The 6P25 is an audio output valve and the electrodes are obscured by the coating on the glass. The 6P25 is pin compatible with the KT61 etc.

The identification is etched into the dome of the envelope. The dome was left dirty as it was considered that cleaning would have damaged some of the lettering. The rest of the glass was thoroughly cleaned.

The classic envelope is 43 mm in diameter and, excluding the IO base pins, is 102 mm tall.

 
Pin Connections

IO	1	2	3	4	5	6	7	8
	m	h	a	g2	g1	-	h	k

 
Absolute Maximum Operating Conditions

Beam Tetrode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm	rk	rl	Pout	D
	6.3	1.1	250	250	-8.5	40.0	8.0	40,000	8.8	180	5,000	4.5	7%

This exhibit was last updated on 10 March 2008