Premium quality Spectrol panel mount potentiometer
Ex Broadcast equipment, UK manufactured

Spectrol Reliance was the UK arm of Spectrol Electronics, USA. Like so many other premium component manufacturers, Spectrol was acquired by Vishay in 2000 – Spectrol products can still be sourced but under the Vishay name.

SPECTROL RELIANCE
Square Mould Panel Potentiometer
Body (excluding thread/shaft) 12mm x 12mm x 12mm
Completely sealed
Marketed by RS Electronics (UK)
Type: not sure, there is no indication on the pot body but this looks very similar to the 148-149 Series from Vishay-Spectrol
BODY STAMP:
(RS Logo)
RES 500K
UK 9xxx (four digit number that varies with each pot, I believe this is a manufacturing date code – all number sequences begin with 93, 94 or 95 and this fits in with the equipment period of manufacture – mid 1990’s)
At the “end” of the body is the SPECTROL Logo within an oval circle stamped into the plastic
Single turn 265 degrees
500K Clockwise Linear taper
Long life – rated at 50,000 rotations
Conductive plastic OR Cermet element (unable to determine which)
PCB solder pins
1/4″ panel mount, thread with nut (supplied)
SHORT 1/4″ shaft (all round – NO flat spot) 5mm length (cut by the equipment manufacturer) and NO slot at the end of the shaft (not suitable for screwdriver adjustment)
A standard knob is unlikely to be suitable for use with this shaft, collet knobs would be the best choice.

These are ex equipment “pulls” but I have actually tested EVERY SINGLE POT! Just to be sure everything is fine. In their previous life (rack equipment which rarely had the settings altered, so the pot has actually seen very little real time rotation over the years)