from Aurora Design (re-canned). Since Mica and ceramic capacitor do not age like paper capacitors I left them.