Sensibly equivalent¶ to:
The delightful Type 717A is known as a 'little doorknob' (for the doorknob see 703A). Intended as a low-noise front-end amplifier in UHF radar receivers, the 717A achieves 4 ma/V despite its small size. Designed by Western Electric, the 717A was made in large numbers by several US manufacturers during WWII. It was a successful valve although it was soon superseded by improved (and cheaper) all-glass types.
In the John Lawrence collection are two of these valves, one is marked as a microwave triode and the other as a VHF triode.
See also VT-269 under close inspection it is clearly a pentode.
The balloon envelope is 34 mm in diameter and, excluding the IO base pins, is 37 mm tall.
References: Private Communication.
Absolute Maximum Operating Conditions¶
Updated December18, 2018. shape:balloon construction:glass.foot type:pentode age:1940.1950 base:io heater:6.3v pins:8 pin:1.s pin:2.h pin:3.k pin:4.g1 pin:5.k pin:6.g2 pin:7.h pin:8.a