Ohms on coils

[padiho]

Can somebody explain to me why sometimes ( not always ) when I make my coils, I first test the ohms before putting the centre pin back in. Usually it will show 2-2.3 which is what I like. However when I put the centre pin back in it can change to as low as 1.6. Is this normal or am I doing something wrong.

[davetherayon]

What atty padiho? Generally speaking the resistance fully assembled is most accurate, it may be that your centre pin is causing a short on part of the coil, reducing its resistance. Watch for hot spots when you do a burn test (if you do them).

[padiho]

Yes I do a burn test...if it all lights up I continue ( not sure what to look for with a hot spot?) the atti I'm using are the evod/protank ones. I buy the GS-h2 clearo from fasttech and then recoil them all.

[prr]

Could be shorting on the chimney, or when the chimney goes on the coil is moving. When I place the coil in a head I use a 1mm screwdriver as a holder to place it in the head.

[hijack]

how do you test it before the centre pin is in place?

if you are testing before the centre pin is in place then maybe the extra length of the leg is giving a higher reading. When you put the pin in it acts to shorten the leg. The resistance will be from the top of the inserted pin as that's essentially where the wire begins, not the end that you trim.

reading previous post then you mean the chimney. yes its probably touching the housing somewhere, try gripping it with tweezers and moving it so it sits in the middle more.

[padiho]

I presume they are safe to use?

[padiho]

Aug 20, 2014 18:25:25 GMT hijack said:

how do you test it before the centre pin is in place?

if you are testing before the centre pin is in place then maybe the extra length of the leg is giving a higher reading. When you put the pin in it acts to shorten the leg. The resistance will be from the top of the inserted pin as that's essentially where the wire begins, not the end that you trim.

Bit lost on this I'm afraid. I may have given the wrong idea. I make the coil, bring the legs through, put the little rubber grommet in followed by the pin...I then test to see if the coil is lighting up ok, then test the ohms...if all ok I put the big pin ( chimney? ) on and test again...that's when at times the resistance will change...so presume its something to do with the placing of the chimney?

[markm]

Its grounding out on something - possibly the chimney/pin

[davetherayon]

What atty?

[blakey]

When you test the coil before fitting you get the resistance of the entire coil plus legs, when you fit the center pin you lose the resistance from the leg that the pin traps at the point where it touches.
Also if any part of the coil leg is touching any metal part of the attie then the same will apply.
And you have to factor in that your legs will be shorter still once they've been trimmed after fitting.
If you're using a multimeter then try taking the readings from half way up the legs of the completed coil before fitting to get a better idea of the ohms you're likely to end up with.