My assignment in the fall of
1929 was to design and build the television equipment for
use at W9XAP, the companion station for the Chicago Daily
News station, WMAQ. It was to be located on the 25th floor
of the Chicago Daily News Building, on 400 West Madison St.
Multiple cameras were to be used to facilitate the
instantaneous scene changes required for smooth programming.
Two flying-spot scanners were provided, each with a turret
of four projection lenses and a steerable surface-reflecting
mirror to properly position the scanned field. The low
scanner was used for seated persons seated behind a bank of
photo-cells built into the wall. The other scanner projected
its beam at eye height into the studio. The light sources
for the scanners were 30 volt, 30 amp incandescent
projection lamps.
Light pickup for the long shots was by means of two large
photo-cells suspended from ceiling tracks on either side of
the studio. Each one had a separate preamplifier and cable
to the main amplifier rack adjacent to the scanners. The
main amplifier boosted the picture signal and sent it over a
special low capacitance cable to the W9XAP transmitter over
100 feet away. A viewing monitor mounted in the rack
permitted convenient checking of the picture. Switching
between pickups employed relays, pushbuttons and signal
lamps. A special feature automatically blanked out the
picture briefly during lens turret operation.
The W9XAP transmitter was
designed like a commercial broadcast transmitter with a
temperature-controlled quartz crystal to maintain the 2150
kc carrier. Several RF buffer stages amplified the carrier
to drive a 1 KW water-cooled output tube. A similar tube was
used as a series modulator, but this was later changed to a
system using a linear amplifier after the modulator.
A large storage battery on
an insulated platform supplied the RF output tube filament.
The 4000 vdc supply consisted of two double commutator
generators connected in series and mounted on either side of
a large dc motor. The antenna was strung between the two
flag poles on the roof of the building, just above the
transmitter room.
The first official telecast
of W9XAP was on August 27, 1930. Receivers were distributed
to stores in the Chicago area, including Sears Roebuck.
Large crowds assembled to see and hear WMAQ artists perform.
The signal was strong but the "ghost images" caused
disappointment. It seems that ionized layers 50 to 100 miles
up caused the delayed signals, resulting in ghosts. Later,
images from W9XAP were received up to 400 miles away.
One interesting sight-only
program consisted of election returns on the evening of
November 4, 1930. Television programs from W9XAO were
regular enough to be listed in the Daily News. In fact, here
was a two column photo of Marcella Lally in front of the
photo cell bank in the May 7, 1930 issue. She may have been
the first TV performer to be seen and heard simultaneously.
The play, "The Maker of Dreams," was broadcast on the
evening of January 7, 1931, possibly the first sight and
sound dramatization broadcast. [On September 11, 1938, GE
broadcast "The Queen's Messenger," but it did not include
sound.
The transmission of
fingerprints for the police commissioner was also considered
a success. Even ticker-tape stock quotations, delayed 15
minutes were broadcast. Several programs consisting of
cartoons drawn on tape were pulled past the scanner.
