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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Hi Kirt,
 
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.
 
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.

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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.
 
 
Patrick Stox
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See the LBA Technology press release.



About LBA Technology, Inc.
LBA Technology 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.

Patrick Stox
LBA Group, Inc.
pstox@lbagroup.com
www.lbagroup.com
252-757-0279
800-522-4464