AMATEUR COLOR TELEVISION

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP81-00120R000100020029-4
• Release Decision: RIFPUB
• Original Classification: K
• Document Page Count: 5
• Document Creation Date: December 20, 2016
• Document Release Date: December 4, 2003
• Sequence Number: 29
• Content Type: OPEN

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Approved For Release 2007/09/21 : CIA-RDP81-0012OR000100020029-4
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A New Ficid
for the
Experimenter
Over-all view of the color television
system. The bottom unit on the left is
the flying spot scanner which was made
from a discarded TV set. The color
slide to be transmitted is fastened to
the face of the cathode-ray tube and
is visible just beneath the upper chassis.
In the center of the picture is the photo-
cell chassis with three photomultiplier tubes equipped
with red, blue and green filters facing the scanner. On
the right is the sync and blanking generator. This, too, was
made from a salvaged TV receiver, and is also part of
the author's black and white television system. The
coaxial cables from the photocell chassis carry the red,
blue and green channels to the color unit, the upper
chassis on the left. This is the heart of the system and
contains a matrix for converting the three color signals
to standard black and white, "I" and "Q" signals, plus
the 3.58-Mc. color carrier oscillator, the color modulators
and the burstsignal generator.
I7H amateur television on its way to be-
coming a popular phase of ham radio, it
should be done in color. Since color TV has been
confined primarily to commercial broadcast use,
a great deal of planning and gathering of informa-
tion was necessary before undertaking such a
project. Such questions as what type pickup
source would be desirable, could good color
quality be obtained, what types of color filters
should be used, and could junk-box parts be
made to work had to be answered. After studying
all of the facts and drawing up some circuits
that would be satisfactory for amateur purposes,
it was decided that it would be practical to go
ahead with the project. Fig. 1 shows a block
diagram of the system that was finally decided
on and constructed.
Type of Pickup
Cost was a prime factor, and since this was an
experimental project I decided to use the "flying
spot scanner" type of pickup to transmit color
pictures put on glass plates about 3% X 4 inches.
These slides have been made with water colors,
drawing inks, colored cellophane and trans-
parency film. Briefly, the flying spot scanner
depends upon a light source that is capable of
scanning the color slide at the proper rate. The
light at any one instant will depend on the den-
sity of the slide at that point.. If the slide is in
color the light will also be filtered as it passes
through the slide.
Assume now that the beam of light is passing
through a red portion of the color slide- This
* Box 8(17, Ilakot, City, Nebrn.cka.
September 1960
Arniteur Color
Te1'evis9*0 a
simply means that the red dye in the slide absorbs
all the colors except red. Therefore, this is the
only color that will pass through the slide at this
instant. If a photocell is now placed is front of
the slide with a filter in front of it an that only
red light will be allowed to pass through, then
a voltage that is proportional to the light passing
through the slide at that point will be developed
by the cell. Now, if we have a second cell with a
filter that will pass only blue light in front of it,
and a third cell with a green filter, we will be
able to produce every color of the rainbow, in-
cluding white, simply by proper mixing of the
three basic colors.
Those who feel that regular black and
white TV is on the far fringe of Itarn
experintentatiora, had better catch
their breath. ITOKYQ has built a color
television systern which transmits
slide pictures and drawings with ex-
cellent quality. So far as we know,
this is the first antatear color TV to
be put on, the air, at least in the United
States. The signal is very sintilar to
the NTSC standard for cottwnercial
broadcasters and can be viewed on a
standard color .set with a 4211-11c. con-
carter. It is also contpa-ti.ble witit reg-
ular black and white receivers. By
using junk-box parts and sections of
t ice-awav TV sets rite author
o
g
tt
>> kent thr cost of rite system to $175.
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 Approved For Release 2007/09/21 : CIA-RDP81-0012OR000100020029-4
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For example, assume it is desired to produce
yellow. Red and green when mixed in the proper
proportion will produce this color. Therefore as
the light beam is passing through a yellow portion
of the slide, the red cell will see red information
and the green cell will see green information.
When these two separate signals are recombined,
the original yellow will be reproduced. Let's
take one more example. If we want to reproduce
white light, which is actually a mixture of all
colors, it will be found that the red photocell will
see about 30 per cent of the light, the blue cell
will see about 11 per cent, and the green cell will
see about 59 per cent. When these three signals
are -added together, the original white will be
reproduced.
The amount of light actually reaching the
photocells after passing through the color slide
and the selective filters is very small, so sensitive
photomultiplier tubes were used. The green and
blue channels use 931-As and the red channel
uses a IP22. These photocells are presently on
the surplus market for about 85 each. The filters
that were used in front of the red, blue arid green
photocells were Kodak Wratten filters Nos. 25,
478, and 58, respectively. Each of the photocells
is followed by a three-stage video amplifier em-
ploying GAK5s. This unit was built on it separate
chassis along with its own electronically-regulated
power supply.
Light Source
Readily-available used television' receivers at
iVeit h-~ pricurneIvc re pro , em oT a scaurung
iglrt source. In this instance, an old RCA IKCS
28 chassis was obtained for $5. All of its front-end
tubes were removed, ]caving onll the sync,
video amplifier and deflection circuits intact.
Arno nee rectifier tube was ~icT
reL
l rri pun;ll7'l with
the one that was already in the set, since it was
desired to use this power supply to run the re-
mainder of the color unit. Provisions were also
made to feed in_ Wanking au s r ulse~ta.cnu-
trol thLesca nrn
For the light, it 5AXPI picture tube was used.
This is it TV serviceman's 5-inch substitution
type tube. When selecting a tube to be used for
color television, it must always be kept in mind
that the light transmitted by the tube must have
sufficient amounts of the three basic colors. If
this condition is not met it will be impossible to
obtain a satisfactory signal on all colors. Red is
the hardest color to reproduce from the stand-
point of both the photocell and the light source
since each is down in output at this frequency.
Matrix
The real problem is still to come. The red, blue
and green signals must now be prepared in such
a manner that all their information can be put on
one carrier and also produce a signal which is
compatible with standard black and white re-
ceivers. This is the job of the matrix. Its first
function is to produce a black arid white signal
from the three color signals. This is simply a
matter of mixing the color signals together in the
right proportions. The black and white signal
will also be used in color reception as a mixing
signal.
By properly adding and subtracting the. red,
Close-up of the photocell pickup unit showing the end
which normally faces the scanner. The red, blue and green
photomultiplier tubes are mounted front and center with
their respective color filters wrapped around them. The
gain controls on the front panel are for balancing the
three channels. Behind the photomultiplier tubes are the
red, blue and green three-stage video preamplifiers, and
at the rear of the chassis is an electronically-regulated
power supply. The coaxial cables on the right carry the
three color signals lo the matrix.
QST, for
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 Approved For Release 2007/09/21 : CIA-RDP81-0012OR000100020029-4
And here (don't laugh, now!) is the transmitter. The In-
verted socket at the right holds a 12AT7 parallel line
oscillator for 420 Me. Shown above the chassis are ilia
plate and cathode lines and the heater r.f. chokes. On the
left is a 6CL6 modulator. It and the 12AT7 are connected
in series across the plate supply, and video drive is applied
to the 6CL6 grid. WCKYQ admits the irony of such a
simple rig for so complex a system, but points out that
TV signals are wideband and that the little 5.wattor does
fine for local work. A 420-Mc. converter and standard
color (or black and white) set are used for reception
blue, and green signals electronically, all the in-
formation they contain can be condensed into
two signals if the black and white signal is prop-
erly mixed with these two signals at the receiver.
The two new signals that take the place of the
red, blue and green information are called "I"
and "Q.''
Now we can make use of a very special typo of
modulation called "quadrature modulation."
This is a system whereby two signals can modu-
late one carrier by making one signal always lag
behind the other signal by 90 degrees. The color
.modulators operate on the standard color fre-
quency of approximately 3.58 islc. and are of the
balanced-modulator type. Effectively, we put all
the color information on a single carrier and then
suppress the carrier so that we are sending all
the color information by d.s.b. Next, we mix this
color signal with our black and white signal and
with the standard sync pulses.
Sync and Blanking
Another ea L TV receive we obtained to
generate the, svne pulses This receiver Was- left
intact an is ac iuFtcd to receive a local station.
The s nnc cant then be taken from the sync circuit
in the receiver without an additional et ui meat
being re( utrec . y obtaining the sync in this
manner a superior pulse can be had with the
minimum of cost. The blanking generator is built
as a subehassis on this same unit. It is a group of
multivibrators and clippers which effectively
produce a pulse that will turn out the light source
during the retrace period of the electron beam.
pfhic month
September 1935
The editorial 25 years ago was a plea to amateura
to cooperate in cutting down QllM by three simple meth-
ode: using the proper bands to'avoid jamming DX with
local rats-chewing, trimming power to just that necessary
for the Q130 in progress, and ceasing to teat on radiating
antennas, using dummy antennas instead.
September 1960
The only thing left now is to produce a pulse
which will initiate a reference signal for the color
receiver to lock on so that the proper colors will
be reproduced. This signal is called a burst signal
and is sent only during the period of time when
no picture information is being transmitted.
By making good use of the junk box the com-
plete project cost a total of about 5175. The
results have been very satisfactory. Colors are
true and brilliant. All colors have been faithfully
reproduced, including some of the hardest, flesh
tones.
There is it great deal of fun to be had in explor-
ing this now phase of amateur radio, and I am
sure that we will begin to hear a considerable
amount from now on about experiments in ama-
teur color television. Unlimited ideas and meth-
ods are waiting to be tried out, and many systems
like mine can be built out of readily-available
parts. There are many different ways of produc-
ing color TV and this is only one of them. So let's
go color - there's nothing quite like it in ama-
teur radio. q T-
Note: Practical circuit dinrrams have been left out of this
article, intentionally. Anyone experimenting with rotor TV
would havo to acquire enough knowledge of the subject to
devise his own, based on current commercial practice and
standards if regular receivers are to be used. For more in-
formation, consult texts much as Intredttetion to Color TV,
grid Edition by Kaufman and Thomas, published by Rider.
- Editor.
The magazine served a pot pourri of technical fare
inchtding articles on Plato tnorbtlation of pentodes .. .
an all-purpose s.s. mnperhet with turret-type automatic
coil changing ... it new type u.1,.f, transmitter
a frequency-Lock multi-vidor .. a fh xible e,c.-controlled
transmitter ... Plus technical topics and three pages of
hints for the experimenter.
The seventh international DX contest was hailed
no "the greatest in the history of amateur radio." The win-
der was W351 who rolled up 40,503 points in cnntacting
50 countries on nil continents. "Booth-takincll" nail QST.
. Y'ho third tumual Field Ilay won boiled as beat Yet
- the United Radio Amateur Club of Wilmington, Calif.
took top honors with 1116 points.
15
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May 14, 1963
Filed Sept. 9. 1960
I6~
R. E. GRAHAM
TELEWRITING APPARATUS
3,089,9+18
INVENTOR
R. E. GRAHAM
A7'TORN
Approved For Release 2007/09/21 : CIA-RDP81-0012OR000100020029-4
 Approved For Release 2007/09/21 : CIA-RDP81-0012OR000100020029-4
May 14, 1963
Filed Sept. 9. 1960
FIG. 2
R. E. GRAHAM 3,089,918
TELEWRITING APPARATUS
HORIZONTAL
DEFLECTION
a COS cut
r
TRACKING UNIT
'OUT OF CONTACT' V 'Y'.
INVENTOR
R. E. GRAHAM
ATTORNEY
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