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Most bugging is done with simple apparatus, since the tiny transmitters usually have to be abandoned on the job. The smallest bug in common use is about one inch square, and it must be clipped to a metal object or trail a few feet of wire to serve as an antenna. Its range may be a few hundred feet. In such areas as residential Beverly Hills, where rooms are hard to rent and cars cannot be parked on the streets at night, the electronic sleuth buries a brick-size repeater in the victim's yard, threading its antenna wire into a bush. The repeater picks up the weak signal from a bug in the victim's house and rebroadcasts it in sufficient volume to be heard beyond the restricted area.
Security Kit. The private ear can buy a "security kit" for about $300. Mosler Research Products Inc. of Danbury, Conn., which claims half the industry's legitimate sales, packs its sets into handsome, standard-size briefcases. Typical contents:
> An ultrasensitive battery-operated radio receiver with earphones and connections for tape recorder.
> A small audio amplifier with loudspeaker.
> An induction coil, two inches long and three-quarters of an inch in diameter, that can be set beside the wire to tap a telephone.
> A radio transmitter that slips easily into the jacket pocket or handbag, transmits nearby voices to a receiver three blocks away.
> A microphone embedded in a bite-size rubber pad (1½ inches square, one-quarter inch thick) that can be carried in the investigator's palm, attached to an amplifier in his coat pocket; when pressed against a phone booth or a door, it relays the action through an earplug that looks like part of a hearing aid. Hotel dicks love it.
Ears in Cigarettes. Mosler Vice President Ralph V. Ward believes that the best all-purpose bug is a "three-wire tap": a small transmitter that can be fitted in less than a minute into the base of a telephone. When clipped to the proper terminals, it picks up every word spoken both ways over the telephone, monitors ordinary conversations in the room when the phone is not in use. It transmits what it hears by radio; powered by the telephone wires, it works indefinitely. A device at the receiving end translates dialing clicks into the telephone numbers that have been called.
To advance the art, Hal Lipset, a seasoned San Francisco private eye, maintains a laboratory behind a false warehouse front where his eavesdropping "genius," Ralph Bertsche, works out new gimmicks such as a high-powered bug that fits into a pack of filter-tip cigarettes. It is padded to feel soft and shows the ends of real cigarettes to reassure a suspicious businessman or divorce-prone spouse—provided he doesn't ask for a smoke. Bertsche believes that bugs in time may be no bigger than a pencil eraser, recorders as small as a cigarette lighter.*
While miniaturization is now limited by the battery, which must be big enough for adequate power and duration, Bertsche believes that nuclear-energy sources may solve even this difficulty. Already in hand are means to switch off a bug by radio from a distance to save its battery during dull periods. Another battery-sparing device works by sensing the electrical capacity of the human body; it can turn on a bug when people come into a room or climb into a bed.