The CV1055 is directly equivalent to the EBC33, and this exhibit has both names present on the metalising. The valve is a double diode triode. The design dates from the late 1930s. The literature says the device was designed for use as an AF voltage amplifier for use at the end of an IF chain where the diodes would demodulate the AM signal and rectify an AGC control voltage, and the triode would act as the first audio amplification stage.

The external screening metalisation precludes an inspection of the actual construction of the valve.

The classic envelope is 30 mm in diameter and excluding the IO base pins and central locating spigot is 84 mm tall.

References: Datasheet, ¹⁰⁴⁰, ¹⁰⁴³ & ³⁰⁰². Type CV1055 was first introduced^¶ in 1938.

 
Pin Connections

IO	1	2	3	4	5	6	7	8	tc
	m	h	a	a(d2)	a(d1)	-	h	k	g1

 
Absolute Maximum Operating Conditions^¶

Triode	Vh	Ah	Va	Vg	mAa	ra	gm
	6.3	0.2	250	-5.5	5	15k	2

Thanks to Frank Philipse for supplying the above PDF datasheet