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4FNG45

 
    
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The 4FNG45 is a high resolution television picture tube with an unusual flat screen construction, where the screen, unlike in conventional tubes, is viewed from the same side as is scanned by the illuminating electron beam. This is a much more efficient arrangement than the conventional approach of viewing through the thick faceplate. The screen is inclined at a slight angle towards the top like a shovel and viewed through the flat face plate on the front of the tube.
This tube is representative of an interesting group of flat screen tubes which find a variety of uses in small portable video, CCTV and television applications. A smaller version of this tube with a two inch diagonal screen size was used in the well known Sony Watchman pocket television receivers. Various manufacturers including Matsushita produce this style of tube in sizes from 2 inches to nine inches across the screen diagonal. The range also included a six inch colour version using a single gun and beam-indexing.
This particular tube is commonly used in CCTV door entry monitors and has a screen size of approximately 4 inches across the diagonal.
The EHT requirement is about 5.5 kV. Apart from the unconventional flat design and layout of the phosphor screen, the electron gun, which utilises electrostatic focusing and magnetic deflection, is fairly conventional for a small CRT of this size.
The rear of the display section. The magnetic deflection coils are at the bottom of the image.
Visible in the foreground is the recessed EHT connector. This is on the base of the screen section and on the left of the picture. The rest of the image is of the deflection assembly and base.
The optically flat and pure faceplate with curved screen on the back plate.
The side window envelope is 13 mm in diameter, and excluding the base pins is 183 mm tall. The screen section is 100 mm x 91 mm and has an optically flat faceplate.
Reference: Jeremy Skertchly.

 

Updated June 21, 2013.
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