The 1637 is an uncommon version of the EL32 that was very common in a number of guises. RCA made the 1637 during WWII for the UK.
The 1637 is an octal based audio output pentode. Mullard say of the EL32 design that it is a 200 mA heater valve for use in AC/DC sets or for use in car radios. The values given are for single ended use, in push pull a pair can deliver 7 W.
The copper control grid support rods have heat radiating fins top and bottom.
The anode has a cylindrical cavity and four flanges set at right angles for greater radiating effect.
Made in USA.
The wide glass tube envelope is 29 mm in diameter and, excluding the IO base pins, is 90 mm tall.
