Hi Joel,

On Tue, 08 May 2007 21:50:06 -0700, Joel Kolstad wrote:

I've been thinking of getting some roller inductors to play with next
time I visit a hamfest, and it occurred to me that a generic roller
inductor doesn't have a linear change in inductance with roller
position... does it? E.g., at the half-way point you should get 1/4 the
total inductance, right?

Right, unless it's wound linear inductance. Those can be found as surplus
from test equipment. The ones found surplus in receiver's are usually
linear frequency, rather than linear inductance. They are visibly quite
different.


P.S. -- They never made small (say, size of an old Kodak film
canister)-sized roller inductors meant for QRP work, did they? Most
seem to be sized for hundreds if not thousands of watts.

They exist. I could barely give a dual one away on Ebay last year. Dual
QRP roller too! Finally someone grabbed it for $5.

Cheers,

Gregg