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Chuck asks:
>What is the issue(s) with using only toroids for a tank circuit?<
One problem you can have is being able to get thick enough wire on to the core.
At 1500 watts, you can have a lot of current in that coil, so you need a hefty
conductor. You also need a large enough core that you can ensure it doesn't get
anywhere near saturation, becasue that's real bad news. You also need to
evaluate the unloaded Q of the inductor, and the losses in the core, because
you will get core heating, and you need to make sure that the watts dissipated
in the core aren't enough to cause heating problems. When cores get too hot
(past their Curie point) the permeability drops to zero, although with dust
iron, I'd expect it to literally catch fire first when the organic binder gets
going. When a toroid iron dust core catches fire, it's quite spectacular (been
there, done that, never again!)
Down at the 100 watt level, it's very practical, but up at 1500 watts, it's a
bit more complicated, and I'd suggest you need to do a number of calculations
before jumping in. The biggest problem I see is the total unwieldyness of
winding really thick wire on to the core. Incidentally, you'll be stuck with
using dust iron, and you need polytetrafluorethylene (trade mark name is
Teflon) insulation on the wire, or in suitably thick 'cheeks' on the toroid. At
the end of the day, at 1500 watts, I think that the air wound coil is rather
more practical, although I'm aware that amps have been done with toroids.
Hope this helps
73
Peter G3RZP
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