Editorial Consultant: Rod Burman

WESTERN ELECTRIC 1st COMERCIAL POINT CONTACT TRANSISTORS, 1950's

Germanium Point Contact Transistor marked 1698 3.52, first production type. The 3.52, marking is different on some, this possibly refers to the date of manufacture i.e. March 1952. In original packing.
Standard Telephones and Cables (STC) was born out of the UK branch of Western Electric USA.
For Synthetic Germanium See Item A1431.

Nortel Collection

A1422

FIRST 1st UK POINT CONTACT TRANSISTOR LS736 BY STC (CRYSTAL TRIODE) AND 1st JUNCTION TYPE, 1950's

First UK production Point Contact Germanium Transistor LS736 and Data sheet. Called a Crystal Triode. First UK Junction Transistor LS828 made by STC, and 3X301N and LS837 which are later versions.

These Transistors came from STC's laboratory at Ilminster in Somerset.A label found inside this box written by the original keeper, Mr Henry Wolfson, at STC read:- 'The first point contact transistor marketed by STC', 'LS828 the first Junction transistor', '3X301n & LS873 later versions'.

For Synthetic Germanium See Item A1431.

Nortel Collection

• Detailed view of LS736 Transistor
  
• Detailed view of LS828 Transistor
  

A1427

LS737 STC POINT CONTACT TRANSISTORS IN ORIGINAL BOX , 1950's

Successor to the First UK Point Contact transistor developed in the UK by STC at Ilminster in Somerset the LS737 was a Higher current gain version of the LS736. Item A1427 These Transistors came from STC's laboratory at Ilminster in Somerset.
A label found inside this box written by the original keeper, Mr Henry Wolfson, at STC read:- 'The first point contact transistor marketed by STC', 'LS828 the first Junction transistor', '3X301n & LS873 later versions'. These other items can be seen under A1427.
For Synthetic Germanium See Item A1431.

Nortel Collection

A1429

THREE MICROSCOPE SLIDES OF TRANSISTORS STRUCTURE , 1950's

Microscope slide showing the internal parts of a Junction Transistor. From the Laboratory of STC at Ilminster.
For Synthetic Germanium See Item A1431.

Nortel Collection

• Magnified View of Transistor's Strucure
  

A1430

TRANSISTOR PROTOTYPE PACKAGING STC , 1950's

Various forms of packaging and parts for early STC Transistors. Including two complete devices and an LS828 junction transistor.
For Synthetic Germanium See Item A1431.

Nortel Collection

A1428

EARLY THERMISTORS AND DIODES FROM STC , 1950's

Six Items from STC at Ilminster. The top three are Thermistors with their Original tube packing.
The bottom three are early diodes, including a Point Contact version, and an early Photo diode P50a or P50b.

Nortel Collection

A1432

FIRST GERMANIUM GROWN BY HENRY WOLFSON MBE AT STC, 1950's

Synthetic Germanium.

The sample shown is the original first sample of Germanium grown by Henry Wolfson MBE in the UK.
And on the right, is a cut down section used for research.
Grown at the Laboratory STC Ilminster Somerset.

HENRY WOLFSON MBE

Henry Wolfson was a prolific inventor and his name is on many patents
He was interested in electronics from an early age.

He knew John Logie Baird and was involved with the Television Society which was formed in 1927, now The Royal Television Society. He was made a Fellow of the T.S. in 1927.

During the 2nd World War he worked on top secret work and was described as a Boffin.
At the end of the war he joined a scientific investigation team touring Germany, he went as a RAF officer.

He was awarded the MBE in 1948





Nortel Collection

A1431

MULLARD OCP71 PHOTO DIODE, 1960's

Mullard light sensitive transistor known as a 'Phototransistor'. As these were more expensive than ordinary transistors, it was found that an OC71 transistor (much cheaper) was also sensitive to light if the paint was remove from its surface. Mullard later changed the jelly surrounding the germanium element inside probably to stop this being possible.

A1437

MULLARD AF115 IN ORIGINAL BOX, 1960's

Mullard germanium Transistor of the 1960's use in Radio receivers for Radio Frequency amplification. Not many of these would still be working today as they suffered from a problem known as 'Whiskering' internally which usually connects the workings inside to the casing and worse, disconnecting the outer shell, which is used as a screen, does not always work.
The price on the box is a massive 7 shillings.

A1436

MULLARD OA5 AND OA10 GERMANIUM DIODES, 1950's

Early Germanium Junction diodes from the 1950's made by Mullard. The OA5 is 'Gold Bonded'. Advantage or Sales pitch!

Nortel Collection

A1435

STC ADY24 TRANSISTOR, 1950's

Discontinued in 1975 Germanium Junction PNP Transistor of the 1950's in a standard TO3 package. Specification =
Hfe50. -80v Collector. Current 1A. Frequency 250Khz.
Typical application is high gain industrial servos

Nortel Collection

A1434

PHILCO 2N353 POWER TRANSISTORS, 1950's

Germanium Alloy junction Power transistor, similar to the T1040 of 1956, giving 12 Watts of power. Using a TO27 package with flexible leads, with the actual transistor mounted inside the dome. Because the standard became the familiar TO3 package this devices life became limited, although in 2010 some of these are still being sold as replacement parts today. Joined presumably a matched pair.

Nortel Collection

A1433

STC SYNTHETIC QUARTZ, 1964

It takes 3 Million years for a Quartz block of this size to grow naturally, this specimen was grown in the STC Harlow Laboratories in 3 weeks.
For its application see Item A1424.

Nortel Collection

A1421

SIX QUARTZ CRYSTAL UNITS MADE BY STC TO THE, 1960's

Various types of Quartz crystal units dating from the 1940's. Quartz crystals are used in many electronic systems for providing stable oscillators, such as Signal Generators, Communication Transceivers, they are used for filters as well, possibly a more common use in modern equipment. Also any equipment that needs to remain stable in operation. Such is the importance of stability in some applications that these units are operated inside temperature controlled ovens. One disadvantage of quartz is that it continues to change over time, over many years the value to which these units are made will vary slightly, causing an error requiring a replacement of the unit. Variation is usually 1 in 1000,000,000 times per day.
For Synthetic Quartz See Item A1421.

Nortel Collection

A1424

BEEHIVE BULB, 1950's

Beehive bulbs were used as night lights for children as well as for illuminating dark areas. Drawing a very small amount of power, as the illumination comes by excited the internal Neon gas from a high voltage, such as mains electricity. When used with Alternating current both elements (both coil and flat plate) will glow alternately, with Direct current only one element will glow depending on the polarity.

One is operating in the museum.

A1597

WWII DUNGENESS LIGHT HOUSE SPARE LAMP

Removed from the lighthouse during WW2 and held in storage since then.
It was removed to prevent subversive organisations from using the light for signalling in the event of an invasion.

A0194

GEC BARRETTER, 1930's

Barretters are temperature sensitive resistors used for stabilising voltages in wireless receivers, usually powering the heater circuits, of AC/DC receivers.
Acting like a resistor but with constant current characteristics, a current over a particular range can be held constant over a range of varying voltage. A Barretter usually consists of an Iron wire held in Hydrogen filled glass envelope. Also used for many other applications.

A0692

ROBERTSON CARBON FILAMENT BULB, 1920's

Robertson Carbon Filament bulb 80 Volt 8 Candle Power
Within a very few years, the Robertson Lamp had proved itself by far the most successful in the UK marketplace. In spite of this lamp being the most expensive on the market, the factory was producing and selling 4 million lamps per year by 1904. The statistic is significant because at the beginning of 1904 the thermionic valve had not been invented, many of the materials, technologies and processes that would be needed for valve making were already in place by virtue of the effort expended on establishing manufacturing of the electric lamp.

A0695

EDISON CARBON FILAMENT BULB, 1900's

This bulb is an Edison 100 volt 16 candlepower carbon filament.
Contrary to popular belief, Edison didn't "invent" the light bulb, but rather he improved upon a 50-year-old idea. In 1879, he used a lower current of electricity, a small carbonized filament, and an improved vacuum inside the globe, he was then able to produce a reliable, long-lasting source of light. The idea of electric lighting was not new, and a number of people had worked on, and even developed forms of electric lighting. But up to that time, nothing had been developed that was remotely practical for home use. After about one and a half years of work, he produced an incandescent lamp with a filament of carbonized sewing thread that burned for thirteen and a half hours.

A1275

CARBON FILAMENT LIGHT BULB, 1900's

There are no markings on this bulb.
Joseph Wilson Swan (1828-1914) was a British physicist and chemist. In 1850, he began working with carbonized paper filaments in an evacuated glass bulb. By 1860 he was able to demonstrate a working device but the lack of a good vacuum and an adequate supply of electricity resulted in a short lifetime for the bulb and an inefficient source of light. By the mid-1870s better pumps became available, and Swan returned to his experiments.
Thomas Edison (1847-1931) began serious research into developing a practical incandescent lamp in 1878. Edison filed his first patent application for "Improvement In Electric Lights" on October 14, 1878
After many experiments with platinum and other metal filaments, Edison returned to a carbon filament. The first successful test was on October 22, 1879, and lasted 13.5 hours. Edison continued to improve this design and by Nov 4, 1879, filed for a U.S. patent for an electric lamp using "a carbon filament or strip coiled and connected ... to platina contact wires."
Although the patent described several ways of creating the carbon filament including using "cotton and linen thread, wood splints, papers coiled in various ways," it was not until several months after the patent was granted that Edison and his team discovered that a carbonized bamboo filament could last over 1200 hours.
On December 13, 1904, Hungarian Sondor Just and Croatian Franjo Hanaman were granted a Hungarian patent for a tungsten filament lamp in Budapest, which lasted longer and gave a brighter light than the carbon filament.
Tungsten filament lamps were first marketed by the Hungarian company Tungsram in 1905, so this type is often called Tungsram-bulbs in many European countries.

A1311

EARLY LIGHT BULB, 1900's

Probably used as a test unit for low voltages in a workshop or laboratory

A0852

SIEMENS CARBON FILAMENT 220 VOLT LIGHT BULB, 1900's

Early light bulb made by Siemens with carbon filament.
Like Robertson many companies started producing carbon filament lamps once the Edison Patent had expired.
For more information see Item A0695.

A0696

DUAL FILAMENT LIGHT BULB 115 VOLT, 1920

Unique Lamp with two Filaments and three connections on the Bayonet base, turning a ring around this moved the locating pins to the other connection. If the first filament blows, simply turn to the other one.

A1274

ROYAL EDISWAN TUNGSTEN FILAMENT 130 VOLT BULB, 1930's

Bulb used in Trolley Buses and Trains up to and during the 1930's.

A0698

10,000 WATT LIGHT BULB, 1950's

Large 10,000 Watt lamp.
Uses uncertain, probably a stage lamp, or small Lighthouse.
A similar bulb can be seen in the opening credits to the TV show Time Watch.

A0691

BRIMAR TUNOGRAPH TUNING INDICATOR, 1933

The Brimar 'Tunograph' is essentially a visual resonance indicator, and as such can be used in a radio receiver to facilitate and indicate correct tuning. This is the result of research to provide a means of inexpensively indicating the strength of tuned radio signals. In the 1930's the Superhetrodyne receiver was becoming more popular, this enabled automatic gain control to stop the overloading of tuned signals and provide maximum sensitivity for weak ones. The AGC circuit produced a flat output response from the Intermediate stages of the receiver making it difficult to tune to the strongest part of the signal. Tuning indicators were the answer to this problem,
The following was taken from Brimar Sales documentation.

'' In receivers employing automatic volume control, many people experience considerable difficulty in tuning accurately to the wanted station. When the Brimar 'Tunograph' is employed, however, this is simplicity in itself. The 'Tunograph' is a modification of the well-known Standard Telephone's Cathode Ray Oscillograph tube, (item A1304) operating on precisely the same principal, but produced at an extremely competitive price for incorporation in radio receivers.''

Once launched the Tunograph was overtaken in 1935 by the American RCA 6E5G which rendered it obsolete overnight.
It is a small cathode-ray tube, where the electron current from the cathode, was focused into a narrow beam and passed through a hole in the anode to a fluorescent screen. A pair of plates were used to deflect the spot and this deflection depended upon the signal strength.

Nortel Collection

A1303

6E5G TUNING INDICATOR OR MAGIC EYE, 1935

The designers of the first 'Magic Eye' registered their first electron-ray tube, the 6E5, on June 27, 1935. This tube initially appeared in RCAs' console-model product line that same year. RCA was fearing a loss of market share to competitors' new lines of very small and midget radios, many of which were designed and produced in Los Angeles. RCA's promotion touted the "Magic Eye" as an elegant feature of their upper product line - where profit margins were greatest.
Not surprisingly, the 6E5 wouldn't fit inside the competitors' smallest sets. The name "Magic Eye" quickly gained acceptance with the public as the standard identity for the electron ray tube and tuning eye feature in consumer radio sets, regardless of manufacturer.
The tube shown has a concave disc inside that is illuminated on the sides of the bottom edge as the signal is increased the two illuminated edges move towards each other in an arc until they touch at full signal.

A1325

TV4 TUNING INDICATOR AND BOX, 1936

The TV4 was the first British magic eye on the market, Launched in the summer of 1936. It was more compact than other available types, and after problems with reliability and a short life, the internal structure was modified to correct the problem. It Has side contact Ct8 Base.
It also has a standard British 4.0 Volt heater.

• Box for the Tuning Indicator
  

A1326

MULLARD EM1 TUNING INDICATOR MAGIC EYE, 1936

Mullard end viewing Tuning Indicator with side contact base type Ct8. The EM1 followed the TV4 . The EM1 was introduced to eliminate the problems associated with the old TV4, and had a 6.3v heater.
The tube shown has a concave disc inside that is illuminated on the sides of the bottom edge, as the signal is increased the two illuminated edges move towards each other in an arc until they touch at full signal.

A later version of this the EM34 can be demonstrated.

A0683

AC/ME MAZDA TUNING INDICATOR or MAGIC EYE, 1936

Mazda AC/ME early Tuning Indicator. The tuning indicator tube, or "Magic Eye" as it is was introduced by RCA, was used to display the optimum signal tuning point of a tuner/receiver, or the peak signal level of a pre-amplifier or tape recorder. This tube appeared soon after RCA's 6E5.

A0690

RCA 1629 TUNING INDICATOR OR MAGIC EYE, 1930's

R.C.A. 1629 Tuning Indicator end viewing. The 1629 has a 12V heater and was used as a tuning indicator in the Command set Transmitter.
Not unlike the 6E5 but later and more modern than the 6E5GT.

A0687

MULLARD EFMI TUNING INDICATOR or MAGIC EYE, 1930's

Based on the EM1 Item A0683 this indicator also contains an AF amplifier facility, not actually two valves in one but with amplification incorporated with an amplification factor of 60 maximum. This can reduce the number of valves in a circuit by one in many applications, making this valve unique. The tube shown has a concave disc inside that is illuminated on the sides of the bottom edge as the signal is increased the two illuminated edges move towards each other in an arc until they touch at full signal.

A0686

6AF6 RCA TUNING INDICATOR or MAGIC EYE, 1930's

RCA 6AF6 End viewing Tuning Indicator. An updated version of the 6E5 launched in 1935.

A0685

COSSOR NEON TUNEON TUNING INDICATOR, 1934

Small neon lamps that are used as indicators in electronic equipment. Called "Tuneons" in the 1930s radio sets, that were fitted with the new Tunograph (Item A1303) which could improve the stability and strength of the signal.
However such a device was not cheap, the Tuneon was no more than a modulated neon, and at a lower cost, but it did do what was intended.
Not many receivers were manufactured using this device, as the new RCA 6E5G came out in 1935, at the same cost as an ordinary valve.

This item can be demonstrated.

A0684

DM160 CV6094 INDICATOR VALVE, 1950's

Not actually a Tuning Indicator.
When conducting the DM160 will give out light and goes dark at cut-off. In this way it can be used to indicate the logic state of the circuit it connects to.

In 1969 Mullard describe the DM160 as: a special quality directly heated sub miniature voltage indicator for use in industrial equipment such as transistorised computers.

A0680

EM81 MULLARD TUNING INDICATOR or MAGIC EYE, 1960's

Mullard EM81. The tuning indicator tube, or "Magic Eye" as it is was called when introduced by RCA in 1935, was used to display the optimum signal tuning point of a tuner/receiver, or the peak signal level of a preamplifier or tape recorder,this is Mullard's 1960's version. The main benefit in tuning reception was for FM tuners where the exact tuning point was harder to determine than for AM. The indicator tube is a standard thin glass tube envelope with a reflective arched disc inside called the target. The electrode structure is based on a double triode with common cathode. The anode of the second triode is called the target and within the electron stream is a deflector electrode designed to alter the path of the electron beam, it would normally be connected to the anode.
The tube shown has an arched disc inside that is illuminated on the sides of the bottom edge as the signal is increased the two illuminated edges move towards each other in an arc until they touch at full signal.

This item can be demonstrated.

A0678

DM70 TELEFUNKEN TUNING INDICATOR, 1960's

Telefunken DM70 Tuning indicator for Battery sets. Used to display the optimum signal tuning point of a tuner/receiver, or the peak signal level of a pre-amplifier or tape recorder. The main benefit in tuning reception was for FM tuners where the exact tuning point was harder to determine than for AM.
The front of the tube has a black area with an exclamation mark cut into it, the dot is illuminated green with a small portion of the top of the mark also green (when no signal is present) as the signal is increased the area at the top of the mark moves towards the dot until it touches at full strength.

This item can be demonstrated.

A0679

EM84 MULLARD TUNING INDICATOR OR MAGIC EYE, 1960's

The Mullard EM84 front viewing tuning indicator. The tuning indicator tube, or "Magic Eye" as it is was introduced by RCA, in 1935. It was used to display the optimum signal tuning point of a tuner/receiver, or the peak signal level of a pre-amplifier or tape recorder. This is Mullard's latest version
The main benefit in tuning reception was for FM tuners where the exact tuning point was harder to determine than for AM. The indicator tube is a standard thin glass tube envelope with a fluorescing strip inside just beyond the target anode. The electrode structure is based on a double triode with common cathode. The anode of the second triode is called the target and within the electron stream is a deflector electrode designed to alter the path of the electron beam, it would normally be connected to the anode.

This item can be demonstrated. The tube has a white strip inside mentioned above that is illuminated on the ends as the signal is increased the two illuminated edges move towards each other until they touch at full signal.

The Museum can demonstrate several different "Magic Eyes"

A0677

TETRODE VALVES USED IN SHELL FUZING WW2, 1940's

Developed possibly by Western Electric or STC at Harlow for use in Proximity Shell Fuses (See Item A0478 and A0430). It is not known if they were ever used for this purpose, as many manufacturers were asked by the British Government during WW2 to come up with a solution to the problem, of shells that would explode in the proximity to Aircraft, the biggest problem being finding a valve that could be fired from a gun and survive, (pre guided missiles) The Example of a British proximity fuse that we have (possibly one of the only surviving examples) does not use this valve. This type may well have been used in the later American version (Item A0430) which used the new Technology, 'Radar' a Phrase coined by the US, (RAdio Direction And Ranging)

A1425

RAF TYPE 'C' MOV VALVE, 1918

Valve made by the Marconi Osram Valve Co for the British Air Force around September 1918.
It is a High Vacuum Triode with a Tungstan filament, 3volt 0.75 Amps with an amplification factor of around six.

Nortel Collection

• Box for the Valve
  

A1305

BTH T5-230 VALVE, 1920's

This valve is post 1920 owing to evidence of Gettering (the blackening inside) only used after 1920.
Clearly marked BTH T5-230 a Naval Transmitting type first produced in 1919, with a candelabra cap but instead of two wires at the other end, it is fitted with a later three connection base normally used with RAF valves.
Also the candelabra cap has only one connection, for the filament the other filament wire is brought out to the tip on the other end, with anode and grid on the sides.

Nortel Collection

A1301

WW1 AEG TYPE "A" VALVE

made by AEG and used during the First world War by the Germans, and was used as a Telephone repeater amplifier
AEG the Company translated means General Electricity Company AEG was founded in 1883 by Emil Rathenau who had bought some patents from American inventor Thomas Edison.

A0787

EA50 VALVE, 1930's

EA50 Diode pre WWII, used in early television as a detector, and general signal rectification.

A0619

MOV DET25 VT25 CV1025 EDISWAN VALVE, 1932

This valve has an Anode of solid Graphite. Marconi Osram Valve Co DET25,
Made by Ediswan

A0661

WWII VT17 VALVE

VT17 Tetrode Transmitting Valve

A0927

446B-SC278A RCA LIGHTHOUSE VALVE, 1942

RCA 446-B microwave Triode used by the US Navy and known as a Lighthouse valve.

A0668

CV52 UHF TRIODE VALVE, 1942

Used as a Local Oscillator in the R1294 Microwave Search Receiver, up to 1GHz is possible and even higher using harmonics

Wartime UHF Triode of 1942.

A0665

WWII 4671 ACORN VALVE

Acorn 955 Triode 1934 followed by 954 and 956 Pentode

The Valve known as an Acorn, was one of the fist truly miniature valves and was used in Military equipment during WW2. In the 1930's RCA produced the Acorn valves consisting of a 955 Triode in 1934 followed by the 954 Pentode in 1935 and.variable-mu pentode 956, in 1936.
With an upper working frequency of 400Mhz these valves were mass produced in the USA during the Second World War for a lot of electronic equipment and a large number were imported into the UK.
These valves were not used in Proximity shell fuses, simply not robust enough.

A0620

MULLARD EF50 VALVE, 1939

EF50 Originally developed by Philips in 1939.
Used in Radar receivers and other equipment.

Mullard Pentode valve of 1939, used in many military Transceivers.

A0613

WWII TELEFUKEN P700

Valve produced during the Nazi period in Germany 1933 to 1945, and used in many Transmitters and Receivers of that period.

A0612

GT1C GEC COLOSSUS VALVE, 1939

Used in the Colossus computer at Bletchley Park. During the rebuild of the first electronic computer in the world, engineers involved in the project were serching world wide for all the valves of this type they could find as the machine used several hundred.
It is an Argon filled electronic switch. This thyratron found many uses as a timebase for radars, and in particular many were used in the Colossus computer which was used a Bletchley Park to crack the codes of the German Lorenz cipher machines.

A0599

WWII MOV PT15/ VT104 10E/215

The RAF used this valve in the 1154 transmitters placed in WW2 Bombers
See Item A0164.
It is a 25Watt RF Pentode.

A0591

TRIGATRON CV85 SPARK GAP 24B9, 1959

Enclosed spark gap.Three electrodes two for switching a high power high voltage and the third for triggering the device into conduction.
If the trigger is connected to a transformer producing a high voltage pulse, the gap between the two electrodes becomes Ionized, this forms a conducting area between the two electrodes and the device switches on, passing large currents and high voltages.
Used in pulsed Radar circuits. Specification:- 150KWatt 7.4 Kvolt 80 Ohms on resistance Frequency 2.5 Khz. Protected by a gauze sock, to contain the glass should the device shatter.

A0208

NU22C SILICA VALVE, 1937

The Navy used these valves, The envelope is made of Silica Glass. The advantage being that the envelope could be opened, the unit repaired and easily resealed and evacuated of air. More importantly Silica glass can pass higher proportions of Infra red and has a higher melting point, so the anode of the valve can run at higher temperatures. This is a half wave rectifier of 1937.

A0642

MULLARD 5-10 AMPLIFIER of 1959

Mullard in their Book ‘Circuits for Audio Amplifiers’ in 1959 included the Mullard 5-10 amplifier; the book cost 8/6d, and it was an immediate success for amateur builders of the time. The amplifier incorporated 5 X valves 2 EL84's in the output stage operating in 'Push Pull' mode an ECC83 as Buffer and phase splitter together with an EF86 first stage and an EZ81 as a full wave rectifier. Producing 10 Watts at less than 0.03% harmonic distortion into a 15 Ohm loudspeaker, this was Monophonic sound, two units would be required for Stereo, but this was still in it's infancy in 1959, and Mono recordings were still being sold at the time. This unit was built around 1964 by the author who had previously made the Mullard 3-3 amplifier, see item A1647. A Pre amplifier was also shown in the same book and included crystal pick up magnetic pick up, and Radio and Microphone inputs, a stereo version was also available, the author used a Decca Deram ceramic cartridge with the mono 2 X valve unit.

A1646

MULLARD 3-3 AMPLIFIER of 1959

Mullard in their Book ‘Circuits for Audio Amplifiers’ in 1959 included the Mullard 3-3 amplifier; the book cost 8/6d, and it was an immediate success for amateur builders of the time. The amplifier incorporated 3 X valves 1 EL84 in the output stage an EF86 first stage and an EZ80 as a full wave rectifier. Producing 3 Watts at less than 0.05% harmonic distortion into a 15 Ohm loudspeaker, this was Monophonic sound, two units would be required for Stereo, but this was still in it's infancy in 1959, and Mono recordings were still being sold at the time. This unit was built around 1963 by the author who had later made the Mullard 5-10 amplifier, see item A1646. The author used a Decca Deram ceramic cartridge with this unit. On the front are controls for volume treble and bass, the knobs are not fitted.

A1647

HIVAC XY 1.4A VALVE, 1940's

Triode valve of 1937 for small battery equipment. Similar to the type used in the Proximity fuse Item A0478 but not as robust.

A0617

MINITURE VALVE TYPE CV480 TETRODE, 1940's

Pre Transistor Valves got smaller in an attempt to miniaturize equipment, particularly military items. This was just one unit made by STC at Harlow either before or during WW2. A Tetrode marked CV480-789

NORTELL COLLECTION

A1423

KERR CELL, 1930's

This is not a Baird grid cell but a similar type. A Kerr cell is a device for the electrical modulation of light. The cell consists of a transparent container filled with nitro-benzene. Polarized light is passed through the liquid and between two banks of metal plates resembling the plates of a variable capacitor. As the potential across the two banks of plates is varied, so the polarised light beam is more or less rotated, away from the axis of rotation. Baird used these in experiments for television and one is present in his 'Televisor'. Further research was done to try and produce high definition television but this was unsuccessful due to the internal capacitance of the cell. A further drawback not directly connected with the Kerr cell, is the fact that light-modulation of this type is of use only with mechanical methods of scanning, and these, in themselves, are clumsy and unsatisfactory for high definition. Rev. John Kerr (1824 - 1907) was a Scottish physicist who inaugurated the field of electro-optics.

A1383

STC V240C/2K, 1940's

Known as a Velocity Modulated Valve or 'Heil' tube for use as a Microwave a oscillator and requires a magnetic field for operation with the Anode connected by a Housekeeper seal (the copper disc), invented by A.A.A. Housekeeper, who solved the problem of making ductile metals bond to glass.

In1935 A. Arsenjewa-Heil and O. Heil (wife and husband) were acknowledged for their contribution to velocity modulation theory .

A0643

COLD CATHODE OR TRIGGER TUBE, 1950's

Cold Cathode tube loosely referred to as a trigger tube, used in electronic calculators having three elements a cathode anode and trigger element.
The tube fires and glows when a voltage is applied to the trigger when a negative voltage is on the cathode and a positive voltage on the anode.
The tube will only extinguish if the anode voltage is removed.
Many devices can be connected in a line (10) for counting application, as in Sumlock Comptometers 'Anita' Calculators, used in the 1960's. The early computers of the 1940s and 1950s used the mature vacuum tube technology of the day. In the 1950s and early 1960s transistors were new and undergoing rapid development.
They were also expensive and prone to failure if badly treated electrically.
So it is no surprise that the first commercially successful electronic desktop calculator used vacuum tube technology.

A0702

HIVAC TRIGGER TUBE, 1950's

Device triggers like a neon at certain predetermined voltage , The trigger tube other wise known as a cold cathode tube fires or triggers when the voltage across is high enough. Can only be extinguished by lowering or removing the voltage.
Unlike normal valves there is no heater required hence the term cold cathode.

Used in oscillator circuits.

A0856

STC R3 VALVE, 1920's

Made by STC in their Micromesh range, it is a rectifier valve of the late 1920's

A0631

MARCONI ROUND 'CA' VALVE, 1913

First produced in 1913 the grid and anode connection are on the side, the tube at the top contains asbestos which when heated drive a gas into the body of the valve and thus the vacuum could be brought to a proper degree of softness and thereby restore the characteristic curve to it's normal shape. The soft vacuum three electrode valve intended as an amplifier was much superior to any which had preceded it. The third electrode was introduced by Lieben- Reisz (Germany) and Dr. Lee de Forest (USA).
The electrode consist of a nickel cylinder, nickel grid, and hairpin platinum filament coated with a mixture of barium and calcium oxides.

Nortel Collection

A1309

FLEMING DIODE COMMERCIAL TYPE, 1910's

A commercial type of the original Fleming diode, it has a flat plate anode and is covered in a gauze screen to protect it from external electric fields.
These valves were made for companies by the Edison Swan Company probably at its Ponders End factory.

Nortel Collection

A1310

TELEFUNKEN EVE173 VALVE, 1914

Copied and developed by the Germans after they had captured examples of the French hard valve during WW1
This EVE173 has a nickel anode and grid.
Around 1918, because of the shortages of material in Germany, the anodes were made of copper and in some cases the grids as well.
The filament is 0.55amps 2.8volts Anode 40-70 volts.

Nortel Collection

A1308

TELEFUKEN RS5 VALVE, 1918

The R.S.5. was an RS4 with improved performance being produced at a rate of 25 per day in 1918.
It operated with a filament current 3 amps from 8 to 12 volts depending on the valve, with 400 volts on the anode the output was 5 watts, with 600-800 volts it could be 10 to 20 watts.the valve was also made by Siemens and Halske, the glass work inside is of an excellent type.
The valve is designed for possible oil immersion to facilitate cooling.

Nortel Collection

A1307

MARCONI RECTIFIER MR1 VALVE, 1919

Marconi MR1 (Marconi Rectifier No1). Similar to the unit that would have been used to power the transmitter for the first broadcast from Savoy Hill in 1922, in which Dame Nelly Melba Sang.
The unit was used to turn the Mains Voltage which was Alternating Current into Direct current for the High Tension supply of the Main Transmitting valves.

A0713

CATHODE RAY OSCILLAGRAPH, 1930's

A Later version having an Octal base, of the Brimar 'Cathode-Ray Oscillagraph', similar to the 'Tunograph' but used to monitor modulating current for experimental purposes.
The spot of light produced on the screen at the top could move across the screen in three dimensions. Unlike the 'Tunograph'. The earliest version of the CRT was invented by the German physicist Ferdinand Braun in 1897 and is also known as the Braun tube.
It was a cold-cathode diode, a modification of the Crookes tube with a phosphor-coated screen.

Nortel Collection

A1304

MULLARD U30 RECTIFIER VALVE, 1920's

Early Rectifier valve made by Mullard Valves in the early 1920's.

Maker known then as the Mullard Wireless Service Company Ltd

A0789

OSRAM GEC BARRETTER, 1930's

Barretters are temperature sensitive resistors used for stabilising voltages in wireless receivers, usually powering the heater circuits, of AC/DC receivers.
Acting like a resistor but with constant current characteristics, a current over a particular range can be held constant over a range of varying voltage. A Barretter usually consists of an Iron wire held in Hydrogen filled glass envelope. Also used for many other applications.

A0693

A SELECTION OF EARLY TRANSISTORS AND MINIATURE VALVES, 1950's

A Selection of Transistors and miniature valves, also a mercury wetted relay with box.
There is a glass microscope slide showing the parts of a Germanium Transistor, a sectioned point contact diode showing the cats whisker, a U25 Extra high voltage rectifier used in Televisions, a Neon number indicator made by Mullard, and a solid state infra red detector.
Also are various early, and not so early transistors.

Nortel Collection

A1322

ENGLISH ELECTRIC TRAVELLING WAVE TUBE N1001 VALVE, 1963

Micro Wave amplifying device that works by slowing the electrons through a coil of wire so that the beam of electrons running through it are caused to bunch. The signal through the wire is slower because it has further to travel, hence the name,Travelling Wave Tube.
The bunching of electrons inside the coil is caused by interaction with the beam passing through it, at the first area of bunched electrons some energy is imparted back to the coil, as the process continues the bunch grows so that the next area of bunching becomes larger. this process continues all the the way to the end of the tube.
Travelling Wave Tubes are used in Micro Wave link amplifiers and satellite systems.

A0857

NIXITUBES ZM1040 AND ZM1020, 1960's

Glass tubes with 10 numbers inside one behind the other, viewed from the front and filled with neon gas. as each number is connected to a high voltage it glows. One side view and one end view. Used in Calculator machines such as the 'Anita' See Item A1157. The early computers of the 1940s and 1950s used the mature vacuum tube technology of the day. In the 1950s and early 1960s transistors were new and undergoing rapid development. They were also expensive and prone to catastrophic failure if badly treated electrically. So it is no surprise that the first commercially successful electronic desktop calculator used vacuum tube technology.

A0854

OSRAM CMG8 PHOTO CELL VALVE, 1937

Osram CMG8 or CV1432 early Photo Cell,of the Caesium type Gas filled. Designed for acoustic reproduction and general purpose applications.

A0712

CONTINENTAL ELECTRIC SC609A PHOTO CELL VALVE, 1920's

Early Photo Cell possibly for Movie projectors with sound and other applications.

A0711

CAGO68T PHOTO CELL, 1920's

Early Photo Cell for detecting light, origin unknown.

A0710

PHOTOMULTIPLIER VALVE, 1960's

Photomultiplier tubes (photomultiplier's or PMTs for short), members of the class of vacuum tubes, and more specifically photo tubes, are extremely sensitive detectors of light in the ultraviolet, visible and near infra-red. These detectors multiply the signal produced by incident light by as much as 100 million times (i.e., 80 dB), enabling (for example) single photons to be individually detected when the incident flux of light is very low. The combination of high gain, low noise, high frequency response and large area of collection has earned photomultiplier's an essential place in nuclear and particle physics, astronomy, medical diagnostics including blood tests, medical imaging and motion picture film scanning (telecine). Semiconductor devices, particularly avalanche photo diodes, compete with them, but photomultiplier's are uniquely well-suited for applications requiring low-noise, high-sensitivity detection of light which is imperfectly collimated. While photomultiplier's are extraordinarily sensitive and moderately efficient, research is still under way to create a photon-counting light detection device that is >99% efficient; such a detector is of interest for applications related to quantum information and quantum cryptography. Elements of photomultiplier technology, integrated differently, are the basis of night vision devices.
The photomultiplier, invented in 1936, is rooted in the science of the photoelectric effect, and that of secondary emission - i.e., the ability of electrons in a vacuum tube to, by striking an electrode, cause the emission of additional electrons.
Photomultiplier's are constructed from a glass vacuum tube which houses a photo cathode, several dynodes, and an anode. Incident photons strike the photo cathode material which is present as a thin deposit on the entry window of the device, with electrons being produced as a consequence of the photoelectric effect. These electrons are directed by the focusing electrode towards the electron multiplier, where electrons are multiplied by the process of secondary emission.

A0709

DECATRON CV2325 TUBE, 1960's

Decatron decade counting tube basically ten cold cathode tubes in one.
A Decatron is a gas-filled tube. Dekatrons were used in computers, calculators and other counting-related devices during the 1940s to 1970s. "Dekatron," now a genericized trademark, was the brand name used by Ericsson Telephone. Internal designs vary by the model and manufacturer, but generally a dekatron has ten cathodes and one or two guide electrodes plus a common anode. The cathodes are arranged in a circle with a guide electrode (or two) between each cathode. When the guide electrode(s) is pulsed properly, the neon gas will activate near the guide pins then "jump" to the next cathode. Pulsing the guide electrodes repeatedly will cause the neon dot to move from cathode to cathode.

A0707

RAYTHEON 2J50 MAGNETRON VALVE, 1980's

Magnetron for Microwave communications.
This device is connected directly to wave guides and is used for transmitting on 3cm Radars.

A0708

15R EIMAC VALVE, 1940

Eimac 15R Diode of 1940.

A0701

5 C-450A STC VALVE, 1950

Pentode amplifying valve of 1950.

A0647

AJ20 COSSOR 80P 35 VALVE, 1930's

Triode valve for audio use.

A0593

STC MERCURY VAPOUR 3V/531E VALVE, 1940's

Mercury vapour type rectifier made by S.T.C.

A0651

CV35 KLYSTRON REFLEX VALVE, 1942

CV35 Reflex Klystron of 1935. A klystron is a specialized velocity modulated vacuum tube (evacuated electron tube). The pseudo-Greek word klystron comes from a Greek verb referring to the action of waves breaking against a shore, and the end of the word electron.
The reflex klystron contains a REFLECTOR PLATE, referred to as the REPELLER, instead of the output cavity used in other types of klystrons. The electron beam is modulated as it was in the other types of klystrons by passing it through an oscillating resonant cavity, but here the similarity ends. The feedback required to maintain oscillations within the cavity is obtained by reversing the beam and sending it back through the cavity. The electrons in the beam are velocity-modulated before the beam passes through the cavity the second time and will give up the energy required to maintain oscillations. The electron beam is turned around by a negatively charged electrode that repels the beam. This negative element is the repeller mentioned earlier. This type of klystron oscillator is called a reflex klystron because of the reflex action of the electron beam.

In1935 A. Arsenjewa-Heil and O. Heil (wife and husband) were acknowledged for their contribution to velocity modulation theory .

A0666

8012 RCA VALVE, 1940

8012 RCA UHF Triode of 1940.It was used in equipment designed for jamming German Radar, particularly the APQ9 Radar jamming unit.

A0664

BT5 THYRATRON VALVE, 1938

BT5 Thyratron made in 1938 by A.E.I. in there Lincoln factory, which later became the Semiconductor division.

A0660

GT5E GAS FILLED RELAY OSRAM TRIODE, 1940's

Osram Gas filled relay, actually a triode valve acting as a high power switch.

A0657

DA 100 TALKIE VALVE, 1930's

Power amplifier Triode Made by the Marconi Osram Valve Company, with a capability of 100 Watts. Using Molybdemum electrodes and Oxide coated filament designed specifically for use in output stages of power amplifiers.
A pair of valves could be used in push pull, class AB with low distortion, generating 200 Watts.
The valve became well known in PA amplifiers. It was also used in the modulator chain of the Marconi SWB8 and SWB10 transmitters.
As it was used in Cinema amplifiers it became known as the 'Talkie Valve'.

A0646

450 TL EIMAC VALVE 1930's, 1940's

High Powered Triode, made in the late 30's early 40's.

A0650

388A WESTERN ELECTRIC DOOR KNOB VALVE, 1938

Western Electric 388A UHF Triode of 1938.

A0652

CV1076 DA41 MOV VALVE, 1930's

Power triode with Anode connection made to the top cap. The valves had carbon anodes with a dissipation of 40 Watts and were designed to work in Push-Pull pairs operating in class B. This class of audio circuit was both inexpensive and very efficient.

It was estimated that an output of 175 Watts could be obtained by a pair of DA41/2's working at an anode voltage of 1,000 Volts. Using a Thoriated filament at 7.5 volts 2.5 amps.

A0596

CV19/J RECTIFIER, 1940's

Rectifier up to 250KV @ 123Ma

A0200

2G/47 4C STC, 1930's

High voltage rectifier, with large Edison screw base.

A0587

SU750 COSSOR, 1930's

High Voltage Rectifier Valve, with twist base.

A0589

RAYTHEON B-H TYPE B VALVE, 1930's

Raytheon BH type B Cold Cathode Rectifier.
This valve has no heater.

A0610

XP2 HIVAC MINITURE VALVE, 1936

Triode of 1936 with a DA4 pin base.

A0615

EARLY COSSOR X-RAY TUBE, 1900's

An early X-Ray tube that has been over driven by Mr Lee, Causing an element to drop, before he donated it to the museum. On the top is a pillar containing Asbestos which when charged by high voltage re-gassed the tube.

The firm A.C.Cossor Ltd was established in 1859, making Scientific glassware.
Cossor Electronics started in 1875.

A0639

JENNINGS 12Pf CAPACITOR VC12, 1940's

Glass vacuum capacitor value 12 Pf 20kv extremely low leakage.

A0210

GEC PR 3B, 1930's

High voltage rectifier.

A0586

SU2150A CV 1120 COSSOR, 1936

High Voltage Rectifier Valve, used in pre war oscilloscopes and other equipment.

A0594

OSRAM BARRETTER ON GPO BASE, 1930's

Barretters are temperature sensitive resistors used for stabilising voltages in wireless receivers, usually powering the heater circuits, of AC/DC receivers.
Acting like a resistor but with constant current characteristics, a current over a particular range can be held constant over a range of varying voltage. A Barretter usually consists of an Iron wire held in Hydrogen filled glass envelope. Also used for many other applications.

A0694

GPO VT No 4 VALVE, 1920's

GPO VT No 4 Valve, a Triode of the 1930's on an American UV4 pin twist on base.

A0640

GPO VT32, 1925

Early Telephone Triode amplifier of 1925, with BPO twist on base.

A0644

CV257 MOV HOUSEKEEPER SEAL VALVE, 1943

CV257 Triode Valve used in VHF power amplifiers, with the Anode connected by a Housekeeper seal (the copper disc), invented by A.A.A. Housekeeper, who solved the problem of bonding ductile metal to glass.

A0673

GEC TRANSMITTER POST OFFICE TELEPHONES, 1950's

GEC ACPT21 weight 36Kg's 665mm high 2Ft 2inch long hence the two handles for lifting. ACPT= Air Cooled Pentode Transmitter.
Transmitting Valve used by Post Office Telephones.

A0215

REFLEX KLYSTRON VA22A VALVE, 1950's

Reflex Klystron VA22A used in Radar and communications.

A0853

WWII 708A WESTERN ELECTRIC VALVE

Western Electric 708A Radar Oscillating Triode of WW2.

A0675

CV 1098 VT 98 MOV 'CHAIN HOME LOW' VALVE, 1936

Thoriated Filament version of the VT58 Pulsed Radar Triode of 1936.
The valves were used in the Chain Home Low transmitters during the beginning of WW2 of such importance in the Battle of Britain.
50 KWatts at 200Mhz using two valves in push pull, of pulsed power.
Developed from the ACT10, the air cooled version of the CAT15.

A0649

DET12 4304CB MOV VALVE, 1939

The Marconi Osram Valve Company developed the DET12 in 1939 a Triode of up to 50 Watts for Microwave frequencies in pulsed Radar down to 1 metre, an unusual valve as both the grid and anode is taken out from the top wires.

It also found favour in early developments of VHF wireless transmitters for police use.
Sergeant Octaloni of the Manchester Police was a regular visitor to the MOV Factory on this project in the years before the Second World War.
The valve was used as the transmitter in the base station.

A pair of prototypes were used in the A1 Radar transmitter developed at Bawdsey Manor, and the T1131 Ground to Air Transmitter.

A0663

WWII CV64 RESONANT CAVITY MAGNETRON VALVE

Almost identical to the 1st device made in the UK by GEC for use with Radar, on the 29th June 1940, this was copied by the U.S. during WW2 with permission from Winston Churchill.
The CV64 is a later version of the first Cavity Magnetron the E1189 or CV38.
The magnetron is electrically a diode and in use the flat sides of the central cavity are located between the poles of a powerful magnet (1,350 Gauss).
The magnetic field causes the electrons to spiral outward from the cathode to the anode. The cavities in the anode block produce the powerful microwave energy.

A0670

VT90 MICROPUP VALVE, 1939

The VT90 was the original 'Micropup' developed by the Marconi Osram Valve Company in 1939, operating 200 MHz and used in early airborne Radar. It was used in early Marks of AI and ASV radar.

A0672

COSSOR CATHODE RAY (OSCILLOGRAPH) TUBE, 1937

Early electrostatic Oscilloscope (Oscillograph) tube with rounded face.
Known at this time as an Oscillograph tube, and used for the display of oscillating waveforms. The Type J screen gave a light blue response, and the Type H gave a sepia toned picture. Sizes of this range of tubes went up to 10 inches.

IN 1937 Radar had not been developed yet and TV was still in its infancy, EMI had not yet developed 405 line TV, and Baird was still in competition with EMI with his Televisor.

Type 3276 Dated 1937
The firm A.C.Cossor Ltd was established in 1859, making Scientific glassware.
Cossor Electronics started in 1875.

A0188

V24 MOV VALVE, 1916

Valve designed by H.J.Round (Captain) . A high frequency amplifying Triode of 1916 still being used in 1937.

A0627

D43 MARCONI VALVE, 1938

Marconi D43 single Diode Valve of 1938.

A0611

WECO VALVE, 1920's

Called the Weco (Western Electric Company) or Peanut Valve. Mullard also produced this valve. Ideal for battery equipment with a nominal 1Volt quarter amp heater, and only 17-45 volts anode.

Introduced by the Western Electric Company in 1919 and developed originally by Hendrik Johannes Van der Bijl as the 215A

The Mullard version complete with 4 pin adapter was advertised in The Meccano Magazine in 1924 for 30 shillings.

A0614

WESTERN ELECTRIC WECO VALVE, 1921

Made in Britain from the American version with a British 4 pin base.
Also made by B.T.H.Co. and called the Weco Valve. Mullard also produced this valve. Ideal for battery equipment with a nominal 1Volt quarter amp heater, and only 17-45 volts anode.

Introduced by the Western Electric Company in 1919 and developed originally by Hendrik Johannes Van der Bijl as the 215A

A0861

MULLARD EE50 VALVE, 1939

Unique valve made by Mullard in 1939, which was never fully produced , no known equipment ever used it.
This sample was found in a cellar at a Radio/TV manufacturer (Bush), probably engineering sample.
The base is a locking type with bent pins to 90 degrees.

Donated by Ray Whitcombe

A0993

MICROMESH PENTODE, PEN B1., 1930's

Standard Telephones and Cables stopped trading their Micromesh range of valves around 1935, This is an indirectly heated Pentode Type PEN B1 output valve, designed for use in battery sets. It has a 2 volt 0.2 amp heater, with a very low HT drain.


Nortel Collection

• Box for the Valve
  

A1302

OSRAM HL410 VALVE, 1928

Osram HL410 was a Battery dull emitter with a 4 volt heater of 1928.

A0633

PHILIPS 'Q' VALVE, 1921

The Philips 'Q' was a space-charge-grid Tetrode, the base had a terminal on the side for the inner grid. With a bright-emitter filament 3.5volts.

Nortel Collection

A1306

'R' VALVE, BBC MARKING AND BASE, 1923

The 'R' Valve was developed from the French hard vacuum valve of WW1 and was made in the UK from 1916 by the Marconi Osram Valve Company. Its use in new equipment declined in 1925 with the introduction of the lower power dull emitter valves.

The first ever broadcast from Savoy Hill in 1923 used these valves in the audio amplifier. This was the first UK Hard Vacuum valve to go into production, historically so important that a company in Europe started making copies for enthusiasts who wished to make early wireless sets work.

A0770

MYERS RAC3 2 VOLT VALVE, 1922

Elmer B Myers one of the directors and chief engineers, designed and marketed the RAC3 Audion aiming for the business of the amateur operator rather than the broadcast trade.
This tube was first advertised in December 1920.
It is a Triode with a 4 volt filament.
Made by the Canadian company, E.B.Myers, of Montreal.

A0641

THORPE K4, 1927

Helix wound anode valve. The Thorpe K4 was a tetrode of the space charge grid type. It was intended primarily for use in the Unidyne or Solodyne circuits which were popular at that time.
The advantage of this valve was that no separate anode voltage supply was required, as both anode and inner grid were fed from the 6 volt filament battery. In the period 1925-1927 the K4 valve was offered for sale by at least three vendors in London, but although distributed by Bower Electric Ltd was not advertised by them.

A0598

LOEWE 3NF VALVE, 1929

3 x triodes, Cathode 4V- anode 90V.
One of the most fascinating valves you will ever see, the Loewe 3NF incorporates three triodes, two capacitors and four resistors in a single glass envelope. The inclusion of the passive components reduced the number of pins required to six, but to avoid them contaminating the vacuum, they are each sealed inside a glass tube.

One of the reasons for the development of this amazing device was that in Germany, there was a tax on receivers based on the number of valves in the set, so in 1926, Loewe Radio A.G introduced the 3NF, and also another multi-valve, the 2HF, which contained two screen-grid tetrodes, two resistors and a capacitor, intended for use as a two-stage RF amplifier.
The original Loewe multi-valves are masterpieces of glass work, which must have been very expensive to manufacture, so later versions used a mica supports, and the glass was given an aluminium outer coating to hide the less elegant internal structure.
An obvious drawback of putting three valves in a single envelope is that if one filament fails, the whole device becomes useless, but to counter this disadvantage, Loewe offered a repair service to replace failed filaments.

A0601

ARCTURUS No 127, 1929

Triode, indirectly heated, with 5 pin Base.
The blue colour was used as a trade mark of the Arcturus Radio Tube Company.

A0600

SIEMENS AND HALSKE 'OR' VALVE, 1922

Tetrode of 1922 made in Germany by Siemens and Halske.

A0602

MULLARD ORA VALVE, 1923

The Mullard ORA Valve of 1923.
The title means Oscillates Rectifies Amplifies.
The three possible main functions of the valve.

Maker known then as the Mullard Wireless Service Company Ltd

A0603

LS3 MOV VALVE, 1920's

The Broadcast station 2LO was listened to by receivers using this valve, known as a loudspeaker valve replacing the need for headphones and speaker horns on crystal receivers. (Loud Speaker valve No3).

A0624

CUNNINGHAM AUDIOTRON VALVE, 1915

The Cunningham Audiotron, used as a detector amplifier.
Launched in 1915 in competition with DeForests Audion Valve.

A0628

DEV MOV VALVE, 1925

The Marconi Osram Valve Companies DEV Triode Valve of 1925, with dull emitter filament. See Item A0630.

A0626

P2 COSSOR VALVE, 1929

Cossor P2 Directly heated battery valve, with Helmet anode.
High Frequency amplifier of 1929.

A0616

DER MOV MARCONI VALVE, 1922

First Dull Emitter valve with a 2 volt heater of 1922. (DER Dull Emitter Receiver) This was a Derivative of the 'R' type with a thoriated tungsten filament of 0.63 Watts ( 1.8 volts 0.35 amps ) which reduced filament power by a factor of 4.
Developed 1st by the Marconi Osram Valve Company.

A0630

S625 MOV VALVE, 1927

Developed by H.J.Round (Captain) for the Marconi Osram Valve Company.
The S625 was one of the worlds first fully screened RF amplifier valve.

A0632

S215 MOV VALVE, 1928

The Marconi Osram Valve Company developed the S215 in 1928.
It was a 2 volt filament screened RF Tetrode, and was the upright version of the S625 See Item A0632.

A0634

MH4 MOV CATKIN VALVE, 1932

The Marconi Osram Valve Company developed the MH4. An indirectly heated Triode, that became the general purpose valve for set makers in the 30's. And was the worlds first all metal valve, the case of this valve (Anode) carried the full HT voltage. See Item A0638 for a Catkin with a cover.

A0637

MS4B MOV CATKIN VALVE, 1933

The Marconi Osram Valve Company Nicknamed this shape as a 'Catkin' A miniature cooled anode tetrode, the idea was to dissipate as much heat as possible from the anode to the air. Inside the can was a metal envelope that was in fact the anode itself, the can was added to prevent the user getting a shock from the anode. This valve is a screened RF Tetrode Frequency Changer.
See Item A0637 for an earlier version.

A0638

3C24 VT204 PHILIPS VALVE, 1938

Philips Transmitter VHF Triode of 1938.

A0607

QQV07-50 MULLARD VALVE, 1964

Mullard QQV07-50 Double Beam Tetrode of 1964.

A0705

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

A0645

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.

A0585

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.

A0584

VT 218 EIMAC VALVE, 1937

Eimac VT218 100 MHz Triode of 1937.

A0656

RK28A RAYTHEON, 1937

Transmitting Pentode of 1937 on paxolin chassis mounting base.

A0588

LEWIS 35T VALVE, 1936

VHF Transmitter Triode of 1936.

A0605

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.

A0590

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.

A0592

4E27/257B HEINTZ AND KAUFMAN VALVE, 1938

Heintz and Kaufmann 4E27 Transmitting Pentode of 1938.

A0658

QV08-100 MULLARD VALVE, 1960

Mullard QV08-100 100 Watt Transmitting Tetrode of 1960.

A0703

QY5-3000A MULLARD VALVE, 1964

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

A0654

HEINTZ AND KAUFMAN GAMMATRON VALVE, 1930's

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

A0606