A couple weeks ago, RF Cafe visitor Patrick Stox, of LBA Technology, contacted me with a story and photos of an
über triplexer project that engineers at the company had completed. The pictures alone of these huge filters are
cool enough, but the location for installation is really unique. Here is Patrick's story:
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From left to right, Senior RF Engineer Marvin Brewer, President and CEO of LBA Group, Inc. Lawrence Behr, Chief
Technical Officer Chris Horne, Technical Director Marcian Bouchard
LBA-made Triplexer for BCC in Taiwan fully exposed
Triplexer unpacked and on site in Taiwan
LBA-made Triplexer for BCC in Taiwan with only one door open
This is a project some of your engineering readers at RF Café would find interesting. LBA
Technology has shipped a specially built advanced technology Medium Wave Triplexer system to the Broadcasting
Corporation of China for installation in Taiwan. This is the second major multiplexer system LBA has furnished to
The BCC site created a number of challenges. Site limitations required that the triplexer operate into an
electrically short tower in the middle of a lake, with only a small platform area 30 feet above the water
available for the tower base and the triplexing equipment.
LBA senior engineer Marvin Brewer simulated the electrical requirements by NEC
modeling and specified the installation of an LBA Technology Q-Cage™ broadbanding kit on the tower to improve
matching impedances. He then designed a triplexer system in three independent ATU – RF filter combinations. These
weatherproof cabinets were designed to cluster around the tower base, while permitting adequate maintenance
access. The LBA Technology shop experts fabricated, adjusted, and tested the entire system.
The Q-Cage for
this project was designed to be installed on a guyed, base insulated (series fed), uniform cross-section, medium
wave radiator that is 108m in height with a face width of 686mm. Across the MW broadcast band (540 kHz – 1700
kHz), the unit can be used for transmitter output powers up to 100 kW. It should be noted that the Q-Cage
installation will not alter the normal configuration of the base insulator, grounding system or RF feed system
employed for the tower.
As its name implies, a triplexer allows the multiplexing of three medium wave AM
transmitters into a single antenna. Triplexers include an antenna tuning unit and rejection filter sections for
each frequency to allow the passing of the desired frequencies while rejecting the undesired frequencies. The
triplexer system for BCC was designed for 531 kHz, 648 kHz and 963 kHz, and 10,000 watts power at 125% modulation
for each frequency.
The triplexer system was delivered through international transmitter manufacturer
Broadcast Electronics in Quincy , IL. LBA has partnered with BE on projects in the United States, the Middle East,
Far East Asia, Afghanistan, Iraq, and the United Kingdom.
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See the LBA Technology press
About LBA Technology, Inc.
is a leading
manufacturer and integrator of radio frequency systems, components and test equipment for broadcast, industrial
and government users worldwide. With
Lawrence Behr Associates
, Inc., the company is a unit of
LBA Group, Inc
, which has nearly 50 years experience in providing support for infrastructure assets of the
wireless telecommunications industry. The companies are based in Greenville, NC.
The inventions and products featured on these pages were chosen either for their uniqueness in the RF engineering realm, or are simply awesome
(or ridiculous) enough to warrant an appearance.
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