Clockman, thats a good looking result thus far... making me look bad
Had a 1 year old 5kw PJ turn up today with a noisy transformer. It turned out to be one of the totem driver transistors causing the problem... it went short to ground, so the h bridge was unbalanced to say the least..... first failure I know of from inverter duty only. It struggled to get to 240v in that state, and made a horrid noise.... all good now.... a 3 cent transistor can make a difference. Can't see why it went... will delve further to see if I can find anything else to report.
I think the 118 is a fair target, wish I could be more accurate.... but it sounds like you have more core than me or very close, so 118 should be fine. It won't hurt to do more if you want to get the magnetizing currents even lower. The further you are from saturation, the lower the currents required.
At some point, it gets fairly linear, and not worth going further as the copper loss rises, but up near the top of the curve, the results from lowering the current by increasing the turns, is very very handy. ( it is the extra turns on the primary to cater for the more turns on the secondary that matter really).
Beware, you may have to cut down your favourite bobbin to smaller size as your hole gets smaller. There is no crime in having to join as you go.... (twist and solder).
Handy looking little torroids you have there to play with.... wonder how many turns/volt they would be....instead of volts per turn.
Thats true Mary..... but....
But i found with 2mm wire, it is much much easier to use the bobbin as clockman has done. If you push it through the correct way around, as it unwinds, it places the wire hard against the core wall, if you use a flat bobbin with thick wire, it just becomes a nightmare to get it to sit correctly... and if you use reclaimed wire (me), it is so tensile as to be an absolutely painful experience......... unless you use the round bobbin.
This gets more problematic as you get to less hole size, but the flat bobbin offers no help at all in keeping it both taught, and straight and tidy.
For winding your 1800v using spider web comparatively, the flat bobbin way will do fine, but I would still use a round bobbin if i could, as I have found it so easy to remain tidy and tight.
But if your hole is too small, then the flat bobbin is the only answer.... sadly.