NATIONAL UNION Monatron / Monotron 2203
Monoscope Tube
Tube générateur de mire
Monoskop-Röhre zur Testbilderzeugung
Early in 1938 National Union announced a device
called a Monotron (also called a Monoscope)
designed to generate a television image for those
doing television receiver research, or those who
wanted to learn how to service television sets, or
those who needed to tweak up focus and linearity
adjustments on a set. “Why,” might you ask, “didn’t
people just use a test pattern broadcast by a television
station?” There was very little TV broadcasting
taking place at the time, and even if a station had a
test pattern, it might not be on the air at the time you
wanted to check out a set.
National Union’s Monotron resembled a 3-inch CRT
of the era, and used the same electron gun as National
Union’s 3-inch CRT type 2003. Communications for
April 1938 (p. 26) stated that “In the Monotron, a
metallic signal plate takes the place of the usual
fluorescent screen. Upon this metal plate and facing
the beam of electrons within the tube is printed a test
pattern. This test pattern is fixed, and may not be
varied in so far as any one tube is concerned. The test
pattern, however, may be different for each tube.”
As the electron beam scanned the image, the
secondary electrons were collected by a suitable
electrode. The secondary electron stream intensity
varied depending on whether the beam impinged on
the metal plate or the special ink. The resulting image
signal could serve as a test pattern.
Longueur • Length • Länge : 30,5 cm • 1' 1" 2/10
Diamètre • Diameter • Durchmesser : 7,5 cm • 3" 1/2
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