Shure UA874, Manual

Page: 3 / 44

3
Selecting Antenna Cables
Use 50 ohm low-loss coaxial cable, such as RG-8U. Shure offers pre-
terminated antenna cables ranging from 6 to 100 feet.
NOTE: When ordering cables from Shure, select the low-loss "Z" models
(available for longer cables) when using frequency bands above 1000
MHz.
Active Directional Antenna
General Description
The Shure UA874 uses a log periodic dipole array to offer enhanced
reception when directed toward the desired coverage area. An integrated
amplifier and four gain settings compensate for varying degrees of coaxial
cable signal loss. The UA874 can be mounted on a microphone stand,
suspended from the ceiling, or mounted to a wall using the integrated
swivel adapter.
Features
• Low-noise signal amplifier compensates for insertion loss in coaxial
cable
• Compatible with Shure wireless receivers and antenna distribution
systems that provide 10–15 V DC bias
• Integrated threaded adapter mounts easily to microphone stands
• Four-position gain selector switch
• Shure quality, ruggedness, and reliability
Note: The antenna will not operate without 10-15 V DC bias. This is
required even at -6 dB and 0 dB ("passive") gain settings.
Installation
• Connect the antenna to the receiver or distribution system using
Shure antenna cables (or any 50 ohm, low-loss coaxial cable, such as
RG-8U).
• The antenna only operates with receivers or distribution systems that
provide 10–15 V DC bias.
• Lower the gain setting for short cable runs, or increase gain for longer
runs. Note that the quality of the cable, not just the length, contributes
to signal loss. A lighter-grade 50 foot cable may require more gain than
a 100 foot, low-loss cable. Contact the cable manufacturer for cable
loss specifications.
• Direct the antenna toward the intended coverage area.
• Do not use this antenna for transmitting (such as with PSM
transmitters)
Cable Maintenance
To maintain top performance for antenna cables:
• Avoid sharp bends or kinks in the cables.
• Do not deform cables with makeshift clamps, such as bending a nail
over the cable.
• Do not use in permanent outdoor installations.
• Do not expose to extreme moisture.
Interface
① Gain Switch
Adjust the four-position gain switch to compensate for the calculated
cable loss, based on the length and type of cable.
Caution: There may be a small RF dropout when changing the gain setting.
② Gain Mode LED
Indicates the current gain switch setting.
③ RF Overload LED
Indicates a strong RF signal that is overloading the antenna amplifier,
which results in distortion or poor performance. Increase the distance
between the antenna and transmitter, or lower the antenna gain
setting.
NOTE: RF Overload LED does not operate for passive gain settings (−6 dB or 0
dB).
④ BNC Connector
Connect to a receiver or antenna combiner with RF inputs that supply
10–15 V DC bias.