From: John F. Woods (firstname.lastname@example.org)
> Best of all are the light tan cores
> (-7). They feature a plus 30 ppm tempco, although they are not as available
> as the -2 and -6 flavors.
-7 cores are white. I forget which number their light tan cores are, but
if I remember correctly, that's the core with essentially 0ppm tempco, and
permeability of 1: it's a bakelite toroid for winding VHF cores...
I buy most of my toroids from Amidon, who has 7s in stock. (Though they
had a minor bobble on my last order: they sent me 10 T44-7 cores instead
of T50-7. I called them up to arrange to send them back, and they said
just hang onto the wrong ones, they'll just send a batch of the right ones.
Unfortunately, they sent ANOTHER batch of 10 T44-7s... (Fortunately, they
have almost the same A-sub-L factor as T50s, so I figured it wasn't worth
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