Quite difficult to find these days, and to be frank, most servicemen wouldn't need them! But if you like to dabble in the wonderful world of vintage portable radios or similar portable equipment then this biscuit knob may be just what you are looking for ...
I call these biscuit knobs, just to be clear what type of knob this is, here is a snapshot inside a portable transistor radio showing one of these fitted.
In brief, this is a very thin round knob with a serrated edge (to provide friction between the users finger and the knob) with no markings (numbers etc) on the knob at all. It fits onto a tiny shaft, usually a potentiometer, with the underside having a very small rectangular socket that the shaft will fit into, finally it is held securely in place with a tiny (and I mean tiny!) threaded screw.
So here we go with the detailed description ...
UNKNOWN MANUFACTURER - Biscuit Knob
Country of origin is most likely Japan (it came from a Japanese 'trannie')
Material: Plastic
Colour: White
Special indented rectangular receptacle on the underside, into which the control shaft is supposed to fit - a central threaded hole would be in the shaft so that the supplied screw can hold everything in place securely.
DIMENSIONS:
31.9mm outer diameter (1.25") x 2.7mm thick
The rectangular slot measures 4mm x 2.5mm
COSMETIC CONDITION:
USED
Clean (very)
NO physical damage
NO discolouration to the top or underside
Packed into a sealed clear plastic packet, along with the tiny screw
