Cam switches

Cam switches are used in many Tek instruments, particularly in 7000-series plug-ins, but also in TM500 equipment and 400-series portable scopes.

The lobes on the rotary cam encode the lookup table of which contacts should be open or closed in each rotational position of the shaft, which is typically rotated by a knob on the front panel of the instrument. A benefit of this design is low parasitics compared to traditional rotary wafer switches.

The original idea for the]is switch type is credited to Howard Vollum - see Patent 3,562,464 Cam actuated switch having movable and fixed contacts on circuit board (Vollum, Verhoff, Sprando).

Ken Holland was involved with the development of cam switches at Tek.

For cleaning, Tek recommends swiping paper soaked in isopropyl alcohol between the contacts and pads.