Original poster: "Herwig Roscher by way of Terry Fritz <twftesla-at-qwest-dot-net>" <herwig.roscher-at-gmx.de> John, Bart and Gary, Thank you very much for dispelling my fears. Yes, it is a normal SG coil. And i can lower the secondary bottom several inches below the primary plane as I have got enough space. I will download the mentioned programs and see, what they will "tell" me :-) Cheers, Herwig