Hopefully my crazy idea of disks to create beyond cutoff waveguides is useable for the band of frequencies of "interest". Otherwise, you might have to "hotFOOT" it by switching the resistors with FETs (bad pun somewhere there), using the switch to control the FETs.
here's an idea drill a small hole (~1mm) through the panel near the shaft hole shuch that the hole will be hidden behind the knob but is not covered by the nut or flange, through this hole put a pice of spring wire bend the underside end at 90 degress and do the same at the top side but twist it so the the spring touches opposite sides of the switch, eg it presses on the left side of the flage below the panel and the right side of the shaft above the panel
Plan
_______________ / \\ / ......... \\ / ............. \\ / ... _______ ... \\ / ... / \\ ... \\ / ...#############... \\ / ...###############... \\ / ...#################...@ \\ + / ...#################..@ \\ + \\ ...#################.@.. / + \\ ...#################@.. / + \\ ...###############@.. / + \\ ...#############@.. / + \\ ...###########@.. / + \\ ............@. / + \\ ..........@ / + \\ @ / + \\_________@_____/ + @ + @ +++++++++(@)@ ++++ spring behind panel (@) hole @@@ spring above panel _ / \\ nut \\_/ _ / \\ ### shaft ... ... bolt/bushing ............ ............ ......@@@@@@@
-- The space between the shaft and the bushing is tiny, so with a light enough lubricant capillary action would draw it in along with the powdered silver.
Yep, that's my spin on John's idea, with an ASCII telling.
I think it elegant, affordable, and very robust, but agree that Grayhill's the preferred route.
Cheers, James Arthur
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.