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Valve Collection

Technical Information

Catalogue No: C1869
Category: Vintage and Antique
Object Type: Display Unit
Object Name: Valve Collection
Part No: None
Serial No: None
Manufacturer: Brimar
Year of Manufacture: Unknown
Dimensions: Width (mm): 0
Height (mm): 0
Depth (mm): 0
Weight (g): 0
Location: Main Store

1900s Valve Development
Examples of vacuum valve development in the early 1900s which provided one of the enabling technologies which resulted in the development of the CRT. The other technologies which were necessary for the CRT to become a practical device were phosphor screens, electron optics, and vacuum technology.


The collection of seven vintage valves is mounted on a wooden base each one being identified
The Brimar Valve Collection
The original notes on the item are in italics
1900s Valve Development
Examples of vacuum valve development in the early 1900s which provided one of the enablng technologies which resulted in the development of the CRT. The other technologies which were necessary for the CRT to become a practical device were phosphor screens, electron optics, and vacuum technology.
The valves on this board are described from Left to Right with Flemings on the Left.
Valve 1. Experimental lamp made in 1889 for J. a. Fleming to investigate the ‘Edison effect’.
In October, 1904, John Ambrose Fleming, a British electrical engineer, deinonstrated that a high-frequency alternating current could be rectified, or converted to direct current, by what looked like a dimly glowing incandescent lamp in which a fiat metal plate was supported between the legs of a carbon filament in the form of a single loop. In his master patent, filed the next month. Planing disclosed how his primitive vacuum tube could be used as a signal detector in a wireless telegraph receiver circuit. Since his tube acted like a water valve allowing flow in one direction only, Fleming called it an "oscillation valve.” In describing it to Guglielmo Marconi, in his capacity as technical adviser to Marconi’s WirelessTelegraph Company, Fleming wrote: “This opens up a wide field for work……I have not mentioned this to anyone yet as it may become very useful."
By virtue of many careful experiments extending over two decades Fleming earned the right to be regarded as the inventor of the original electron tube.
Fleming also sent Marconi five of his oscillation valves to be used and tested at Marconi's Poldhu wireless station in Cornwall. The Fleming valve had limited applications and the way in which Marconi's company held the patents meant that few others could use the concept and this significantly limited its uptake.
The next major step in the development of this technology was taken by an American named Lee de Forest with the introduction of his Audion triode valve.

Valve 2. Flemings second design of diode valve produced in 1906
This Valve has a two pin base rather like a UK Lamp. The second electrode surrounds the filament in this version.
Valve 3 The Ediswan version of the ‘R type’.
The R-type valve was one of the early success stories of the thermionic valve or vacuum tube business. It was designed and primarily manufactured in the UK, although some were manufactured outside the UK.
The R valve was a basic directly heated triode and one of the most successful of the early valves and was manufactured by a number of different companies.
Valve 4. The ‘R2 type’ a development of the ‘R type’ but still a ‘soft’ valve, circa 1917.
A low vacuum tube is called a 'Soft' valve, a high vacuum is a 'Hard' Valve.
This has a screw-in base. This was similar in construction to the French type TM valve. The envelope was filled with nitrogen to a pressure of 0.06 mm mercury. The details of the valve were released to a number of manufacturers and the first production of this valve was delivered in June 1917 by the General Electric Company. (GEC Osram)

Valve 5. Development of the ‘R type’ Stem pumped circa 1920
This may be the ‘R7 type’ of R valve which was made around 1920 by the Mullard Radio Valve Company.
Valve 6. Power Output Valve Type B4 introduced in 1923
The B4 was the first dull emitter valve from BTH (The British Thomson-Huston Company) and was first introduced in 1923. BTH claim that the B4 was the first 6 Volt valve in the UK to draw only 0.25 A.
The design of the B4 was for an AF amplifier to drive small loudspeakers. These would not be the moving coil devices of today but probably a horn device powered by an oversize earpiece and being wound with a high impedance coil that was wired directly into the anode circuit of the valve.
The base shell has a central groove and this base shell is typically found on M-OV valves. The Bakelite on the base infill has the BTH logo. This base shell type was in use around 1923-4. http://www.r-type.org/exhib/aaj0003.htm
Marked: BTH Type B4 6V
Valve 7. Short path indirectly heated mains valve made in Manchester by Metro Vickers circa 1927 and sold under the “Cosmos” brand.
This is a triode valve possibly the DE11 type.

Brimar was a major supplier of high-performance CRTs to BAE Systems and Smiths Industries and indeed globally. Their products have been continuously developed over 50 years to keep pace with the demands of a modern Head Up Display.  However,  high-performance CRT’s are still largely made by hand with the glass bulb hand blown. The quantities have never reached a break point for full automation of manufacture, even on the A-7 or F-16 programmes.

The name of Brimar continued to have a long association with the HUD story through the supply of CRTs and interestingly Brimar and Cintel once again became linked as associated companies. 

Brimar finally fell into administration in November 2012, blaming the economic climate and difficult trading conditions. However Dermot Power [A1.3], BDO business restructuring partner and joint administrator of Brimar, was able to announce that: “We are pleased to announce that we have completed the sale of the business of Brimar Limited, with a sale of the vision system display business to Image Precision Limited on 3 May 2013 and the Cathode Ray Tube and Long-Range Thermal Imaging business to BAE Display Technologies Limited on 3 June 2013”.

The CRT is an important component for the Company for its range of Head Up and Helmet Mounted displays and with a large number of systems fielded and requiring long term support it was essential that the supply was protected.  So, the link back to John Logie Baird once again came back into the Company as BAE Display Technologies Limited (DTL). 

The future prospects for CRT sales were looking very thin so after great deliberation, and consultation with the trade unions, BAE Systems announced the  closure of DTL in December 2018. Customers had the opportunity for a ‘Last Time Buy’ of CRTs but in future a solid-state replacement will be offered.

With the closure of the Middleton factory BAE Systems brought a collection of items down to Rochester which include a fine display cabinet showing various modern tubes and assemblies and a valuable collection of historic Cathode Ray Tubes and Valves.


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