Thank you, Wally. This going to be handy in the long run, if we can remember to look in this thread. Perhaps we should add a page to the Wiki for the L2 coil specifications.
What do you think sufficient permeability would be?
From TSCI's document,which I linked to above, they sell threaded cores with permeabilities of 6, 7, 8, 8.5, 10, and 20. They list "recommended frequency ranges" of 40 - 250 MHz, 35 - 135 MHz, 10 - 100 MHz, 1 - 60 MHz, 100KHz - 25 MHz, and 50 KHz - 5 MHz respectively.
They have part numbers for the 1/4-28 X .75" threaded core at all six of those permeabilities. Do you think that someone replacing a disintegrated L2 core would need both a .75" core and a .25" core, or would the .75" core be sufficient? Or needs experimenting to tell for certain?
I've had an email reply from the Customer Service Rep. at TSCI, so if we can pick out a permeability, I can give her a specific part number that I'm interested in.
They have plain rods in .245"D X 1"L and .245"D X 1.25"L, but the threaded cores only go to .75" alas. They also mention that teflon coating is available on the threaded rods, but from what you wrote, I think we want to avoid that, yes?