The World’s First Factory-Built Transmitters
The station is WWJ in Detroit, a
contemporary to KDKA as one of the country’s first radio stations. We are in
the transmitter room in the Detroit News Building in early 1922. The broadcast
studio is located in a separate room.
from the Detroit News Archives
The rig seen beyond the operator’s desk
is actually the station’s second transmitter; it replaced a primitive DeForest
50 Watt transmitter that the Detroit News used beginning in August of 1920
under the call letters 8MK. (The station was re-licensed as WBL in 1921 and
became WWJ in March of 1922.)
The transmitter seen here, installed in
February 1922, was the world’s first factory-built model, the Western Electric
This mighty 500-Watt unit consisted of
two panels: the RF section and modulator on the left, and the power control
panel on the right, which controlled the two motor generators that provided the
DC energy, located in another room because of their constant noise.
The two big knobs on the front of the
transmitter are marked “Oscillator Tuning” and “Frequency.” Crystal controlled
oscillators were still in the future; these early transmitters were just
free-running high-power oscillators. The antenna capacity was a part of the
oscillator circuit, and so the station’s frequency tended to drift as the wind
blew the hammock-style wire antennas around. Static buildup on the antennas
during wind storms also caused frequent transmitter failures. The result later
that year was the introduction of the 1-B transmitter, which added a third big
“Antenna” knob to control an output coupling transformer.
On the operator’s desk, we see a
wavemeter with its loop antenna, used by the operator to zero-beat the
transmitter to the station’s assigned frequency (360 meters, or 833 kHz). To
its right is a Grebe CR5 receiver and audio amplifier, used for program monitoring
and for the required listening for maritime distress signals during five
minutes each hour. Receiver batteries and antenna knife switches are to the
operator’s right. Just out of view outside the window is a large loop antenna
that fed the receiver. In addition to operating the transmitter and making
station announcements, the operator’s main job was to ride gain on the studio
microphone to keep the transmitter from overmodulating.
Later photos from WWJ show this room
gradually filling up with more equipment, more operators and a more powerful
transmitter. It continued to be used by the station for the next decade.
John Schneider is a lifelong radio
history researcher. Write the author at email@example.com. This is one in a
series of photo features from his collection. Find more under the Columns/Roots
of Radio tabs at radioworld.com.