Recycling a post….Are Toroids getting you all wound up…..

Since the fall is coming and kit building will be on the rise I wanted to recycle this post from last year...
When I decided a few years ago to venture into a new area of amateur radio.....kit building. I did  some research on the internet to see what I was up against. Having never built a kit and not really having any electronics background I did not want to get in over my head. So it was a simple kit to begin with but at the same time something I would use and not just become a home to dust bunnies. I decided on the Elecraft KX1 kit as it would I hoped turn out to be a functioning radio. One I could put to use in portable operation again this was another area of amateur radio I had yet to discover. So I practiced my soldering, put together some tools and one thing that kept waking me up at nights....(not really) was the TOROID WINDING!!!!!!! There is lots on the internet on how to go about winding a toroid. With the KX1 kit I found myself trying the different methods and at times  having to rewind some toroids many times. A few weekends ago during slow times in the ARCI contest I decided to do some toroid winding for my on going KPA100 100 watt option for my K2 Elecraft radio.
 I added Soft rubber to jaws of the vise
Chopstick method

I just want to share some of the ideas I tried during my trial and error periods of toroid winding. Also the process I go through from start to finish. As with most any kit I have worked with you are given a recommended length of wire to cut and I have found at least with the Elecraft kits the total wire given is always more than enough to wind all the toroids. Now comes the fun part the winding, there was three methods I tried. The first was putting the toroid core in a vise and winding the wire through the core. I found this to be somewhat awkward for me, some may find it works for them but I was opening and
closing the vise and moving the core around more than winding the toroid. Using the vise seemed to take a very long time. But having said that if your hand is not steady the vise is a very good alternative. The vise did  great to just hold the toroid for the later step of stripping the leads...more about that later. The next idea that came across my path was the use of a chopstick, I included a picture of what I am taking about and we all know how a picture is worth a thousand words.
Using the chopstick I was able to form the turns of the wire nicely around the inside of the toroid. At the same time space the turns out so the toroid looked very balanced. I used this method with building my KX1 and as I wound each turn I inserted the chopstick and inspected the toroid. As I progressed to my next kit (Elecraft K2) I used the chopsticks for eating and not winding toroids. As it turned out this too was a method that just seem to complicate the winding process. As I gained confidence  winding  toroids I just put on my magnifying head set and wound them by hand!!! This proved to be the road for me in regards to gettin r done with the infamous toroid. See the link at the bottom of post to see how winding a toroid by hand is done.  Once the toroid is wound you have to remove the coating of insulation on the wire. In this regard I read of sanding it off, using a lighter or flame of some type to bun it off or a hot solder blob. I tried the sandpaper method but I found it to be a little hard on the toroid windings and sometimes the sandpaper got to close to the turns of wire and removed some insulation there as well. I gave the open flame a go but found I was just heating up the wire and really did not have any control over removing the insulation and heat required to remove the insulation.
Tinning leads
The method I settled on and works great for me is the solder blob method.  I use a type of mini vise with alligator clips on the ends to hold the toroid in place I then change the solder tip to a larger one.  The soldering station is turned up to about 800 degrees Fahrenheit the hot tip is placed on the lead to be tinned and solder is applied to tip and wire until a small amount of smoke begins to form. At that point the solder and soldering iron is moved slowly along the toroid wire adding solder as I go along. At this point I also want to mention that I also use a solder fume extractor when ever I am soldering and for sure when tinning the toroid leads. There are many on the market for a reasonable price.

                                            SOME TIPS I FOUND HELPFUL
1. I always recount the number of turns just before the last turn is done. I find sometimes more turns are needed or I lost count and I have the correct turns already.
2. Just before placing the toroid into the circuit board one lead is cut shorter than the other. I find this makes placement of the leads into the board holes easier. 
3.  I ALWAYS use an ohm meter to check that my tinning job worked and the insulation is stripped.
4. Once the toroid is soldered in place before cutting the leads flush with the  board I double check again with the ohm meter for continuity.

With practice I found the toroid winding can go smooth and it can be pleasurable as well.  
1 hour and 20 minutes of toroid wind.
                                     Links  that deal with toroid winding

The vise method   Once you are at the web page click on the upper left link "Toroid winding"


Mike Weir, VE9KK, is a regular contributor to and writes from New Brunswick, Canada. Contact him at [email protected].

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