Cossor designed and made EHT rectifiers such as the SU2150A for use in CRT power supplies. Because the Cossor works tended to employ skilled glass-blowers rather than just factory girls, and because they were designing for a very limited market, the Cossor EHT rectifiers were designed to be hand made. Although naive looking they were electrically robust and entirely successful in their intended application.
The SU2150 was made for a higher anode voltage but smaller maximum current.
The plastic top cap and screw connection places this exhibit in the early 1930s as does the style of paper identification. Later production SU2150As adopted the standard metal top cap connection.
The saddle anode is connected to the top cap and is supported on glass pillars. The cathode assembly is always at least 6 mm distant from the anode, and is a horizontal rod. The maximum reservoir capacitor is 0.25 µF, and the minimum series resistance is 10,000 Ω.
The balloon envelope is 50 mm in diameter and, excluding the B4 base pins, is 126 mm tall.