There are just a few places that I have found that carry it; those that do will only sell me $125.00 worth. I need just enough for a 2" diameter, 1/2" thick doughnut! The #11 has been suggested to withstand about 400 watts.

By who, and how did they arrive at that? I can't imagine a toroidal loading inductor wound on a 2" toroid that would be limited by the copper loss difference between #14 and #11 wire. I would think that core heating would dominate in either case. A quick EZNEC estimate of the RF resistance of the two sizes on 7MHz suggests that #14 wire has a RF resistance of about 40 milliohms/foot and #11 is about 28 milliohms/foot at that frequency.

Seems like you're going to peak out at Q = 200-250 for an iron powder toroid. If that's the case, an estimate I've done here suggests that if you use #14 wire, less than 10% of the resistance is wire resistance.

What I actually did was grabbed a #2 toroid for a low pass filter I'm building... it's 2.9uH, about 130 ohms at 7MHz. If we assume Q=200, that's 0.65 ohms total loss resistance. It's got about 10 turns of wire, and that's about 15 inches of wire. If my EZNEC resistance estimate for #14 is correct then the wire resistance is only 0.05 ohms, about 8% of the total resistance. If you used the #11, the wire resistance would be 0.035 ohms and about 6% of the total for this particular coil. The percentage should get better with higher reactance at least until you start to get close to stuffing the core as full as you can get in a single layer.

I'm fairly certain that you'll cook the core long before the wire heating becomes a problem if you use #14 if you have that on hand. If you're too worried about it you could sling some teflon sleeving over #12 but I feel like that will just make it heavier and hard to wind for no good reason.

73

Dan