The DB4-1 is a small oscilloscope tube with a short persistence blue phosphor and was designed for oscillography (photographs of the trace).

The tube was made with different colours and each given a separate designation: DG4-1 = green medium persistance, DP4-1 = blue and greenish-yellow for combined short and long persistance.

The gun (left) and electron lens (focus) all held in correct alignment by the ceramic rods. The Aquadag (colloidal graphite) coating obscures the deflection electrodes in the electrostatically deflected CRT.

The screen shows no blemishes and the phosphor is very even. This is clearly a tube for professional applications.

The B9G base that was introduced by Philips in 1938.

The end window envelope is 33 mm in diameter, and excluding the B9Gbase pins is  mm tall. The screen has a diameter of 42 mm.

Reference: Datasheet. Type DB4-1 was first introduced^¶ in 1953.

 
Pin Connections

B9G	1	2	3	4	5	6	7	8	9
	h,k	y1	y2	a3	x2	x1	a2	a1	h

 
Absolute Maximum Operating Conditions^¶

CRT	Vh	Ah	Va
	6.3	0.31	1000

Thanks to Frank Philipse for supplying the above PDF datasheet