Hand Coil Wave-Winder

[Yorkie]

Those coils look first rate David, I know where to go now for IF transformer rewinds...

Lawrence.

Me too Lawrence - Ed Dinning or Mike Barker!!

Inductors have a mind of their own and often produce peculiar results.

In the Denco DRR2 coil for example, the tapped MW coil shows 30uH and 70uH when each part of the coil is separately measured, so we might reasonably expect the total inductance to be 100uH. Not a bit of it - the total is actually 170uH, the reason being that when coils are closely coupled - as is the case in this example - mutual inductance arises which affects the total inductance. If a single layer tapped coil is wound, on say a 1" diameter coil former, the total inductance will be the same as, or close to, the sum of the two parts of the coil.

I've attached the Repanco data sheet on the DRR2 coil, annotated with my findings back in Nov 2012.

I think this is one aspect of electronics where it pays to be afflicted with OCD so one can intensely focus on the task in hand to the exclusion of everything else until the mission is accomplished. I'm afraid I'm just not programmed that way - I tend to dabble in lots of things, but not properly get involved in anything - more to the ADHD end of the spectrum! Maybe that's why my eyes glaze over when I try, but repeatedly fail, to raise my game when it comes to CAD. No excuse of course - more by way of explanation. 15 minutes with a CAD programme is positively soporific - I'm nodding off and dribbling all over the keyboard.