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Early Picture Tubes

Baird/Rauland Projection CRT

This tube is about 3 feet long. Inside it has a phosphor screen. The rear is designed for high voltage. It is a projection tube, made by Baird in England, in 1939, for their theatre system. Rauland replaced the base sometime later.

Rauland demonstrated a projection system in 1946, but it probably used a different tube (see the bottom of this page).

 

John Logie Baird developed a projection system in 1939 using a very similar tube. Baird demonstrated the system in the U.S. and formed a U.S. subsidiary to market it. In 1942, Rauland bought the subsidiary, and continued developing the technology. Our tube is probably an early Rauland version of the Baird tube.

 

Here is an excerpt from an article about Norman Rauland in Sound and Communications magazine in 2007.

Courtesy of Carl Cox, Vice President & Director of Engineering at Rauland

There are three pins on the base. Two are connected to the filament (inside the first metal sleeve above). The other is connected to that sleeve, probably a control grid. The next metal sleeve is connected by a wire to the phosphor plate in the ball of the tube, which, in turn, is connected to the large connector on the rear of the tube. Our tube has SK 180 printed on the neck, and 80 KV etched near the screen opening.

I have been in touch with Dr. Douglas Brown MPhil PhD (J L Baird and television technology historian), Director of the Strathclyde Science and Technology Forum, University of Strathclyde, Glasgow, Scotland. Dr. Brown has written a book about Baird (Images Across Space), and has done considerable research on John Logie Baird's theatre television system. He provided this blueprint of a 1939 Baird projection tube. Our tube is identical to the drawing.

His conclusions about our tube are:

1. SK180 is the vital clue and tells me that the tube was fabricated at Baird Television Ltd by Dr Constantin Szegho prior to 28th April 1939.

2. I know this as I have a copy of a Baird Television blueprint for 'SK217' dated 28th April 1939 with a filing date of 11th July 1939.

3. The dimensions of SK217 matches  those of SK180,

4. The inside coating of graphite giving it a silver appearance was only on the Baird tubes

5. The Rauland tubes were more cylinderical while the Baird tube was tobacco pipe-shaped and bulbulous.

6. The name RAULAND that appears on the neck of the tube was a later addition and is a statement of ownership, after Rauland took over Baird Inc and hired Dr Szegho. 

7. SK180 (possibly meaning 'Szegho Kinema' tube/version 180)  is a right-hand tube designed for use in a twin theatre projector unit.

The Baird projector which used this tube

Courtesy of Dr. Douglas Brown MPhil PhD (J L Baird and television technology historian)

Rauland projection tube

Courtesy of Dr. Douglas Brown MPhil PhD (J L Baird and television technology historian)