Winding CoilsThere was a time in my life when I had considerable fear of winding coils. I have dubbed this Helixaphobia. Most beginning builders suffer from this fear but there is no need to. I have developed methods which overcome the problems people normally experience when winding coils.
Maybe you just don't want to wind coils. I won't hold that against you. If you would rather buy them ready made try Antique Electronics Supply. After the site comes up look in the frame on the left and scroll down to, and select "Radio Parts & Restoration". In the tree menu that comes up just to the right of where you were looking click on "Coils & Coil Forms". Scroll down to the 9th item. Items 9, 10, and 11, are the antenna, oscillator, and RF, coils for an AM Radio. Below are the data and pictures of the coils.
You need three items to wind the coils for the projects given here. They are;
The magnet wire used to come from Radio Shack. In keeping with their policy of figuring out what the best products are and discontinuing them they no longer have it.
Fine gauge wire is available from many sources including Antique Electronic Supply. To help you figure out what to order here are the wire sizes.
It has come to my attention that short lengths of PVC pipe are available from home improvement stores. A plastic form would make a much mor durable coil than cardboard. You might want to look into it.
Wire Color Wire Gauge Copper Colored 22 Green 26 Red 30
Next you need a 2 inch mailing tube. These are available from your local post office, Mail Boxes Etcetera, Container World, and many discount and variety stores. To repeat exactly what I have done you need a 2 inch not a 3 inch, not a 2 - 1/2 inch not a 1 - 1/2 inch. The length will be more than you are likely to use.
The third thing is Double Stick Scotch Tape. Once again the local discount or variety store should have it.
You will eventually need three coils; 1) an antenna coil, 2) an RF interstage coil, and 3) an oscillator coil. The antenna coil, #1, is used in the crystal set and all of the one-tube radio circuits. The RF interstage coil is needed for the two-tube TRF circuit and the deluxe superheterodyne radio. The oscillator coil is used in any of the superheterodyne circuits. The initial posting of this page may not include all three but as they are needed instructions for their construction will appear here. The instructions for each coil are written to stand alone so as you work your way through winding any one coil you won't have to refer back to the instructions for any of the other coils.
Keep reading on this page for the antenna coil.
RF Interstage Coil
The oscillator coil.
This coil can be used in the crystal set as well as all of the one-tube radio circuits. It has three separate windings and in some of the circuits only two will be used but that's no problem.
Here are the steps for winding the antenna coil.
DON'T WIND THE COIL BY HOLDING THE FORM STILL
AND MOVING YOUR HAND AROUND AND AROUND THE
COIL FORM. When you do this every turn puts a twist in the wire.
After a while the wire will start to kink and then get into a hopeless
tangle. Roll the cylinder (mailing tube) around in your hand like
the take up spool on a real to real tape recorder. (Rotate the coil
form [mailing tube] around its axis.)
This page last updated November 20, 2005.