The CT-199 was specified for many uses as the data sheet shows. The bias and anode voltage for various uses are given. The operating parameters are close to the classic RCA 199.
This exhibit came in a box marked British Base but for the UK market the standard B4 base was used. This base does not match our other CT-199. The pins here are twice as long and placed differently. They do match the De Forest DV-2 in position and length and thus are the early American UV base. The brass base shell is 34 mm in diameter. It is required to be that size to fit the bayonet valve holder.
The short base pins and locating pip on the base indicate a bayonet type base.
The base pins.
The wide glass tube envelope is 26 mm in diameter, and excluding the UV base pins is 77 mm tall.
References: Data-sheet & 1043. Type CT-199 was first introduced in 1925. See also1925 adverts.
