Lectrosonics FM870 - Manual (Page 3)

GENERAL TECHNICAL DESCRIPTION
The FM-AV4 Portable Wireless Sound System consists of an FM870 combination wireless
receiver/amplifier/speaker with a rechargeable battery pack, an M170 belt-pack transmitter and a
microphone. Optional microphones, transmitters and accessories are available. These items will be
discussed elsewhere in this manual.
The FM-AV4 features a VHF high band wireless microphone system with excellent operating range,
freedom from "dropouts" and interference from other radio transmissions. The built-in receiver provides
high selectivity and sensitivity with an automatic squelch circuit which requires no adjustment by the user.
The M170 belt-pack transmitter uses the microphone cord as the antenna which eliminates the dangling
wire antenna found on many other transmitters. The transmitter features a gain adjustment to perfectly
match your voice with the microphone.
The FM870 receiver/amplifier offers inputs and outputs to accommodate virtually any application. In
addition to the wireless, there is an auxiliary microphone input for dynamic microphones, a balanced,
microphone level audio output, and both "line in" and "line out" jacks for external tape recorders. This
allows the FM-AV4 to interface with other sound systems, video taping equipment or any type of "house"
sound system. This versatility lets you use the wireless microphone, a hard-wired microphone, a tape
recorder and the house sound system all at the same time.
The FM870 is powered by built-in rechargeable batteries and will easily operate for over 12 hours after an
overnight charge. The sound output will cover an audience of several hundred.
RECHARGEABLE BATTERIES
The battery pack in the FM870 is charged by plugging the supplied CH-40 charger into the jack labeled
CH-40 CHARGER INPUT on the control panel and moving the POWER switch to the CHARGE position.
Connect the charger into a standard 110 Volt AC outlet. The red POWER lamp beneath the switch will light
as long as the batteries are charging. There is no way to tell when the batteries are fully charged. To be
on the safe side, charge the battery 12-15 hours to be sure. The batteries should be charged after using
the system. You may leave the charger plugged in with no danger of damage to the system. They cannot
be overcharged. In fact, we recommend charging the system whenever it is not in use, then the system
will always be "ready to go".
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