Uhmm....
OK, the 2 mm kanthal doesn't sound correct. 2 mm is 12 gauge wire. Unless you're talking about ribbon and not wire. Most would use 28 to 36 gauge wire. The 2 mm sounds like the wick diameter. Particularly if you wound a 3.8 ohm coil for a Vivi Nova.
Here's the condensed version of ohms: The thicker the wire, the lower the ohms for any given length of the same metal. Also the shorter the wire, the lower the ohms.
Then we have "shorts" which bypass the wire at some point, and reduce the ohms.
Pics of your build may help, but here's some hints:
More wraps = more ohms.
If you have a multimeter...put the leads on the wire and measure the ohms. Cut it a little long. If you don't have a multimeter, consider getting one as they are real handy for checking all sorts of stuff.
Oxidize the wire 1st. Run it quickly through a flame. It's called annealing, and it makes it easier to work with as well as adding a thin coating of oxides/carbon on the wire.
Try not to have the coils touching each other. There are some builds (micro-coils) that do this, but for your 1st builds, I'd suggest not right now...particularly if you got .7 ohms and were shooting for much higher.
You'll soon learn how much wire you need to make a 2.5 ohm coil, particularly if you use the meter to measure it. Otherwise you're left with counting "wraps" and that's not very accurate at all. Although it may be repeatable for YOU if you become consistent with your particular wraps.
Try to keep the coils loose. Don't choke the wicking material. Some people wrap the coils on a machine screw or drill bit and then pull the wick through. This works better for cotton wicks IMO than for silica. For silica, I just loosely wrap it.
I also use a magnifying glass and a "helping hands" stand. Google it. It's commonly used for electronics.
Fingernail trimmers are pretty handy if you don't have small wire cutters.
Wash hands before doing anything and avoid getting finger oil/grime on stuff as much as you can. Keep it all clean and stored in bags.
I suggest rinsing everything off and doing a drying-burn to dry the wick AFTER you test the ohms. Don't put the coil on a mech without checking for shorts 1st.
The Vivi Nova's outside shell is the ground connection. The center post is the positive connection. Watch it...it's tight in there. But if I were to err on the side of caution, I'd want the ground side to be the side that "shorts" against the coil, not the center post side of the coil. Of course, you really don't want either side to short.
If you rinse the wicking, make sure not to inhale the first few puffs until it begins wicking
juice. And make sure you wet it well with juice.
Some people boil the wicking material before use to remove any ...stuff...that may be on it.
Is the rsst using mesh wick? You have to oxidize the mesh real well, and anneal the coil too. Shorts will reduce ohms.
As always, it's a good idea to keep up on ECF's safety precautions...particularly when building your own coils.
