Designed for general purpose audio monitoring, removed from old communications equipment

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)
Plessey later was absorbed and evolved into BAE Systems
PLESSEY – Loudspeaker
Made in Australia
Circa production 1980’s ~ 1980’s
Model: 21B4B
Impedance ESTIMATED 8 Ohm (Voice coil DC resistance measured at 7.3 Ohm)
Power Handling capability unknown but it wouldn’t be wise to push more than 2 Watt RMS through these I feel
Frequency response is also unknown but as they were intended for communications equipment, something like 500Hz ~ 3Khz would seem likely
Cone material; Paper
Fully enclosed basket
Solder terminals (not spade type)

DIMENSIONS:
Cone: 3 Inch
90mm x 90mm x 40mm front to back
30mm diameter magnet
Magnet has a shield fitted, I cannot easily detect the magnetic field of the magnet
4x mounting holes in each corner of the frame
The holes are 70mm apart from each other (straight line) or 100mm apart diagonally

COSMETIC CONDITION:
CLEAN
Basket is clean and not corroded (pressed metal)
Paper cone is undamaged – no holes or tears!
Physical movement of the cone feels fine, smooth without “scraping” of the voice-coil/magnet gap heard
Solder terminals are clean and ready to go

I have now placed this loudspeaker face down onto very stiff cardboard and sealed within clear plastic to protect the cone primarily.