This double triode is equivalent to the Mullard ECC81. The device was designed for RF use and is of the low impedance type.

We have another Brimar 12AT7 in the collection. The difference being in the cosmetic appearance.

The anode is strengthened by pressing a ridge in the broad face.

The thin glass tube envelope is 20 mm in diameter and excluding B9A base pins the length is 47 mm.

 
Pin Connections

B9A	1	2	3	4	5	6	7	8	9
	a(2)	g1(2)	k(2)	h	h	a(1)	g1(1)	k(1)	hct

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	ra	gm
	6.3	0.6	250	2.0	10.0	10,000	5.5

Thanks to Frank Philipse for supplying the above PDF datasheet

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This exhibit was last updated on 11 October 2009