[Amps] TMC amp toroid tank

[Tom W8JI]

> Anyone have any experience with toroid tank coils? Is 
> efficiency normally
> poor on the higher bands?

I'd never use a torrid in a wide frequency range tank 
circuit. If the toroid behaved perfectly as in theory it 
would not work at all over wide frequency ranges.
This is because in a normal pick up and hold tank switching 
system, without significant flux leakage in the toroid the Q 
would go to zero along with the inductance on higher bands. 
The only way around that problem is to not short unused 
turns, and then you would get into a switch arcing problem 
on higher bands!

In practice most lower mu physically large toroids will 
barely have enough flux leakage to work in circuits 
requiring low Q when turns are shorted. I suspect that is 
the reason for your low efficiency.

73 Tom