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4 inch Monochrome CRT

Technical Information

Catalogue No: C1867
Category: Vintage and Antique
Object Type: Display Unit
Object Name: 4 inch Monochrome CRT
Part No: 0
Serial No: 0
Manufacturer: Ediswan
Division:
Platform(s):
Year of Manufacture: circa 1930
Dimensions: Width (mm): 100
Height (mm): 0
Depth (mm): 0
Weight (g): 0
Location: Unknown
Inscription(s):

None

Notes:

This is a 4” gas focussed monochrome CRT 12” long electrostatic tube.The CRT was the first commercial tube from Ediswan called the 'Type B Tube' and was released in 1930 following the experimental "A" tube. The base is a 4 Pin side contact type.
The CRT was developed for use in the early electronic television and an article by K D Rogers in Popular Wireless of May 27th 1933 shows a similar CRT being used in an experimental Television receiver
The earliest CRTs were 'gas-focussed' - a very small amount of gas was deliberately left inside the tube, and this assisted the focussing of the electron beam. Such tubes were not very stable, or long-lived, which is why the 'hard vacuum' tube was developed.

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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