[whirligig]

We just finished electrically restoring a Philco 37-60 but it has no tone control. The original on/off switch with two tone position switch was replaced with a pot that has an on/off switch. The tone caps were never hooked up so there is no tone control at all. The owner has told us a replacement will be very hard to find. Instead, he wants to see if we can make the pot arrangement work. Before I start bread boarding a circuit for this, has anyone ever converted a fixed tone control to a variable one? Is there a circuit I can use?

Thanks.
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Update: After repairing another issue with this radio, I revisited the tone control. Thanks to Mike, his tone control design was adopted and it worked very well. The key thing that had to be determined was what revision of this 37-60 we had. This one relocated the bakelite line caps to a different location. The original tone control caps were located outside and inside a bakelite block. This radio was version Run #5. The #40 condenser block was stuffed with a 0.1 mfd cap. One end was connected the ground. The other end is connected to one side of the tone pot. Condenser #41 was removed and discarded. This was a very easy mod. Thanks Mike!