IN THE KFI CAGE
By Newcomb Weisenberger

The KFI 50,000-watt transmitter dominated the second floor of the Buena Park building. Centered in the room was the engineer's desk. Its top was cut to house the large master switch. A small brass railing protected it against accidental operation. Here too was the VU meter to monitor the audio input.

The KFI Transmitter Control Room

The engineer faced a three-sided "U" of metal panels. To his left was the monitoring equipment and the lower stages of the modulator. In front was the metal wall made up of a 200-watt transmitter feeding a 1,000-watt transmitter feeding the 50,000-watt RF amplifier. At his right was the three-phase full-wave rectifier. (17,000 volts DC.) (The two 90 degree, corners were joined by metal doors at 45 degrees.) These doors were interlocked, for safety, to shut down the station, if opened. The operator could read the large meters all along the top of these metal walls. Also he could see through the glassed openings, to the large vacuum tubes lighted by their filaments. Behind this wall the units were open metal frames exposing the various operating components. Many of these were hidden from the operator.

The high voltage and radio frequency connectors, of copper tubing, were run overhead and safely out of reach. One man maintained watch in this room perpetually! Night and day, three shifts, every day. At any moment it might be his duty to re-set the main switch. (This was a bat-handled oil-filled switch that acted like an oversized circuit breaker.) Every 30 minutes he logged the power of the last stage and the frequency deviation from 640 k Hertz.

Every two hours a complete tour of both floors, logged the temperature of bearings and contact of brushes on all rotating equipment and a reading of all meters including Southern California Edison. A second man watched over the first floor full of duplicate pumps, 200 Amp. DC filament generators, 1,000 Volt bias machines and the 510 hp 50 to 60 cycle frequency changer. (So. Cal. Edison's AC was 50 cycles at the time.) The second engineer stood by for breaks and meals. (There was a small kitchen and machine shop adjacent to the transmitter room.)

The transmitter engineer was alert for changes in sound, power surges, arc-overs, the odor of overheated windings and failing parts. He was ready to extinguish a sustained arc by opening the high voltage switch. (A small animal, dirt, movement of parts or wiring and strong surges of power can cause an arc-over.) When conditions are right, the arc will continue to burn until power is removed. The heat of the arc can change some insulators into carbonized conductors. The operator may hear the arc roar and see the flash but not know where it was. A bad burn might take us off the air until repaired.

On occasion, it was necessary for someone to observe the arc-over from the inside of the transmitter. This happened to me! I am inside the transmitter, sitting cross-legged on the floor, both hands are in my lap, positioned out of high-voltage reach. The other engineer calls, "Are you ready?" The doors are closed and full power turned on. I remain motionless in the dark, watching for the arc hidden in the transmitter's insides. My head has a short dialogue with my body. My body says, "Get out of here! This no place to be." My head says, "Don't panic, you are safe where you are. Don't stumble into trouble" The big switch slams shut, I see the arc! It is between the open plates of the large, (four foot) air dielectric, condenser.

An Air-Dielectric Capacitor in the KFI Transmistter

Immediately the engineer pulls the high voltage switch. The arc is dead. Its roar is still in my ears. The door swings open; I can breathe easier now, and step outside, just because I can!

During maintenance, when KFI was off the air, engineers searched for these burned areas, tightened connections, cleaned, polished insulators, changed filters, tested and installed tubes, repaired contacts on the large oil filled switches. The more interruptions during the week, the more the contacts were damaged.

Note: To this date, no KFI transmitter engineer has had a serious work related injury. We trusted each other with our lives. These men were my friends.