The delightful Type 713A is electrically identical to the 717A. The only difference is the 713A has a screen connection on the base.
The design of both types earned them the nickname of 'little doorknob' (for the doorknob see 703A).
Intended as a low-noise front-end amplifier in UHF radar receivers, the 713A achieves 4 ma/V despite its small size. Designed by Western Electric, the 713A was made in large numbers by several US manufacturers during WWII including Tung-Sol as here.
It was a successful valve although it was soon superseded by improved (and cheaper) all-glass types.
The lettering on the dome identifies the originator as Western Electric and the outsourced maker as Tung-Sol.
The very small pentode section sitting above the glass foot.
Looking at the bottom mica, the cathode tube is rectangular and the inner grids are close wound. The anode is notched at the sides.
The balloon envelope is 33 mm in diameter and, excluding the IO base pins, is 32 mm tall.
