Hi guys,
I took three goes to get mine correctly wound and installed. I have no excuses other than age!?
However here are the lessons I learned along the way since I wound my first one back in the mid nineties for my NORCAL 40a
My normal practice when winding toroids is to ?:-?
A. Cut the wire to length, there are quite a few on line calculators to help you with this such as?
B. Take a look at the PCB to see which way to wind it. There are two ways, clockwise and anti-clockwise, the aim is to use the way which matches the holes on the PCB.?
C. Wind the required number of turns making sure you leave a tail at the start and end so you can feed the wire through the holes on the PCB prior to soldering.?
D. Double check the number of turns. If your eyes are as bad as mine you might wish to take a take a picture enlarge it on the screen and count that way. Correct any errors.?
E. Tin the wire tails. Some people use the solder blob method, others scrape the insulation from the wire then tin, others burn it off. I tend to scrape a little off then use the solder blob method. Holding the toroid still while you do this can be difficult. I use a tapered chopstick mounted vertically in a small vice for this. The hole of the toroid neatly fits on the stick which holds it still enough to work on. My hands shake quite a bit at times so I find this trick useful, I learned it from an American ham whose callsign I have forgotten.?
F. When soldering to the PCB use the smallest amount of solder needed to make the joint. Most hams use way too much solder. Mostly that doesn¡¯t matter but with toroids it¡¯s often the case that you have to change the number of turns which means you have desolder the joint. The more solder you have on the joint the more you have to remove. One trick I use is to use a stainless steel sewing pin with a glass top, if you have made balsa wood model aircraft you probably have some. Heat the joint pull the wire out put the pin in the hole and twist it. The solder won¡¯t stick to the pin and you end up with a hole which will take the wire.?
G. When you wind a toroidal transformer it does make sense to use different colours of wires for each winding. I bought a load from a craft fair. As a beginner it made things a lot less confusing for me.?
Now in the case of Hans¡¯s instructions I thought to follow them because I have learned a lot from him in the past. The first two times I wound the transformer I made the loops too short. On the third attempt I got it right. However I found it easier to untwist the loop before I cut them and to thread the ends through the inside holes before the outer one. I expected some problems soldering the wires because I couldn¡¯t pre tin them in my usual method. However what helped was the liberal application of some flux from a Chemtronics dispensing pen. This seemed to help the solder ¡°melt¡± the insulation on the wire cleanly, quickly and with less heat than usual. It¡¯s a technique I will use again. May be I won¡¯t have to use my pre tinning technique if this works.?
I¡¯m sorry if this is too long for you old players but the OCX is being built by a lot of newcomers to construction and may be this will be helpful.?
Regards?
Steve G0XAR
