The 6F26 is a VHF varible-mu pentode where the stage gain is controlled by the negative bias applied to the control grid. At the time this design was developed television receivers operated on Band I at about 50 MHz and from 1955 also on Band III at around 175 MHz. The EF183, released in the 1960s, overtook its performance.

When Band Iv and Band V UHF television entered service in the early to mid 1960's the front end required specialised triodes to operate at 400 - 850 MHz.

The reverse side of the circular anode and the made in England by a BVA member.

The compound pins with the red section having the same expansion co-efficient as the hard glass used for the base.

The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 59 mm tall.

Reference: Datasheet. Type 6F26 was first introduced^¶ in 1960.

 
Pin Connections

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

 
Absolute Maximum Operating Conditions^¶

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	6.3	0.3	250	100	-2.0	10.0	2.5	0.5M	6.0

Thanks to Frank Philipse for supplying the above PDF datasheet