Lectrosonics DR185 - Manual (Page 6)

ANTENNA USE AND PLACEMENT
There are two antennas included with this receiver. One is a telescoping whip that connects to either terminal on the
rear panel of the DR185 receiver. The other antenna is a coaxial type for use away from the receiver. This remote
coaxial antenna should be positioned so that the stripped end of the coaxial cable is at least 4 or 5 feet (1/2 wave­
length or more) away from the whip antenna. This will insure the maximum benefit of the diversity circuitry.
Position the antennas so that they are not within 3 or 4 feet of large metal surfaces. If this is not possible, try to
position the antennas so that they are as far away from the metal surface as is practical. It is also good to position the
receiver so that there is a direct “line of sight” between the transmitter and the receiver antenna. In situations where
the operating range is less than about 50 feet, the antenna positioning is much less critical.
A wireless transmitter sends a radio signal out in all directions. This signal will often bounce off nearby walls, ceilings,
etc. and a strong reflection can arrive at the receiver antenna along with the direct signal. If the direct and reflected
signals are out of phase with each other a cancellation may occur. The result would be a “drop-out.” A drop-out
sounds like either audible noise (hiss), or in severe cases, may result in a complete loss of the carrier and the sound
when the transmitter is positioned in certain locations in the room. A drop-out normally sounds like “hum” or “hiss.”
Moving the transmitter even a few inches will change the sound of the hum or hiss, or eliminate it. A drop-out situa­
tion may be either better or worse as the crowd fills and/or leaves the room, or when the transmitter or receiver is
operated in a different location.
The DR185 receiver offers a sophisticated diversity design which overcomes drop-out problems in almost any imagin­
able situation. In the event, however, that you do encounter a dropout problem, first try moving the antenna at least 3
or 4 feet from where it was. This may alleviate the drop-out problem on that antenna. If drop-outs are still a problem,
try moving the antenna to an entirely different location in the room or moving the antennas in closer to the transmitter
location. By observing the OPTI-BLEND LEDs on the front panel, you can determine which antenna is suffering
weak signals.
Lectrosonics transmitters radiate power very efficiently, and the receivers are very sensitive. This reduces drop-outs
to an insignificant level. If, however, you do encounter drop-outs frequently, call the factory or consult your dealer.
There is probably a simple solution.
REFLECTIVE SURFACE
DIRECT SIGNAL
INDIRECT SIGNAL
DIRECT SIGNAL
INDIRECT SIGNAL
TRANSMITTER
RECEIVER
PHASE
CANCELLATION
Mulit-path Dropout
6