31-03-2017, 04:33 AM
(This post was last modified: 31-03-2017, 04:35 AM by Diabolical Artificer.)
Winding a toroid is easier than winding a conventional tfmr in some way's but is tedious and hard work. The htr winding's were straight forward, big thick copper is easy to work, you can really tug hard on it to get the wngs tight. The only tricky wng was the thin gauge used for the bias wng.To get 18.9v @ 10 turn's for 5.35v doesn't take long. The HT winding was tricky, 10 turn's = 5.3v, 1 turn is 8" long so it was very long. You can't leave the copper on the bobbin it has to be put on a long winder bobbin. So I ran out the wire down the garden and put a bit of masking tape every 10 ft, I did this 3 1/2 times, up and down the garden cursing rose bushes and snaggling wire added a bit for luck and cut and wound the result on a bobbin, then did it again as I split the HT wng into two.
I then wound out the first bit of wire, got a drill on a variac and started winding the two together by doing 10 ft at a time to get a bifilar wire. Of coarse as you know, turn your back on wire or cable and it starts tangling, getting in knot's, diving into rose bushes, picking up bit's of grass that sort of thing. A few times it got kinks which I had to carefully straighten to avoid damaging the enamel insulation and causing a week point. It took ages, two day's to wing the HT, but I ended up with two 175v's smack on. I miscalculated the voltage drop, when rectified and loaded it was at about 435v, so added another winding at the end and brought out taps at the join. Gives me some wiggle room. It was isolated using Kafton tape.
Those ceramic standoff's are nice Nik. Mine were covered in muck and rodent pee but cleaned up nice. The wisdom is on point to point wiring that the joint should be physically good before soldering. The Tek wafer's hold the wire, component's etc in with solder only, but I figured Tek know what they were doing. BTW, I've heard that Tek used special solder with silver in it and that each scope came with a small reel of the stuff. But I've also heard this is rubbish. I'll use normal 40/60 and see how I get on.
Andy.
I then wound out the first bit of wire, got a drill on a variac and started winding the two together by doing 10 ft at a time to get a bifilar wire. Of coarse as you know, turn your back on wire or cable and it starts tangling, getting in knot's, diving into rose bushes, picking up bit's of grass that sort of thing. A few times it got kinks which I had to carefully straighten to avoid damaging the enamel insulation and causing a week point. It took ages, two day's to wing the HT, but I ended up with two 175v's smack on. I miscalculated the voltage drop, when rectified and loaded it was at about 435v, so added another winding at the end and brought out taps at the join. Gives me some wiggle room. It was isolated using Kafton tape.
Those ceramic standoff's are nice Nik. Mine were covered in muck and rodent pee but cleaned up nice. The wisdom is on point to point wiring that the joint should be physically good before soldering. The Tek wafer's hold the wire, component's etc in with solder only, but I figured Tek know what they were doing. BTW, I've heard that Tek used special solder with silver in it and that each scope came with a small reel of the stuff. But I've also heard this is rubbish. I'll use normal 40/60 and see how I get on.
Andy.
