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AC/SG

Sensibly equivalent to:
8A1 AC/S2Pen CV1164 CV2822 HP4101C MS/Pen MSP4 SP4 SPT4A
See also:
Mazda 1929 Valve Range Advert - Mazda AC Valves advert - Mazda Brand advert - Some Important British Valves
    
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The Mazda AC/SG is and AC heated Screen Grid or tetrode amplifier for RF use. Our other AC/SG has a different construction with the original box screen grid.
The heater is the then UK standard of 4.0 Volts at 1.0 Amp. The original valves in 1929 had a metal top cap as can be seen in the advert. Also the advert shows an envelope with a cylindrical section at the base, just like this valve. The original S625 was made cylindrical as it was intended to be mounted with the screen mesh aligning with an external metal box that seperated the input from the anode circuit. The shape of the envelope indicates that the missing top cap may have been of the metal screw top type.
See also the metalised AC/SG.
The anode with cylindrical anode cavity. Note the glass bead holding the other electrodes and the cylindrical screen at the bottom of the image.
The anode connection passes through the glass bead.
The wire that is seen second from the right in the glass bead connects to the top of the heater. The helical close wound screen grid is clearly visible.
The balloon envelope is 51 mm in diameter, and excluding the B5 base pins is 116 mm tall.
References: 1040 & 1043. Type AC/SG was first introduced in 1929.

 

Pin Connections
B5
1
2
3
4
5
tc
g2
g1
h
h
k
a

 

Absolute Maximum Operating Conditions
Tetrode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
4.0
1.0
200
60
-1.5
4.5
0.8
0.9M
1.9
Updated November 21, 2016.
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