The 5B/255M beam tetrode was designed for transmitter use in the HF and low VHF parts of the spectrum. The design has the same rating as the 807. The 5B/255M has a sister valve, the 5B/254M, that is a miniature enveloped version of the 807 complete with anode top cap.

In addition to RF power, the valves were designated for service as audio power amplifiers. Here the valve was to operate in class AB1 and a pair would deliver 15 Watts at 3% total distortion.

The wide glass tube envelope is 29 mm in diameter and, excluding the B8B base pins, is 79  mm tall.

 
Pin Connections

B8B	1	2	3	4	5	6	7	8
	h	a	g2	k-bp	g1	g1	k-bp	h

 
Absolute Maximum Operating Conditions

Beam Tetrode

Vh

Ah

Va

Vs

Vg

mAa

mAs

mAg

Pdriv

Pout

Pdiss

freq

6.3

0.9

600

250

-45

100

8

4

0.3W

40W

25W

60

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 02 July 2007 {find valves by name}