User's Manual

Technalogix Ltd TAUD-1000 Transmitter
IV-4
Power Divider/Combiner (internal to each TAUD-500 enclosure)
A Wilkinson power divider and combiner (identical printed circuit boards) are used to split the RF
signal into, and combine the amplified RF signal out of the (3) BLF final amplifier pallets. Flanged
power resistors help ensure that any differences between the inputs or outputs are balanced.
The Wilkinson design takes advantage of the fact that an impedance transformation can take place
across a quarter-wavelength transmission line if the line has different impedance than the source or
load impedances being matched. In this case, quarter-wavelengths of 75-ohm coaxial are used to
maintain 50-ohm impedances at the input and output of the Wilkinson divider/combiner. Due to its
electrical and mechanical symmetry, the Wilkinson design’s performance over moderate
bandwidths is superior to other types. This design maintains phase and amplitude equality, in
addition to providing isolation and matched outputs.
Splitter/Combiner
The splitter and combiner are used to split the RF signal into, and combine the amplified RF signal
out of the (2) final amplifier pallets. The connectorized designs are based on the simple isolated
Wilkinson combiner design. Due to its electrical and mechanical symmetry, the Wilkinson design’s
performance over moderate bandwidths is superior to other types.
Directional Coupler
The Technalogix dual directional coupler provide DC voltages proportional to forward and reflected
RF power monitoring. These analog voltages are converted for processing using analog-to-digital
converters and provide the control system with valuable data for monitoring purposes. Output power
should be set following the operating procedure found elsewhere in this manual. The directional
coupler has a typical insertion loss of 0.5dB and its Type N connectors can handle 1,500 watts
peak. On higher power systems, 7/16 DIN connectors are used for increased power handling
capability.
Isolator
The power amplifier pallets are protected in part by the isolator located in the filter enclosure. It is
actually made up of a circulator and 50-ohm dump resistor. The circulators’ specifications include
an insertion loss of less than 0.2dB with an isolation rating better than 20dB. Any reflected power
gets dumped into the flanged power resistor. Even though the flanged power resistor is rated for
less than the transmitter’s rated power, the software will recognize quickly that reflected power is
present and turn the carrier off. This way, there is instantaneous protection due to the isolator setup
and long term protection due to the software.