How to rewind a variocoupler?

[jbivy]

I picked up a pretty trashed homebrew receiver at a pawn shop. I was able to salvage two large bakelite variocouplers, three of the five bakelite tube sockets and the binding posts. The knobs have puppy chew marks on them and while cute, theyre now junk, but not bad for 30 bucks.

Does anyone know where i can find a tutorial on how to properly rewind these variocouplers?

Theres a few designs ive seen that i would like to try out, but they call for variocouplers. I assume i use the length of wire as called for in the right gauge and just wrap each part?

[Reece]

Sounds right. Shoot us a pic.

[jbivy]

No pics as of yet, but its labeled elkay on several parts and from what i can see, the two variometers look identical to these from 1925. Well, at least to both the 4 and 5 tube models in the pics.

http://www.radiomuseum.org/r/langbei...lector_4s.html

EDIT

when it rains, it pours variocouplers. I just picked up a nice bakelite kellog on epay, with a few loose windings of course.

Is there a trick to rebuilding these?

[Reece]

Is there any wire left on them? Is it a matter of rewinding what's there or is the wire gone? Most of those would have been wound with cotton or silk covered wire which is pretty hard to find these days. I think I'd try to find as many pictures on the web of different ones and get an idea that way. There are probably "shadows" on the coil forms showing the approximate gauge of the wire and the width of the entire windings. Take the units apart and wind away using a suitable gauge modern enameled wire. Not original, but...they're no longer original anyway.

[jbivy]

Would the cloth covered Litz wire work rather than enameled?

One just has "loose" wiring, like it used to be glued to the coil but now has some play. One is a true rats nest with perhaps half the wiring in a ball around it, with one that looks fair, but shows continuity and doesnt rub when turned.

[Reece]

Sure, Litz wire would be fine, better than what was there. Modern Litz you just solder, the hot solder melts away the invidual enamel on the strands. However, if you can salvage the original wire and make it look good, that's what I'd do. You can take one end loose and try to tighten the whole thing up as a unit, then reattach the wire. If that doesn't work, you'd have to unwind it and to keep it from kinking, you can unwind it loosely into a cardboard box on the floor, then rewind from the box by hand. Have some strips of duct tape at hand to anchor it temporarily if you have to stop in between. Old timers used to shellac finished coils. You could also use spray lacquer.