This page is a virtual site visit to transmitter plant of XETRAFM, Tijuana, Mexico, which is licensed at 100 kilowatts. Examining the XETRA transmitter, antenna and tower system provides the actual effective radiated power of XETRA, and a confirmed accuracy of the ERP calculations. The Antenna system and tower are manufactured by ERI. The system uses 110 ft. of 3 1/8" hardline. They also have a one-bay antenna fed with 3 1/8" heliax.The combination of a ten bay, full wave spaced optimized antenna, mounted on a custom ERI tower, is providing an unknown power gain in the direction of the United States. As with most of the Tijuana stations, the target audience is not Mexico, but the United States, and San Diego in particular. So despite the fact that XETRA-FM is licensed to operate with 100 kilowatts, XETRAF could easily be placing well over 100,000 watts in the direction of the United States, based upon use of this transmitter/antenna/tower combination. According to un-named sources, the tower is not a lamda-type tower. But the appearance of this tower has the trademarks of such an installation. Until further evidence is found, it is likely that XETRA-FM is operating as they claim, with 100,000 watts.
Above, the XETRA-FM tower and Antenna. The system includes a ten element antenna, installed on an ERI tower. There is a one-bay standby antenna mounted below the main antenna array. Below, the XETRA transmitter system, looking east across the front.
The XETRA-FM transmitter system. The system includes two Continental 831G-1B transmitters, operating one at a time into the main-auxilliary antenna switch. The transmitters are driven by two separate BE exciters, Optimod 8200 digital audio processors, and Modulation Science composite clippers. The programming is supplied via satellite link from studios in San Diego.
Detail view of transmitter two, showing the Bird Wattmeter at 20KW TPO.
The modulation monitor, showing the meters nearly stationary at 103% during normal music programming. Very heavy audio processing and clipping provide very little dynamic range to the on-air audio.
The RF patch panel and coax switch. The XETRA transmitter is an occupied site, with an engineer available at all times to deal with any switching as needed.
This local, on-site studio is used when the satellite link fails, or when local programming mandated by Mexico is being broadcast.
© 2002 Broadcast Engineering Services of Bonny Doon