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Philco 18 oscillator coil rewind - Printable Version

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Philco 18 oscillator coil rewind - jeffb - 01-29-2018

Hello all, I have an open secondary winding on my oscillator coil, item #16 in the parts list with a secondary resistance value of 3.4 ohms. I counted 16 turns of original transformer or magnet wire, which is about the size of a human hair. The smallest transformer wire I have is 33 AWG. When I restring the secondary coil with 16 turns as original, I am measuring 1.2 ohms. So, what is more important here, the resistance value (which I think they used as a measuring reference) or the inductive reactance which is how this coil is actually used? I know the number of turns affects the inductance, but I get the wrong value when checked with a vom. Thoughts?? Thanks!!

RE: Philco 18 oscillator coil rewind - Radioroslyn - 01-29-2018

Inductance trumps the resistance. The resistance is going to be different as your wire size is larger. If you don't have enough turns it won't oscillate at the low end of the band. Coil is used to couple feedback from the cathode to the grid and is not in a resonant circuit.

RE: Philco 18 oscillator coil rewind - jeffb - 01-29-2018

So should I go with my rewound coil with 16 turns measuring 1.2 ohms?? Thanks

RE: Philco 18 oscillator coil rewind - morzh - 01-29-2018

Forget ohms. Go for the turns. Also if you don't have the proper wire (often gauge 42) I recommend you buy a spool, with 30-s radios comes handy more often than I'd like to see it.
If the coil is not a part of the resonant tank the turns is the only thing that matter.
If it were, than everything would matter, turns, length of winding, thickness etc.

RE: Philco 18 oscillator coil rewind - jeffb - 01-29-2018

Thanks for the help gents!!!