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G-51

Sensibly equivalent to:
35 51
See also:
Majestic G-51 Box
    
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The G-51 (or Type 51) is a variable-μ RF tetrode and was made in America. The 2.5 Volt heater was the USA standard for AC valves until the 6.3 Volt standard emerged in the mid 1930's.
An article in the July 1931 edition of Radio News in America compares the 'old' straight Type 24 with the 'new' Vari-μ Type 51. The full edition can be found here.
For cathode bias the cathode resistor should be 330Ω.
The screen grid connects to a disc on the top ov the valve and that intern connects to the outer mesh. The anode cylinder can be seen inside the mesh screen.
The oxide coated cathode is in the centre with a circular control around it, this connects to the top cap. The close wound screen grid can be seen just inside the top metal disc.
The balloon envelope is 44 mm in diameter, and excluding the UY base pins is 110 mm tall.
Reference: 1043. Type G-51 was first introduced in 1936.

 

Pin Connections
UY
1
2
3
4
5
tc
h
a
g2
k
h
g1

 

Absolute Maximum Operating Conditions
Tetrode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
2.5
1.75
250
90
-3.0
6.5
2.5
0.4M
1.05
Updated March 28, 2019.
shape:balloon construction:pinch type:tetrode age:1930.1940 base:uy heater:2.5v pins:4 pin:1.h pin:2.a pin:3.g2 pin:4.k pin:5.h pin:tc.g1
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