The original monoscope tube dates back to the 1930's when RCA first made
its 1898 a 3" diameter electrostatic deflected tube, looking much like
any other 3" inch CRT. Except for the pin in the center of the screen.
It produced a video signal of a 'girls head' when its internal target
plate was scanned. Then came the 1899 a 5" diameter magnetically
deflected tube which produced the 'Indian head' test pattern that many
television stations would broadcast when they ceased their regular
programming for the day, usually around one, or two A.M. I myself, as
I'm sure there must be others here as well, are old enough to remember
seeing this Indian head test pattern being broadcast late at night.
Eventually the 1899 became customizable with just about anything that a
station would want, circles to be used for linearity, height, and
centering adjustments, wedges for resolution and video bandwidth
measurements, plus the stations call sign. The 1899 was replaced by the
2F21 about the mid 40's. These monoscope tubes and their supporting
vacuum tube electronics were called monoscope cameras. Regular
televisions cameras were not used for the purpose of transmitting the
test pattern for fear of burn in on the expensive, image orthicon camera
tubes, and unnecessary added hours of wear and tear. RCA also made a
1698 2" diameter 'character generator' monoscope, (similar to the
Raytheon CK1414 being discussed here,) primarily used by the U.S. army
during the 1950's. For those of you who are curious enough to see a good
pic of the RCA TK-1A 'monoscope camera', and it's 2F21 monoscope tube,
plus some reading material, you can go here,
http://www.chalkhillcom.com/museum/RCA2.htm I have these tubes as
part of my tube collection, except for the 1899. Hope that all enjoy
the reading, Ira.
On 2/14/2020 3:54 PM, Mac Doktor wrote:
On Feb 14, 2020, at 2:11 PM, Toby Thain <[email protected]> wrote:
Thanks very much for the suggestion! Even the glass etching ability
sounds quite useful for other purposes. (Tangent: I wonder if that could
be used for edgelit projects...)
Also a very effective way to give an expensive brass model locomotive enough
"tooth" on the surface for the paint to stick permanently. Pickling is always a
fall-back.
By the way, what is a "Monoscope"? I've never heard the term before.
Here's the brochure:
http://www.frank.mif.pg.gda.pl/other/Raytheon/Raytheon_symbolray_an.pdf
And @TubeTimeUS got one working:
http://tubetime.us/index.php/2018/06/04/a-vacuum-tube-rom/
I have a couple of these. $15 apiece at a hamfest. I had no idea what they were
but they were too cool to pass up. It took me several minutes to figure out
what they were after I got home. I finally looked in at just the right angle
and as soon as I saw some letters the lights came on.
I think both have leaked, unfortunately. Really did have me going for about
five minutes.
Terry Bowman, KA4HJH
"The Mac Doctor"
https://www.astarcloseup.com/
“The book said something astonishing, a very big thought.
It said that the stars were suns, only very far away.
The Sun was a star, but close up.”—Carl Sagan, Cosmos, 1980
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