The TSP4 dating from 1936 is a screened pentode for RF or VF (video frequency) amplification typically for television use. The TSP4 was one of the first valves developed for the (then) very high frequencies required for high definition television.

As was standard for such valves the maximum separation between anode and control grid circuits was achieved by taking g1 to the top cap.

The classic envelope is 42 mm in diameter and, excluding the B7 base pins, is 112 mm tall.

References: Datasheet & ¹⁰⁴³. Type TSP4 was first introduced^¶ in 1936.

 
Pin Connections

B7	1	2	3	4	5	6	7	tc
	m	a	g3	h	h	k	g2	g1

 
Absolute Maximum Operating Conditions^¶

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	gm
	4.0	1.3	200	100	-2.5	8.0	1.5	4.7

Thanks to Frank Philipse for supplying the above PDF datasheet