The 4304BB valve by STC is a VHF transmitting triode. The filament is just visible at the bottom of the anode cavity and is a spiral around the vertical rod that holds the wire and makes the return connection. The grid and anode are seen connecting to the top of the envelope by substantial supports.

This is a lower power version of the 4304CB which has a carbon anode.

The balloon envelope is 60 mm in diameter and, excluding the B4 base pins, is 140 mm tall.

 
Pin Connections

B4	1	2	3	4	tc	tc
	-	f	f	-	g1	a

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	freq	f.max
	7.5	3.2	1000	-170	100	100 MHz	300 MHz

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 18 July 2007 {find valves by name}