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CV3998

Sensibly equivalent to:
5A/170K 6688 E180F
See also:
Nuvistor Valves
    
Extras ▼

 

The CV3998 is a high-slope RF beam tetrode primarily intended for use in wideband amplifiers in telephone carrier systems, radar equipment and measuring equipment. The CV specification shows that the Government requirement was for the GPO telephone system. The prototypes were the 5A/170K from STC and the E180F from Mullard.
This very small size helps to reduce inter electrode capacitance and thereby raises the maximum usable frequency at which the device can operate.
The lower part of the heater wire is coiled. Within the insulation the coil will be close wound. The STC logo and the commercial Type 5A/170K is also visible.
The anode looks indented but is in fact flat.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 33 mm tall.
References: Data-sheet & 1040. Type CV3998 was first introduced in 1957.

 

Pin Connections
B9A
1
2
3
4
5
6
7
8
9
k
g1
k
h
h
k
a
g3,s
g2

 

Absolute Maximum Operating Conditions
Beam Tetrode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.3
190
160
-1
13
3.3
35K
16.5
PDF scanned from an original document held by the museum
Updated May 14, 2021.
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