The CV2748 (5Z4GT) was designed to supply equipment of up to 40 Watts total power, this rectifier was made by several manufacturers. This confirms it as a very popular type. The GT miniature octal type was introduced after the original metal 5Z4 of the mid 1930s, and the standard glass 5Z4G versions had become established. It illustrates the trend to smaller devices.
The anode area of this valve is much smaller than that found in the 5Z4G and so must have run hotter. The equivalent GZ30 has a larger anode surface area.
The twin anodes with four flanges around the central cathode. The pinch is present but much smaller than earlier devices.
Face view of one anode.
The wide glass tube envelope is 28 mm in diameter and excluding the IO base pins, is 72 mm tall.
Reference: Data-sheet. Type CV2748 was first introduced in 1953. See also1953 adverts.