And a parallel coil works the same way as two single coils in parallel as far as ohms go.
It can be checked with a digital multimeter. Put the positive (red) lead on the center post and the negative (black) lead on the bottom of the deck. Don't waste your money on one of the little black box style ohm checkers.
Why? Lots of folks use these with great success, including me. I also have a multimeter which I don't bother using since the "little black box" seems to be working just fine and is waaaaaaay more convenient.
So, I just check it without firing it? I'm sure I can find a decently cheap multimeter at walmart or something.
They work fine unless you want to get into really low sub-ohms. I don't trust their accuracy to be honest with you.
And... the black box style would be useless for the OP, he's using a hybrid RDA. No 510 threading.
Kinda wish I had the money for a new deck so I didn't have to use this one, since it can't be checked on an ohm meter.
I believe he used something the same size as 5/8th. It's not very big, but not very small either.
ALL decks, tanks, etc.... can be checked with an ohm meter or multimeter. take a picture of this mystery device side, top and bottom... and more than one of us can tell you how and were to put the contacts of a multi-meter to it.