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CV2901

Sensibly equivalent to:
6267 CV4085 EF86
See also:
Mullard's EF86 - A Low Cost Amplifier
    
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The CV2901 is the UK service designation for the low noise audio amplifier pentode EF86 (Mullard) or Z729 (M-OV). The EF86 design is anti-microphonic. In use it is recommended that it is fitted into a vibration resistant base formed by isolated the base from the metal skirt by a synthetic rubber mount.
This exhibit is an import and carries the term Foreign in place of the maker.
See also CV4086 for the flying lead version.
Looking along the grid axis through the gap in the outer screen. The latter is made from perforated and expanded sheet. The three grids are visible and the method of securing the wire to the supports is clear to see. This was known as the notch and peen system where a cutting wheel opened a depression in the support that the winding would sit within. The metal forced up by the notch knife wheel was then pressed down over the wire by the peening roller.
The thin glass tube envelope is 20 mm in diameter and excluding the B9A base pins, is 47 mm tall.
References: Data-sheet & 1040. Type CV2901 was first introduced in 1954.

 

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

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vg
mAa
ra
gm
6.3
0.2
250
-5
4
2.5M
2
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated June 10, 2021.
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