You would have to have been around Jon Crick during the whole of his broadcast engineering career to appreciate the enormous breadth of his talents and experience. He fixed fixed radio and TV transmitters, enormous videotape machine pneumatic systems, digital videotape recorders, big audio mixing consoles, the Sony Library Management System robotics and studio camera robotics. He operated satellite news trucks big and small, wired 100-amp UPS devices, planned multi-camera shoots, and installed production switchers. The documentation was always before he started a project. Then there are the multiple musical instruments Jon can play with complete competency.
A year ago I was helping out temporarily at Bext with technical service and a number of interesting challenges came up. One was from a customer whose low power FM transmitter shared a site with a mobile carrier. The carrier’s technician was complaining about the transmitter’s 8th harmonic getting into his radios. The FM transmitter in question was clean far beyond FCC requirements of -80dB below assigned carrier level (as I remember, about -96dB) but on a spectrum analyzer, you could see a tiny bump down near the noise floor in the 800 MHz band. I used the analyzer and its tracking generator to trim a hunk of coax and knock down the 8th harmonic of the offending FM transmitter about 20 dB. That’s a pretty short piece of coax, by the way. Problem solved and nobody had to build a Faraday cage.
A June article in the BDR mentions this conflict between the very sensitive LTE mobile site receive inputs and their FM transmitter neighbors. These radios are attempting to discriminate data at -120 dBm and lower from distant tiny transmitters inside metal cars and buildings.
I first ran into an application for a stub with a TV translator site in the Oregon high desert in the early 80’s, where I was receiving a faint UHF signal beyond line-of-sight and picking up some birdy from my channel 5 output. With an N-connector “T” adapter and a quarter-wave length of RG-213, I fashioned an open-ended stub that resonated at the mixer product, attenuating it enough to remove the problem from the visual band of my UHF input.
Another recent article in Radio World magazine, this by Mark Persons, suggests putting a bandpass filter in the form of a quarter-wave shorted (not open) stub after a solid-state amplifier feeding a tube amplifier. This is brilliant. It serves to attenuate voltage spikes that might enter since only the resonant frequency passes without great loss–DC and pulses slow and fast are shorted out. By the way, this won’t work with TV or other broadband applications due to the high-Q of the stub.
Check out articles on construction of these stubs online.
UPDATE 7/22/2013 – Analog stations along the border are now off the air, apparently permanently after elections.
UPDATE 5/13/2013- Analog stations along the border are back on the air today after electoral candidates complained about lack of exposure ahead of July 7 elections.
Eight Tijuana TV stations went dark May 28, 2013 as the first broadcast market in Mexico to go all-digital, delayed a month from the previous target date of April 16. Those stations included:
XHTJB channel 3, affiliated with Once TV, public/educational
XETV channel 6, Televisa O&O, affiliated with Canal 5
XEWT channel 12, Televisa O&O, affiliated with multiple networks
XHTIT channel 21, TV Azteca O&O, affiliated with Azteca 7
XHJK channel 27, TV Azteca O&O, affiliated with Azteca 13
XHAS channel 33, Entravision operated, affiliated with Telemundo
XHBJ channel 45, Cadena owned and Televisa operated, affiliated with Galavision
XHUAA channel 57, Televisa O&O, affiliated with Canal de Estrellas
Notably, XETV had just celebrated 60 years of broadcasting, having signed on with English language broadcasting in 1953 and continuing to do so until last year, when it switched to Televisa’s Spanish-language broadcasts of Canal Cinco. XETV-DT was the first digital TV station to broadcast in Mexico in 2000, and likely the inspiration for having Tijuana selected as the first market to shutdown its analog TV.
Mexico’s EFE indicates that over 192,000 free digital TV converters were passed out to Tijuana area residents as part of the transition. Unconfirmed statistics have 48% of Tijuana residents receiving their TV via free over-the-air broadcasts.
Interestingly, Entravision-operated XHDTV on Cerro Bola near Tecate remains on the air on channel 49. The next shutdown date, November 26, 2013 is supposed to include Mexicali, but it is not known whether XHDTV will shutdown at that time.
What is not yet known is how the empty channels will affect FCC-mandated repacking of TV channels along the border. There’s likely to be a scramble on both sides of the border to occupy the empty lower UHF channels.
Francisco Laurent Martinez, who served as engineer and Chief Engineer of the Transmission Department at XETV in Tijuana from 1959 till this month, passed away March 24, 2013 in Tijuana. He saw the facility progress from a single English-language ABC affiliate for San Diego to a cluster of eight Televisa-operated TV stations, all now with solid-state transmitters and antennas on two self-supporting 500 foot towers.
He mentored engineer Humberto Borzani, who told us Francisco was born December 7th, 1930 in Tijuana. He graduated in 1956 as an Engineer with a major in Electronics and Communications in Mexico City. He served as Chief Engineer of the Radio Monitoring Station of SCT (the Mexican equivalent of the FCC) from 1972 to 1987. The SCT sent him to Washington to coordinate cross-border frequency allocation studies in 1979.
Francisco served as professor at the Instituto Tecnológico de Tijuana from 1971 till 1987, and was founder of the associated cultural FM station Radio Tecnológico 88.7 MHz FM from 1987 till 2005.
On a personal note, I worked at XETV’s U.S. operations from 2004 till 2010, but was always warmly welcomed at the Mexican master control and transmission site. I have never seen a transmitter site like the one Francisco led, from the marble floor at the entrance and master control rooms to the spotless transmitter rooms to the twice-filtered air and shiny copper transmission lines. The 1955 GE transmitter was ready for air until just a few years ago. Their UPS and generator backups kept the transmitters going without interruption for years at a time. Francisco was justifiably proud of that facility, and he will be missed.
At 3:40 pm on September 8, Paul Redfield, Director of Technology at XETV, heard a faint click from his San Diego TV production control room. He saw the hall lights go out briefly, but the production room lights and equipment hummed along. A few seconds later the hallway lights returned as their 600kW generator kicked on, replacing the missing street power.
Outside, traffic lights went dark, creating lines of cars with drivers waiting to cross intersections tentatively, one or two at a time. Car radios heard either static, or silent carriers, or the rare voice trying to make sense of the electrical outage that seemed to be affecting listeners calling in from throughout San Diego and Imperial Counties, as well as southern Orange County and Yuma, Arizona, affecting 1.4-million customers total for up to twelve hours. Continue reading What Happened to San Diego Broadcasters When the Lights Went Out→