Television Experimenter'
TeKaDe History page 1
TeKaDe continues to engage in attempts to
develop low cost mechanical television receivers
and has released these two photos shown here
and below, of a model for year 1935.

The photo here shows the complete receiver in its
cabinet. It measures about 12 inches square and
is about 18 inches deep. The cabinet is all wood
except for the glass window on the front, through
which one sees the television image. The
shipping weight on this receiver is about 25

The second photo shows approximately where
some of the various significant parts are located.
The drawing shows there is a support deck about
center from top to bottom and from front to back,
with the optical parts located above and the
electrical parts mounted below. Since this
drawing and its associated comments are written
in pencil, it must be assumed that this is not a
"released" drawing and that the actual
components and their placement may differ from
the actual finished or completed item.
The support deck is held in place by six
vertical risers, off of the 3/4" base board.
Later on, the risers will also support the
cabinet cover. The support deck will be
installed in such a manner that it can be
removed at a later time if desired.
One of the first components to be considered are the motor and the mirror screw. The motor must be a four or
six pole synchronous alternating current motor and it is normally supplied with the mirror screw as a package.
A synchronous motor is required whenever power line synchronization is used, as is the common practice with
mirror screws. The motor will be held in a wooden saddle that will allow the motor body to be manually rotated
approximately 90 degrees. This saddle must also allow cooling air to pass from beneath it and into the cooling
ports of the motor end plate that mates with air passages in the motor end caps. A metal arm is bolted to the
upper end bell of the motor, for the purpose of rotating the motor body a few degrees to align the image start
point. Notice in the photo on the left, the motor is held captive by the wood saddle at the bottom and the
aluminum clamp at the top. The body is able turn, but with some resistance due to pressure, so as to not be
"free to move". In the photo below, the adjustment arm has been added, the small end of which passes
through a 2 inch long slot in the side panel of the cabinet.
This photo shows the motor and its phasing
capacitor. The motor wires need to be left long
enough so as to allow the rotation of the motor
body, when setting the position of the image
lines starting point. Also notice that the saddle is
held in place by 4 screws that pass through the
baseplate into 4 "T-nuts"
This photo gives another view of the motor
area. The additional wiring seen here is the AC
input connector and video and sound input
German Television on June 21, 1932!

By 1932, most television development activities in the United States, were now directed towards receivers using
a cathode ray tube. This was also true in Great Britain but to a much lesser extent in Germany.

At the 1932 Berlin Radio Exhibition, in addition to radios, there were also displays and demonstrations of both
mechanical and cathode ray tube television receivers.
Telefuken demonstrated two sets, one was a 48 line mirror drum type, equipped with a Kerr Cell providing a 16"
X 20" B/W picture. The pictures were judged to be very good, bright and with a slight amount of flicker. They also
demonstrated a cathode ray tube set, providing images of 90 lines at 25 images per second. These images had a
pale green color, measured 4.8" X 3.6" and were judged to be excellent.

Loewe demonstrated a 90 line cathode ray tube set, operating at 25 pictures per second. The images measured
4.8" X 3.6". In this case, the picture had a distinct blue color. Those who saw it, judged the picture to be very
good to excellent.

Fernseh A.G. Their first of three entries was a 120 line at 25 frames per second, disk type receiver equipped with
a new type of Sodium lamp. The 2.8" X 3.6" picture produced was a pale yellow color. They used a similar lamp
with a 90 line disk type of receiver and it too was operating at 25 frames per second. The picture size on this
second set was 6.4" X 4.8" and the picture quality on both was judged to be very good. A third working entry
from Fernseh A.G., was a 90 line mirror screw operating at 25 frames per second, with an image size of 6.4" X
4.8". A neon lamp was used to illuminate the screw and the image was pink in color. The image detail was
excellent, but the intensity was judged only as good.

There was also a fourth entry shown, but it was not working. It was a 90 line mirror screw exactly like their
other, except that it was to be illuminated by a Sodium lamp.

H.H.I. (Heinrich Hertz Institute for Wave Propagation) demonstrated one 90 line mirror screw providing 25 frames
per second. They used a new H.F. Mercury/Argon lamp that produced a blue picture measuring 5.2" X 6.0" and
judged very good to excellent.

R.P.Z. (German Post Office) They demonstrated one cathode ray type receiver, another disk type with a sodium
lamp and and a third using a mirror screw, also with a sodium lamp. All three provided 25 pictures per second.
The picture on the cathode ray tube set was blue and it looked to be yellow on the other two. Picture quality on
these three sets were judged to be very good.

TeKaDe Demonstrated three different size sets, all with 90 line mirror screws and using Neon lamps for
illumination. The smallest set produced a 2.4" X 2.8" picture. The next was 5.2" X 6.0" and the largest was 12.0"
X 14.4". All three provided 25 pink colored frames per second and were judged to be good to very good image

There were no television sets offered for sale at the Berlin show for 1932.

Now, let's jump ahead two or three years, 1934-1935.

Problems noted in the 1932 report have for the most part addressed, solutions developed and incorporated.
Picture colors are now a good B/W or at least nearly so. Synchronizing has improved and return beam blanking
on cathode ray tubes has lead to much improved picture quality. Cathode ray tube life was greatly improved.

With the exception of TeKaDe, all of the potential major television manufacturers have abandoned mechanical
scanners of any sort. (It must be pointed out, that TeKaDe also has a major effort ongoing to develop television
receivers using cathode ray tubes).
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