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 and SU2150A shows the Cossor saddle style anode. However, this exhibit is different and internally looks much more like the M-OV or Mullard versions.
The SU2150 was made for a higher anode voltage but smaller maximum current.
In the early 1930s top caps had wide Bakelite skirts and screw caps. By the mid 1930s the top hat top cap had replaced the earlier style. This exhibit is hybrid and one naturally thinks that this dates to that transition period. Look more closely and the glass has etched on it the Type designation of CV1290 that must date to 1941 or later.
The electrode assembly and glass rod supports fixed into the pinch is typical of M-OV production. SeeCV1120.
The cylindrical anode with the cathode offset within. The twin rods are there to hold to top of the cathode rigid.
A closer view of the top of the oxide coated cathode.
The base of the cathode with the insulated heater passing into it.
The classic envelope is 49 mm in diameter and, excluding the B4 base pins, is 123 mm tall.