Hello everyone, I decided a few weeks ago to tackle the open band #2 oscillator coil on my other Philco 37-116 chassis. I wasn't looking forward to taking apart the RF unit but it had to be done. I tested the oscillator coil previously and it had continuity from 1-2, 2-3, 3-4 but open from 4-5 which meant the primary windings were good and secondary was bad. I remember when Phorum member Rfeenstra restoring a 37-116 chassis he had back in 2019 and he showed how he rewound his open band #2 oscillator coil--I looked at how he did it and rewound my secondary winding on my coil. I used #36 AWG copper enameled wire and rewound the secondary using 12 turns of wire--- I counted 11 turns but added an extra turn just in case I didn't have enough range on the adjustment trimmers. I recoated the windings with wax and installed the coil and reinstalled the RF deck in the chassis. I then retested the chassis holding my breath as I haven't rewound an oscillator coil successfully before and wasn't sure it would work. I was very surprised not only did it work on band 2 but I was able to align it at both ends of the band and no oscillator dropouts anywhere on the band--CHU on 3.330 MHz, WWV on 2.5 MHz and my local station on 1.6 MHz (1600 KHz) were on the correct spots on the dial. I thought I would let everyone know just in case they have a band 2 oscillator that they need to rewind. Ken
Great job Ken!
I'll mention in passing that I believe that the rf decks in the 37-670, 675, 116, and the 690 are very similar if not the same from what I've seen. And from what I've read band 2 is the most likely coil to fail.
We'll have to get Nathan to put this in the coil rewinding section of the library.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
I wish I took more pictures of me rewinding the secondary coil— I removed it without removing the oscillator section off the RF deck—too many connections to unsolder-I took pictures of where all 5 coil wires went and used small needle nose pliers to carefully remove the wires off the band switch/ trimmer terminal lugs as I unsoldered them—when I unwound the secondary there was some green corrosion on it but I cleaned any traces off the coil form and checked the primary and there was no sign of corrosion(yet). Rfeenstra’s close-up pictures of how he rewound the coil helped me successfully rewind the coil—so far band 2 is holding alignment and no frequency drift. Ken
