RoGeorge: Yes, I did actually make a 3 turn coil for my soldering gun as you suggest, made from 4mm copper tubing like the 1 turn coil, and this gave a current of 110A, so '330A' for all three turns - I measured these using a current transformer clamp which I know to be accurate - so along with the 200A for the single turn coil, high current tests (AC only) were:- 110A, 200A, '330A'. These measured on the Ut210E gave: 110A, 175A, '250A'. So you can see the meter does seem to read low above about 150A, as shown by El Coyote in this thread. (bear in mind that I've hacked the EEPROM in mine to raise the 100A limit to 300A. Actually it was set to 600A when I did these tests)
Below is my solder gun with the two coils made from 4mm tubing. Also my modified mains transformer with
exposed poles as a degausser.
![](https://www.eevblog.com/forum/testgear/a-look-at-the-uni-t-ut210e/?action=dlattach;attach=389474;image)
I agree that the lower gap in the jaws looks a bit bigger than the upper one - this is to allow clearance for the jaws to open I think - joeqsmith posted pictures of the jaws dismantled earlier in this thread, (post #346 page 14)
and it looks like the jaw gap is set by the plastic jaw pivot mouldings - not adjustable without re-building that pivot I suspect ? Is the pivot in your meter badly
assembled/formed so that there is much too big a gap maybe ? If I squeeze the lower part of the jaws together in mine,
I can only move them less than 0.5mm further together. Just an idea.
And as the plastic pivot wears, the gap will only get bigger I suspect, pushed apart by the spring
Have a close look at the upper jaw gap - I cut away a bit of flash with a sharp knife and got a slightly better fit...
Your meter does seem to have a fairly large DC offset even after you have degaussed though - are you clamping all 3 turns of your blue coil to degauss ? I have good degaussing results using either my modified transformer, or the soldering gun + 3 turn coil - I can get more or less degaussing with both methods depending on exactly how I do it
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
My DC offset comes down to within about +or- 20mA usually.
If you can't get any further reduction in offset by degaussing, you may be into pot adjustments inside - have a look for joeqsmith's video about this - it isn't easy though, and I'm not certain I've got mine right now, however there IS an offset adjustment pot -if I can find that joeqsmith video/post again I'll link to it here. Here it is-
https://www.eevblog.com/forum/testgear/a-look-at-the-uni-t-ut210e/msg1106210/#msg1106210Cheers, Dave