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Philco 38-12 oscillator coil - Printable Version

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Philco 38-12 oscillator coil - Tubeglow20 - 08-26-2022

    Hello, I know that the topic of the Philco 38-12 oscillator coil has been discussed many times on the phorum,  but I have a question I wanted to ask before I mess something up. On my oscillator coil, the primary, terminals 1 & 2, show a resistance of 2.9 ohms and the schematic shows 2.5 ohms which I know is close enough. The secondary,  terminals 3 & 4, show 1.5 ohms and the schematic shows 3.5 ohms. The secondary winding looks good for the most part, but there is some green corrosion on the winding. Would this have an effect on the DC resistance and make it drop? Will the coil work as is, or will I need to rewind the secondary?

RE: Philco 38-12 oscillator coil - Radioroslyn - 08-27-2022

I have a suggestion. Just tack it in and give it a try. Then you'll know for sure.

RE: Philco 38-12 oscillator coil - Ron Ramirez - 08-27-2022

Agree with Terry, but in the condition it is in, it will have to be rewound sooner or later - probably sooner.

I strongly suggest you bake it in an old toaster oven at 200 degrees for 30 minutes first, then be sure you wind the new wire in the same direction as the original, and with the same number of turns as the original - using the same or very similar size wire (looks like it may be 36 gauge).

Another person on here was looking for someone with a 38-12 so he could identify the terminals on the oscillator coil - specifically, which lug connected to what on the coil form itself. Perhaps you can help answer his questions.

https://philcoradio.com/phorum/showthread.php?tid=23706

Thanks.

RE: Philco 38-12 oscillator coil - Radioroslyn - 08-27-2022

Or https://www.tubesandmore.com/products/coil-miniature-adjustable-coil-70-oscillator Someone wrote a review that it worked fine in their 38-12.

RE: Philco 38-12 oscillator coil - Ron Ramirez - 08-27-2022

That may be so, but the OP in the other thread really wanted to know the pinout of the original 38-12 oscillator coil - as it relates to the actual wires on the coil itself. In other words, what coil wire went to which pin. Only an original 38-12 oscillator coil will reveal that information.

RE: Philco 38-12 oscillator coil - Radioroslyn - 08-28-2022

My take a way was that it has green dots and would it work? Or would the other winding have to be rewound? Think reading must be like a Rorschsch inkblot.

RE: Philco 38-12 oscillator coil - RodB - 08-28-2022

So it's a good thing to have a collective interpretation.

RE: Philco 38-12 oscillator coil - Tubeglow20 - 09-25-2022

    Ok, here's an update on my oscillator coil from my 38-12 radio I'm working on. As stated in my previous post, the DC resistance on the secondary showed 1.5 ohms. I carefully unwound the secondary winding and the wire was not broken anywhere; got 1 continuous piece of wire. After taking several measurements,  I concluded that the wire was 34 gauge. Also looked at the original wire and the new 34 gauge wire under a jewelers loupe and they looked identical. Carefully replaced the insulating "plastic"??? piece between the windings and wound 25 turns of the 34 guage wire on the form. After winding the wire DC resistance measured at 1.6 ohms; almost like the original. Took many pictures and drew a diagram of the coil and which way to wind the wire. I want to suggest that maybe the schematic is wrong where it shows the resistance at 3.5 ohms; IDK. After completing the coil winding, I coated the winding in a slight coating of beeswax to make it look original. I think it came out looking pretty good considering I wound it by hand. I'll post updates when I eventually power up the radio.

RE: Philco 38-12 oscillator coil - morzh - 09-25-2022

I see some green there. I think thhis is where the problem is.
Oh...was.