The 2D21 thyratron is, as usual, a gas filled valve. This example is of tetrode construction and was designed for relay or grid-controlled rectifier applications.

When a certain critical anode current flows the ionisation of the gas begins an avalanche discharge that overrides the grid control and leads to saturation current flow. The anode current can then only be extinguished by reducing the anode volts below the ionisation threshold.

The gm value in a normal hard valve is replaced by the control ratio parameter. In this valve the ratio is 250. At saturation the valve voltage drop is 8 Volts.

The thin glass tube envelope is 17 mm in diameter and, excluding the B7G base pins, is 44 mm tall.

 
Pin Connections

B7G	1	2	3	4	5	6	7
	g1	k	h	h	g2	a	g2

 
Absolute Maximum Operating Conditions

Thyratron	Vh	Ah	Va	mAa
	6.3	0.6	650	500

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 09 June 2007 {find valves by name}