Sensibly equivalent¶ to:
Here we have a DF33 made by Ever Ready. Ever Ready valves of the 1930's were supplied by Mullard. Usually they carried an Ever Ready Type designation but here the Philips/Mullard code is used directly.
The DF33 is a variable μ RF pentode for dry battery operation. Mullard designate this device for service at both RF and IF in broadcast receivers. It was part of the 'red series' of valves that were first introduced in 1938.
The relatively large size of the valve suggests that it was not designed for battery portable sets but for fixed operation. The filaments had to have the lowest possible consumption due to the cost of the dry batteries.
The reverse of the glass is covered in plain red metallising paint.
The wide glass tube envelope is 30 mm in diameter, and excluding the IO base pins is 86 mm tall.
References: Data-sheet, 3002 & 1040. Type DF33 was first introduced in 1939. See also 1939 adverts.
Absolute Maximum Operating Conditions¶
Updated January 05, 2022.