Posted by PakProtector [ 207.245.71.215 ] on December 23, 2005 at 22:41:40:

In Reply to: an invitation posted by PakProtector on December 18, 2005 at 17:35:57:

When I said 'zero gap' I did mean zero intentional gap. Some prelim L measurements give me cause to believe it is quite small...

Anyway, I have a few inductors designed for no DC, and either marketed for or designed as grid chokes. Some large signal, like power triode grids, and one for small signal, as for an inpt stage.

I am going to measure the impedance across the audio spectrum. With DCR, and low frequency impedance, I'll be able to calculate inductance. Unfortunately, where the core begins to get less and less efficient, the capacitance from the windings starts complicating things. With some of them, I suspect that the winding capacitance is going to raise Hell long before we get anywhere near the limits of the core.

As mentioned somewhere else, I will take a few measurements at each frequency, and varying signal to determine the effects of increased signal, and account for small changes in actual AC voltage across the coil as the impedance changes with frequency.

So now to get through Christmas so I can look more closely at some data( and of course more chokes ).
Cheers,
Douglas

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