Diy inductors in general as well as induction meter use.

So I have been attempting a extended pultec inductor myself and have just a few questions about this process as this will be the first time that I have ever wound an inductor.  I've noticed that after I get the whole toroid wound and all values almost exact when I epoxy resin the whole shebang all my values go askew.  I have also noticed that I get different results depending upon the day/temperature/whatever when I check the values on this thing.  This could partially be due to having a cheapo induction meter.  I have noticed that with larger values on the core the longer I leave the meter attached over time the lower the inductance reading I get, should I be going with the first value I get when attaching the meter?  I was also wondering just how close the values have to be to work with the Pultec?

Here a nice site on inductor DIY...

http://www.diygallery.de/DIYsites/index.html

If you want to know the exact values you should have an expensive & calibrated meter.
However, you can still use your meter to match pairs for a stereo unit.
Maybe send an inductor you measured before to someone with a good meter and let him/her meassure your inductor.
You can than calibrate your meter accordingly...

Also, most inductors I've seen have a 20% tolerance...

While a cheapo meter may not be 100% accurate in absolute values, I doubt the variance you're seeing is due to the meter. My bet is that the core gap is changing as you apply the epoxy, which will change the value. Have you thought of trying the cores with the screw that enable you to tweak the gap?


Justin

btw - to prove the above point, I've seen coil winders apply a trick: if you don't have cores with the screw, and the value is slightly out, you can gently grind the cores together to make the gap smaller. Voila! The AL factor changes and the inductance follows accordingly.

toroidal cores? what material?

here is a god L thread--think it mentions variations due to temp, etc.
http://www.groupdiy.com/index.php?topic=14093.0