A BIAST is used with the UFM50 antenna amplifier. It provides DC phantom power on the coaxial line to the UFM50 so a customer does not have to run a separate cable to power the UFM50. Some Lectrosonics receivers already have phantom power built in to the antenna connectors and don't need a bias T.
Using the bias T at the receiver with a CH-20 will put 12 VDC at up to 150 mA to power the UFM50. The internal polyfuse is a 300mA unit and should allow 150 mA under any temperature conditions. The UFM50 pulls 85 mA at 12 VDC. Good quality UHF cable, should allow several miles of length before resistance drops would reduce the available voltage. Since the amplifier can only compensate for 400 feet of Belden 9913, the lowest loss medium sized cable, this will never be a problem.
The bias T consists of a feed inductor to apply DC to the BNC that goes to UFM50 (the antenna side) and a blocking capacitor to keep DC off the receiver BNC side. The RF is connected directly from one BNC to the other with only the blocking cap in series. A locking power jack connects to the CH-20, the recommended power supply. A series diode and the polyfuse are in the circuit for protection against reverse voltage and shorts.
The Bias T is effective from 60MHz to 950 MHz with less than 1 dB of loss. From 150 MHz to 850 MHz the loss is less than .5 dB. The unit is labled for customer ease of operation.