On May 8, 9:50 pm, "Joel Kolstad"
wrote:
....
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.

An automatic tuner I worked on a long time ago had motor-driven
variable inductors only slightly larger than that. I guess it handled
about 200 watts. The design wasn't roller, but slider; it tuned very
fast for a mechanical system. There were one or two motor-driven
vacuum variables in there too.

Cheers,
Tom