KPO 50kW Transmitter Building
The KPO transmitter building was built under contract to NBC by General Electric in 1932,
along with the transmitter itself.
First Floor: In the main room were located the filament and bias motor generator sets, their
associated switching and starting equipment, and the battery charging generator and control
panel. Other rooms included the main building power service, filament circuit filter reactors,
the battery reactor, intermediate rectifier plate transformer, final amplifier plate transformer,
voltage rectifier, rectifier filter reactor, water cooling equipment, and the batteries which provided
the plate and filament supplies for the tubes of the audio equipment. Also on the first floor were
a kitchen, garage, and spare parts storage.
Second Floor: The main room contained the transmitter itself, along with the transmitter operator's
desk. Another room contained the speech amplifier rack and remote control equipment. Also on
the second floor were the engineer's living quarters, office, shop and storage room.
Outdoors: At the rear of the building was a large concrete pedestal which held the primary three
phase AC service transformers and the giant radiator blower, which was the primary cooling system
for the distilled water that cooled the transmitter tubes. A water spray pond provided backup cooling,
and its water was used to cool the heated distilled water through a heat exchanger.
Two engineers were required on duty at all times to operate the transmitter. One engineer watched
the transmitter, while the other engineer manned the speech amplifier equipment and adjusted the
audio level for proper modulation of the transmitter. These engineers were also occupied with a busy
schedule of maintenance.
This building continues in use today as the transmitter site for KNBR, today's descendant of KPO.
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All articles copyright © 1997-2006 by John F. Schneider. All rights reserved.
Reprinted with the generous permission of the author.