Roy Lewallen wrote:

Michael A. Terrell wrote:

Fair Radio used to have some in their catalog, and they were used in
all of the old Delco (and some other brands) car radios of the '60s and
'70s.

Just about all the radios I've seen with mechanical pushbuttons for
station presets used permeability tuned inductors


All of the american made radios were, but some cheap imports weren't.

-- the pushbuttons
each just positioned a ferrite core to a preset depth in a coil. It
wouldn't be difficult to construct one, unless you're mechanically
declined like I am.

Roy Lewallen, W7EL


I once told one of the Vice president of marketing at United Video
Cablevision that he was mechanically declined and my boss freaked out.
;-) The VP yelled at him and told him to shut up because it was true,
and he was happy that whenever he had to launch a new channel in the
Cincinnati system that everything was set up and ready for him when he
arrived.


Of course, you could make them as individually tuned coils with a
stepper motor or servo per coil.

--
?

Michael A. Terrell
Central Florida