LF: 3C90 Al value?

[G0MRF@aol.com]

Hello Group.

After a 4 month wait I've received a batch of 58mm cores claiming to be 3C90, but according to the catalogue they have the wrong colour code. These are white (pos 3C11) not blue/white for 3C90.

The way to confirm is to calculate the Al value and compare to the data on 3C90 3C85 3C11 etc materials. Unfortunately 3C90 is not listed in my old data book.

I've measured the inductance of a 21 turn winding at 1.43mH. 
Using  L = Al x N squared, this suggests an Al value of 3249.

Is this a good figure for 3C90?  It does seem far too low for 3C11 (5000+)
Perhaps they've changed the colour code again?

73

David    G0MRF