I read in sci.electronics.design that Bill Turner
wrote (in ) about 'Winding
coils', on Sun, 7 Dec 2003:
Making a plate choke which covers all frequencies from 160
through 10 meters (including the WARC bands) with sufficient inductance
but without self-resonances in any ham band is difficult to the point of
being nearly impossible. Many amplifier designers give up trying to
design such a choke and simply switch part of the inductance in or out
of the circuit depending on which band is selected.

This is a 1920s problem. Just as you parallel capacitors of different
type, electrolytic, metallized foil and ceramic, to get a wideband
component, so you put inductors of different construction in series to
get a wide band component. You can wind them all on a bit of wax-
impregnated dowel if you like. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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