Re: TT-42 saga; NSTs, tuning, steadiness, etc.
Hi John, all,
In reply to some queries on my coil:
> Original Poster: FutureT-at-aol-dot-com
> Hello coilers,
> I installed a 15/30 NST into the TC which gave nice 43" sparks with
> a breakout bump on the 13" toroid, and nice multiple streamers about
> 40" long with no breakout bump. It turns out that the tuning was not
> just right before which was contributing to the unsteady operation with
> the PT's. I noticed that with smooth toroids....if you tap outwards too
> much, the operation will be erratic. This is because the coil is then
> tuned for longest sparks if they're formed. But they can't easily form
> because the coil is mistuned before they break out. But if a break
> out bump is installed, then the coil can be tuned (tapped) outwards
> more, and still run OK. IWO, using a smooth toroid, you can tap
> outwards more if there's a bump on the toroid. Maybe something
> like this was happening in Malcolm's coil when it had intermittent
> breakout problems with the large topload. (Malcolm, did you try
> tapping inward at that time?) I wound up tapping at 15 turns instead
> of 15.5 which was the old tune point with the PT. I may have had
> to tune at 14.5 turns without the bump, I'd have to check my notes.
Tapping wasn't really on because there were so few turns in the
primary and its inductance was rather low. A tap wire run around
the outside would have simply added/cancelled part of the tapped
inductance depending on which way it was run. The topload wasn't
particularly smooth either - it was just large with a fairly large
average ROC. It now lives on the coil which can hit five feet on
occasions. In the end, it seemed that the primary chokes were
causing some kind of problem.
Thanks for the ongoing reporting of your results with different coils
and transformers. I am listening with great interest. I would like to
say that I am going to do this and that this year but perhaps its
better if I don't get ahead of that which I actually get done.