This exhibit is GE acorn valve type 958A. The few details found suggest that this is a triode with a 1.25 Volt 0.1 Amp filament. We thought all acorn valves had 6.3 Volt heaters so we may be looking at another 958.

The acorn envelope is 14 mm in diameter, and excluding the pins is 32 mm tall.

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	ra	gm
	1.25	0.1	135	-7.5	3.0	10,000	1.2

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 06 January 2008 {find valves by name}