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.
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.
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.|
Use 50 ohm low-loss coaxial cable, such as RG-8U. Shure offers pre-terminated antenna cables ranging from 6 to 100 feet.
To maintain top performance for antenna cables:
Use the following guidelines when mounting antennas:
Important: Always perform a "walk around" test to verify coverage before using a wireless system during a speech or performance. Experiment with antenna placement to find the optimum location. If necessary, mark "trouble spots" and ask presenters or performers to avoid those areas.
The gain setting should only be used to compensate for the calculated cable signal loss. Additional signal gain does not mean better RF performance. Too much gain actually reduces reception range and the number of available channels. This is because Shure receivers are optimized to deliver the best performance when the sum of signal gain and cable loss equals 0 dB. Additional gain just amplifies everything in the RF range—including interference and ambient RF noise. It cannot selectively increase the signal from the transmitter.
Use the following chart as a guideline for setting gain based on cable type where the distance from the antenna to the transmitter is greater than 100 feet.
NOTE: For installations where the antenna is less than 75 feet from the transmitter, lower the gain setting one step.
|Cable Length||Gain Setting (based on cable type)|
|10' (3 m)||0||0||0||0|
|25' (8 m)||+6*||0||0||0|
|50' (15 m)||*||+6||+6||0|
|100' (30 m)||*||+12||+6||+6|
* RG58 cable has high signal loss and is not recommended for cable runs greater than 10 feet
** Low-loss RG8/RG213 cables include Times Microwave Systems LMR400 and Belden 9913 or 7810A
For more information, visit http://www.shure.com
10 to 15 V DC bias from coaxial connection, 75 mA
3 dB Beam Width
±1 dB, Switchable
+12 dB +6 dB 0 dB −6 dB
RF overload LED does not operate for passive gain settings
559 x 435 x 68 mm (H x W x D)
765 g (27.0 oz.)
−18°C (0°F) to 63°C (145°F)
−29°C (-20°F) to 74°C (165°F)
This product meets the Essential Requirements of all relevant European directives and is eligible for CE marking.
The CE Declaration of Conformity can be obtained from: www.shure.com/europe/compliance
Authorized European representative:
Shure Europe GmbH
Headquarters Europe, Middle East & Africa
Department: EMEA Approval
75031 Eppingen, Germany
Phone: 49-7262-92 49 0
Fax: 49-7262-92 49 11 4