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EL84

Sensibly equivalent to:
6BQ5 6P15 CV2975 N709
See also:
Mullard's EL84 - High Quality Audio Amplification - Mullard EL84 Advert, January, 1954 - Mullard VHF FM Radio Series Advert, June 1954 - Made for Music Advert - EL84 Distributed Loading Advert - A Small High Quality Amplifier - Transformerless Amplifiers - Audiophiles Advert - New Valve Assembly Method - Noval Based Valves for Audio Amplifiers Advert - Current Limited 0-200V Supply
    
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The EL84 output pentode was introduced by Mullard in 1954. To demonstrate its use and quality the Mullard applications lab produced an amplifier design. The now classic 5-10 high quality audio amplifier.
The performance figures given here refer to class A operation.
When used as a pair in an ultra-linear push-pull configuration with 43% distributed loading the output could reach 10 W with 0.9 % total harmonic distortion.
With ultra-linear operation the screen grids were connected to taps in the in the output transformer primary winding. The valve operating conditions so produced were intermediate between a triode and a pentode. The operation of the distributed loading was to introduce negative feedback directly within the output stage.
See also UL84 & PL84 produced for designs using AC or DC mains without a mains transformer and a series heater chain. The PL84 was used for TV frame output service.
By clicking the link from the exhibit name above, the full Mullard data-sheet can be downloaded. Warning this is a very large PDF file.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 70 mm tall.
References: Data-sheet & 1040. Type EL84 was first introduced in 1953.

 

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

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
gm
Pout
Pdiss
6.3
0.76
250
250
-7.3
48
5.5
6.7
2.2
12W
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated January 11, 2018.
shape:thin.glass.tube construction:all.glass type:pentode age:1950.1960 base:b9a heater:6.3v pins:9 pin:1.ic pin:2.g1 pin:3.k.g3 pin:4.h pin:5.h pin:6.ic pin:7.a pin:8.ic pin:9.g2
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