Anyone with experience with the Jantzen P-Core inductors?

[hershey]

In need to unwind a 1.8 mH P-Core inductor to reach a target of approximately 1.6 mH and I don't have any way of measuring inductance. I'm hoping that someone has experience working with these particular inductors and can tell me aproximately how many turns I should unwind.

Also, once I've unwound them if I liked how it sounded before I made the change is it possible to rewind the inductor and have it achieve similar result as it did before unwinding? I know that sounds a little cheap but I'm a poor married student with a new baby and no loose cash to buy extra inductors if I screw up the ones that I currently have. Thanks for your help.

Here's a little teaser on the project I'm working on, just to make the post more interesting:

413

414

[wg_ski]

If the flux is confined to the core (pretty good assumption if there's iron involved) the inductance is proportional to the square of the # of turns. To figure out how many you need, you'll need to count how many there were to start with and that may require careful unwinding.

Instead of just cutting off the "excess", just scrape off some of the enamel and put on a tap and finish winding the rest back on. Then you can hook it up either way in seconds.