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Sierra H: The Transmitter Goes Over the Mountain
Fire on the mountain
With space in the transmitter site being at a premium the project was done in stages. Removing the Platinum-Z and NV30 transmitters and installing the new main Flexiva for KAJM while keeping the station on the air was first. Repositioning equipment racks and installing coaxial transfer switches was next. Retuning the antenna, installing the six-cavity ERI T combiner and the new main Flexiva for KNRJ followed. The last thing to do was bring both the station's new backup transmitters up the mountain for installation.
As luck would have it, a forest fire broke out just as we planned to head up the mountain, cutting off access to the site. Within a day the fire had burnt down 16 utility poles, cutting off electricity to the site. The generator kicked in, and with 3,000 gallons of fuel and a burn rate of roughly 1,000 gallons a week we counted the days.
Ultimately, we lost power when heavy air tankers dropped water and slurry on the mountaintop to cover firefighters on foot who had been cut off trying to maintain containment lines. Our Cummins generator was waterlogged and power was lost, but firefighters saved the site.
It was at this point that we put the FlexStar exciter to the test. I located a hill in town for an emergency facility that kept us legally within out 60dB contour. After filing the FCC paperwork, we installed vertical dipoles shipped overnight from Shively, pulled the exciters from the backup transmitters, dialed in the needed changes and fired them up. The exciters proved stable and allowed us to broadcast at 35W, keeping both stations on the air until we could regain access to the site several days later to fix our generator and re-fire the mains.
Sight and sound
The exciter not only helps to produce good sound but also offers a built-in spectrum analyzer to better understand coverage and audio artifacts. Multiple metering points along the transmission line, as well as output from the combiner, offer additional insight into the overall audio picture. It's helpful to evaluate the various samples and paths to gauge if any auxiliary equipment is tainting or coloring the audio.
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