Mains transformer 300-0-300V @100mA 6.3V@1A 6.3V@2A CT (Mullard 5-10 Mono or 3-3 Stereo)


300V – 0 – 300V 100mA

6.3V @ 2A Centre tapped

6.3V @ 1A

Incorporated copper screen for electrostatic noise reduction, and safety.

Designed and tested to European standards.

Earn up to 137 Points.

5% discount on 2 or more


A superb quality mains transformer for any valve project. Originally designed to power a Mullard 5-10 Mono amplifier. It will happily power a stereo Mullard 3-3 amplifier alone, without the pre-amp.
Proudly made in the United Kingdom


European primary voltages, 220V, 230V, 240V and 250V.
US primary dual 120V.


HT winding 300V – 0 – 300V at 100mA DC
Heater winding 6.3V at 2A centre tapped.
Rectifier winding 6.3V at 1A


High quality Grain Orientated M6 0.35mm.
Hand laminated for the best stacking factor, and accuracy.

Winding wire

Double coated Grade 2 enamelled copper wire.
Wound using CNC winders for highly accurate wire placement and turns count.

Electrostatic Screen

Solid copper sheet providing the best RF screening possible between primary and secondaries.

Connecting wire

High quality PVC 600V
Primary and HT : 24AWG UL1015
Secondary LT : 20 AWG UL1015




Built and tested to safety standard BS EN 61558-1 2005

Additional information

Weight 2.3 kg
Mounting type

Frame, Stand up, Drop through

Primary Voltage

European, US


Here are dimensional diagrams for this transformer.
Please refer to the relevant key below for the dimensions.


Shroud With Feet Drawing Key

Label Description Dimension (mm)
A Width 79
B Height 98
C Depth 82
D Mounting depth 57
E Mounting width 64
F Hole width 5

Drop through Drawing Key

Label Description Dimension (mm)
A Width 79
B Length 95
C Height 66
D Cutout width 48
E Cutout length 64
F Fixing length 79
G Fixing width 64
H Mounting hole diameter 4.1

Frame Drawing Key

Label Description Dimension (mm)
A Width 98
B Height 83
C Depth 66
D Mounting height 70
E Mounting width 64
F Mounting depth 54
G Overall depth 70
H Mounting hole width 5


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