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Editorial Consultant: Rod Burman

A Brief History of Valves

A Brief History of Valves

A Brief History of the Transistor

A Brief History of the Transistor


Image of 3C24 VT204 PHILIPS VALVE, 1938

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3C24 VT204 PHILIPS VALVE, 1938

Philips Transmitter VHF Triode of 1938.

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A0607

Image of QQV07-50 MULLARD VALVE, 1964

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QQV07-50 MULLARD VALVE, 1964

Mullard QQV07-50 Double Beam Tetrode of 1964.

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A0705

Image of MULLARD  '0.20' TRIODE, 1921

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MULLARD '0.20' TRIODE, 1921

Mullard '0.20' Triode of 1921. Transmitting triode with an Anode dissipation of 20 Watts.

Maker known then as the Mullard Wireless Service Company Ltd

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A0645

Image of ACT6, CV1222, VALVE ON BASE, 1920's

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ACT6, CV1222, VALVE ON BASE, 1920's

1.5Kv, 75 Watts air cooled Triode for transmitting use.

ACT stands for Air Cooled Transmitter. Shown on a special Bayonet 4 pin base of the American 'Jumbo' type and has an Oxide Coated filament.

Specially designed to work at wavelengths as short as 4 metres. In practice, the valve was suitable as as amplifier or oscillator down to 10 metres at full rating and down to 4 metres at reduced HT voltage.

The anode was provided with a fluted heat sink to aid dissipation of the heat, but the valve would work with natural convection. The anode cooler was of cast aluminium, the outer surface being finished for radiation cooling, this was shrunk on to the anode by preheating and then applying it to the anode.

Marconi used it as an oscillator in some of their transmitters.

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A0585

Image of CAT 9 MOV, 1937

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CAT 9 MOV, 1937

CAT9 18KW 50 Mghz High Power Triode for Transmitting, air and water cooled.
750mm 2Ft 6inches long. CAT= Cooled Anode Triode
A water cooled transmitter triode. The filament connections are at the top, the grid at the side (RHS in the picture), and the anode is the copper lower half of the valve. The ring between the copper and glass is to allow a blast of air to cool the seal. The anode corona shield incorporates a connector to allow air blasting off the seal for cooling.
Used by the BBC sometimes in pairs.

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A0584

Image of VT 218 EIMAC VALVE, 1937

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VT 218 EIMAC VALVE, 1937

Eimac VT218 100 MHz Triode of 1937.

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A0656

Image of RK28A RAYTHEON, 1937

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RK28A RAYTHEON, 1937

Transmitting Pentode of 1937 on paxolin chassis mounting base.

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A0588

Image of LEWIS 35T VALVE, 1936

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LEWIS 35T VALVE, 1936

VHF Transmitter Triode of 1936.

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A0605

Image of CV 1994 ACT9 MOV, 1936

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CV 1994 ACT9 MOV, 1936

Act9 or CV1994 Filament 16.3volts Triode 10,000 Volts 8 Amps Transmitter of 1936. Act stands for Air Cooled Transmitter. Used in the Marconi SWB10 Transmitters the mobile Army Command transmitter, Golden Arrow and Green Archer used by the RAF. The valve was capable of continuous power dissipation of over 1Kw in operation down to 20 metres and at reduced HT at wavelengths down to 3.5 meters.

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A0590

Image of PX25 BALLOON, 1937

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PX25 BALLOON, 1937

Used in the Modulation chain of the Marconi SWB Transmitter, see Item A0862.
The PX25 was a Thoriated Tungsten directly heated filament, for 25 Watt audio outputs.
Much loved by modern HI-FI aficionado's.

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A0592

Image of 4E27/257B HEINTZ AND KAUFMAN VALVE, 1938

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4E27/257B HEINTZ AND KAUFMAN VALVE, 1938

Heintz and Kaufmann 4E27 Transmitting Pentode of 1938.

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A0658

Image of QV08-100 MULLARD VALVE, 1960

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QV08-100 MULLARD VALVE, 1960

Mullard QV08-100 100 Watt Transmitting Tetrode of 1960.

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A0703

Image of QY5-3000A MULLARD VALVE, 1964

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QY5-3000A MULLARD VALVE, 1964

Mullard QY5-3000A 3KWatt Transmitting Tetrode of 1964.

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A0654

Image of HEINTZ AND KAUFMAN GAMMATRON VALVE, 1930's

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HEINTZ AND KAUFMAN GAMMATRON VALVE, 1930's

VHF Transmitter Triode of the late 1930's.
Heintz and Kaufman use Gammatron as their trade mark.

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A0606


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