This is a HOW-TO from a newbie to a newbie, so all you pro's out there bear this in mind :) | ||
Primary coil construction I guess the first thing I had to decide was what shape and form should the fixed base take. One idea that appealed to me was to use a round breadboard, but since I dint posses one and was reluctant to go and buy one, I had to think again. This time in the garage, so much junk in here I must be able to find something, and sure enough there it was in all its grandeur |
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The secondary former was the outer sleeve of the bit I'm holding and it could slide up and down on small ridges. So turning it so the top contacts the board was the intended way of fixing. Before fixing I need to make the former for the primary, seeing I had some makralon left over this was my first choice. I cut 6 of them at a size of 3"x3" to start with then decide to mark the top at a angle, so I measure 1" from the base at one end and intersect the opposite end/top, this gives a nice slope. Having made sure the edges are smooth and square I tape them all together. Next I use a bit of ally (from the garage) and cut to the same size as the others I mark along the slope 12 holes on a 0.2" pitch, then drill each hole 0.125". This is then used as a jig to drill the makrolon, so taping it to my bundle I commence drilling.. walla, formers made. | ||
Next step is to mark the position on the base for the 6 formers, to be at 60deg. uhho, no protractor... h'mm.. Do have a compass though :) So I draw a 3" diameter circle from my center hole, then by trial and error I adjust the compass to give me 6 equally spaced positions on the circle edge. Didn't take to long and now I have my 60deg markers :) Grabbing my former I proceed to drill a small hole in the base, insert nylon screw and penny washer and fasten this down to the base. For added support I use my trusty araldite around the base/former and a thick coat of varnish inside to seal it. Next using the araldite again I place a small amount on the base of each former and fix them down on my 60deg markers with the shallow end pointing inwards and at a distance of approx., 0.2" from the secondary former edge. Although the araldite is a 5min strain, it normally takes 24hrs to cure fully, so time for a break, bbl :) | ||
Day2: Next task is to feed 12 turns of my 1.5mm wire through the holes in the 6 formers. I found the easiest way was to unwind a suitable length from the bobbin and feed firstly through the outside hole on one former, then the next etc. until I had one turn. By using forefinger and thumb on each hand gently push/pull the wire through each vacant hole. Must admit the last too turns where reluctant to thread, but being stubborn I got there, remembering to leave sufficient tails at each end. | ||
One job left to do, the safety ring. Thinks time (in the garage). Unable to find any heavy gauge wire my eye turns to the disused freeze, it died a while back when the compressor sprung a leak. Poking around in the back I notice some copper tube about 0.2" diameter and with my faithful wire cutters I snip this away and unwind it from the larger tube. After straightening it and quick rub down with sandpaper it looked like new. Now for something to support it. Remembering my former was 3" at the outside edge I looked for something that I could cut down to 4" to use. Sure enough in the bird cages were some wooden and plastic perches. The wooden was rounded .5" dowel and the plastic were oval, but underneath the plastic ones they was a groove running the full length which looked a suitable size to fit the mackrolon edge. So plastic it is then. Cutting them down to 4" was rather easy and drilling a suitable sized hole for the copper pipe was a piece of cake. carefully applying araldite to the opposite end to the hole and also in the grove, I put them in place on the vertical edge of each former, such that the holes are parallel to the primary turns. Another 24hr wait :) | ||
Last job is to carefully feed the copper pipe through each of the holes in the perches I made yesterday, was a bit fiddly, (left long tails again), but useful as the next time I make a primary I will mark out small slots. Still its all done now. One primary completed :) Ooops neally forget, that end of the copper pipe is cut off so as to leave appox., .5" space from the start position, ie we dont want a complete turn do we :). Job done. | ||
A point worth noting, its best not to use enamel covered wire, right job getting it of those small turns, next time I'll got for tinned copper or small bore copper pipe, just a thought :) | ||
BellaDonna |