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The first sub-miniature tube WE 215A around 1920 (front row)
Miniaturization of parts started back in the early years of vacuum tube development as AT and T wanted to make more compact telephone equipment. The wars speed up development and performance of these small tubes and then during peace time these advances were put into industrial and consumer applications. Raytheon was heavily involved in the development of these tubes for the war effort, resulting in important applications such as the proximity fuze and compact radio equipment and hearing aids during the post war. Miniature tubes began before 1920 with the design of the Western Electric 215A and then later in the 1930's with the Acorn Tube and then the late 1930's real subminiature tubes were developed for the military and practical electronic hearing aids. Basically these tubes are roughly less than 12 mm diameter and a height no more than 50 mm high.
Comparison of pentagrid converters OCTAL, MINIATURE and SUB-MINIATURE
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The ACORN Tube (1930's)
The military was in need to have vacuum tubes that could operate at higher frequencies and yet be used in compact applications. The acorn tube was developed. Although it was a short tube the body diameter was similar to miniature tubes.
TOP ROW: 6F4 and 9004BOTTOM: 954, 955 and 956RIGHT: typical mounting socket
TOP ROW: 6F4 and 9004BOTTOM: 954, 955 and 956RIGHT: typical mounting socket
Peanut Tubes (1940-1950s)
Originally developed for military applications such as the proximity fuze where low power and compactness was needed. Raytheon was a leading developer of these compact tubes. After WW2 they found use in hearing aids and miniature portable radios before transistors became practical and produced in large quantities.INDUSTRIAL TYPE EXAMPLES:
used in oscilloscopes and early transistor portable tv's like Philco Safari. Often connected with other 5642's in a voltage doubler or tripler configuration
Comparison of the peanut tube 5642 and the miniature 1V2High Voltage Rectifiers
Leads are in-line fashion and can be soldered to a terminal or in-line socket.
Left to Right
<<<<5977 Sylvania5902 Sylvania5896 Sylvania5718 Sylvania5397 Raytheon
5642 High Voltage Rectifier. Puts out about 900 Volts.
<<<<<<CK5702 RaytheonCK5703 Raytheon5829 Raytheon5784 Raytheon
HEARING AID TUBES
Before WW2, Raytheon was interested in making sub-miniature tubes for consumer products such as radios and hearing aids. In the late 1930's and until the end of WW2, hearing aids were clumsy, took time to setup and were difficult to conceal. Low power peanut tubes that ran on small batteries like the ones below, had to wait until after WW2. These tubes made hearing aids, clip to a belt and fit in a purse or pocket.
SUB-MINIATURE TUBES for RADIO APPLICATIONS
ABOVE: Raytheon 2E series (late 1940's). These tubes were designed for the first compact radio that can fit in the pocket, the Belmont Boulevard in 1947. These tubes were the 2E32, 2E35, 2E36, 2E41 and 2E42. These tubes have the more common leads in-line and require a 2 volt filament source. NOTE the 2E32 on the left has a sprayed shield.
SUB-MINIATURE MAGIC EYE TUBES
LEFT: Philips DM70RIGHT: Amperex DM160
Circular Pinout Subminiature Tubes
Shown are the 1T6, 1E8 and 1AD5. A fourth tube was the 1AC5. This tube style was not very commonly used
Top to Bottom:Raytheon CK526, CK512 and CK537
Examples of 1950's, 1V6, 1AG4 and 1AH4 with the sprayed on shield. These were more widely used than the Raytheon 2E series probably because the filaments can operate from a standard 1.5 V A Battery. These feature in-line leads.
Philips and Amperex designed some peanut tube magic eye indicator tubes. The Philips produces and exclamation mark type of indication while the Amperex shows a slotted scale.
Sub-miniature tubes for radio set that have leads in a circular format and require a sub-miniature 8 pin socket.
Leads are in a circular position, require subminiature 8 pin round socket.
RCA 7586 >>>>>
CERAMIC SUBMINIATURE TUBES (1960s)
RCA Invents the NuvistorThis is the size of a thimble. Use for high frequency RF amplifiers in both consumer and industrial equipment. The invention of the Field Effect Transistor finally replaced it in the late 1960's
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Planar Triodes for Industrial >>>>>>Applications. These are about half the height of the Nuvistor. Very high frequency response.
Type 7071, The top gold contact is the plate, gold ring below it is the grid and the bottom buttons are the filament connections
Typical shipping box for peanut tubes. The sleeve with tube is inserted diagonally to isolate the tube from the box surface.
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