The PCF80 is from the dawn of the era of VHF Band III television in the UK. The valve is a triode pentode, with separate cathodes, designed to function as a mixer and oscillator in the tuner front end.

The gap in the anode at right angles to the electron flow allows a view of the wire suppressor grid. The copper supports seen above the top mica are for the control grid.

The triode on the left has copper grid supports. Both anodes are made with a shaped section stitched to a flat sheet. The inner surface is left bright on both anodes.

The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 49 mm tall.

References: Datasheet & ¹⁰⁴⁰ Type PCF80 was first introduced^¶ in 1953.

 
Pin Connections

B9A	1	2	3	4	5	6	7	8	9
	a(t)	g1	g2	h	h	a	k,s,g3	k(t)	g1(t)

 
Absolute Maximum Operating Conditions^¶

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	9	0.3	170	170	-5.5	5.2	1.5	0.87M	2.1

Triode	Va	Vg	mAa
	100	-2	14

Thanks to Frank Philipse for supplying the above PDF datasheet

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