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The EF97 is a variable μ RF and IF pentode for use in car radios. Note the very low anode voltage compared with previous generations of car radio valves that used a vibrator fed HT transformer.

The EF97 was introduced in 1959 just a few years before transistor car radios took the market. The yellow paint was used in 1969 to mark the golden anniversary of the founding of Mullard.

The screen and the coating inside the glass, The construction of the anode is just two small plates on either side of the cathode and stray electrons hitting the glass would gradually cause gas to be released from the glass. The coating stops this and thus extends the life of the valve.

The thin glass tube envelope is 17 mm in diameter, and excluding the B7G base pins is 47 mm tall.

References: Data-sheet, ¹⁰⁴⁰. Type EF97 was first introduced in 1959. See also 1959 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.