Dang! Look what the cat dragged out ... these pots were still in the original trays and I am pretty sure these dated from my early days in manufacturing, way back in the 1970's ~ 1980's
Historical, absolutely! Useful, well ahhhhhh .... I hope someone can find a special project to use these!
PLESSEY was a UK electronics design and manufacture company, often involved in scientific and defence projects. In Australia the Plessey Telecommunications division manufactured in Sydney and were involved in defence and civil contracts, including AUSSAT (Australia's FIRST very own commercial communications satellite back in 1985) I am not sure if Plessey manufactured pots here in Australia though.
Plessey later was absorbed and evolved into BAE Systems (Defence & Aerospace industries)
PLESSEY - Potentiometer
Made in Australia (possibly)
Circa production 1970's ~ 1980's
Model: No type number indicated
Value: 2x 100K
Taper: Linear
Phenolic resin wafers
Stamped into one side of each potentiometer is:
100K LIN
100K LIN (Upside down)
NOTHING ELSE is stamped into the body - not even PLESSEY. I only know these were Plessey because they were stored in the original, Plessey supplied, "pot trays" (see the photograph)
The upside stamping caused me to check the taper directions but after testing I have found BOTH tapers change resistance in the same direction
Both pots vary resistance in unison, as one increases in value so does the other - not a reverse taper pot
Tolerance is unknown but based on batch measurements, 20% is a pretty good estimate
Diecast metal body with
Cream D shape plastic shaft
PCB wire legs - NOT round wire but rectangular (see below)
DIMENSIONS:
BODY: 16mm x 16mm x 14.35mm Height
Metal nut thread is 7mm length and accepts a standard nut/locking washer (Black) which are both supplied
Required mounting hole 9.9mm diameter
Cream plastic D shape shaft is 22.5mm Length
PCB or connecting legs are orientated horizontal to the potentiometer body
PCB legs measure 4mm Length x 1mm Wide x .22mm Thick (Tinned but not sure about the base metal, in some light I can see Yellow reflections which may mean that Brass has been used for the base metal and then tinned.
It was a LONG time ago but I think we used these with "point to point" wiring, no PCB at all.
TESTING:
I undertook batch testing of a few pots to get an idea of their characteristics ....
All tracks (assumed to be carbon based) were within 20% of the indicated value. I did notice some differences between the two tracks on each pot, for example one pot measured 107K track and the other track on the same pot measured 118K
Changes in resistance (measured at the wiper) was smooth and linear, both pot resistances changing in unison.
COSMETIC CONDITION:
NEW Old Stock
CLEAN
NO damage to the diecast metal body (looks to be Zinc)
NO damage to the Brown phenolic resin wafer (probably impregnated with cotton paper) used on each pot for the track.
Solder terminations (legs) are clean and have barely any oxidisation (dullness)
