Featured Product Archive
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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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:
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 BCC.
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
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
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
See the LBA Technology press release.
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.
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.
LBA Group, Inc.