The S6F33 is a special quality version of the 6F33 RF pentode, the structure is open with the anode being formed by two small plates that are strapped together. The suppressor grid is closely spaced and the valve has a very short suppressor grid control curve.

The maximum anode dissipation is 3 Watts and the fine wire screen grid dissipation is up to 1.5 Watts.

The thin glass tube envelope is 18 mm in diameter, and excluding the base pins is 44 mm tall.

References: Datasheet, ¹⁰⁴⁰ & Ray Cooper. Type S6F33 was first introduced^¶ in 1961.

 
Pin Connections

B7G	1	2	3	4	5	6	7
	g1	k	h	h	a	g3,a(d)	g2

 
Absolute Maximum Operating Conditions^¶

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	gm
	6.3	0.35	300	300	-	-	-	4.0

Thanks to Frank Philipse for supplying the above PDF datasheet