This is the classic RF Power tetrode valve for VHF and low UHF applications. The base is a special because it has to incorporate the air system, a matching ceramic chimney was made for the base, and the control grid was connected to the central metal spigot.

We have the co-axial version in the museum as well as similar types. The anode to outer ring is filled with folded ribbon for a large surface area and this is clearly visible. All external metalwork is silver plated.

We have an example of the glass based 4X150A in the museum, this is almost identical but has a lower power rating.

Thanks to Graham, G3XTZ for providing details of the correct heater voltage.

The co-axial envelope is 41 mm in diameter and, excluding the B8F base pins, is 45 mm tall.

 
Pin Connections

B8F	1	2	3	4	5	6	7	8	tc
	g2	k	h	k	-	k	h	k	a

 
Absolute Maximum Operating Conditions

Tetrode	Vh	Ah	Va	Vs	mAa	Pout	freq	f.max
	26.5	-	1500	300	250	235	175	500

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 03 December 2007 {find valves by name}