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I have been in FM broadcasting full time since 1982. I currently own five stations. My father started an FM the year I was born in 1960. We owned several stations together back then. Working for Stu (my dad) was great training for me, and I've been around the radio business all of my life.
My experience includes building several RF facilities. In doing so, I have used many brands of antennas with power ranges from 800W to 100kW.
In the fall of 1991 our family expanded our Manistique, MI, business and built our first 700' structure and installed a medium-power Jampro antenna. For the installation we used an antenna with 1⅝" antenna bay interconnects. This was a mistake because the bay interconnects can't survive in the windy conditions at that height. Jampro acknowledged that it was too light duty for that harsh environment. We learned this after experiencing a couple of burn outs.
|Performance at a glance|
Accepts 50kW input power
Marine brass and copper construction
Multiple-frequency designs available
VSWR of 1.10:1 +/-200kHz
Available with radomes
To remedy the situation, Jampro supplied new 3⅛ interconnects, which cured the trouble. I've always appreciated this level of customer service from Jampro.
When we sold the station in 1999, it was forced to change frequencies. The new owners installed a new 10-bay antenna from another manufacturer for the new frequency. After the upgrade, an evaluation of the signal strength at 60 miles showed that the new antenna from another manufacturer did not perform nearly as well as the Jampro Penetrator that was used in 1991. The station was now non-existent in the market we previously served with the old 10-bay Jampro. Jampro proved its value to me once again.
The JHPC series of antennas are available to cover the entire FM band, and systems can be installed with a variety of options. Antennas can be made directional to fit a specific coverage area, and Jampro can perform pattern measurement studies to tailor an antenna's coverage. Likewise, reduced-RF arrays can be fabricated, and electrical beam tilt and null fill can be designed into a system. Custom mounting brackets can also be ordered for unique installations.
In November 2001 I began working on another 700' tower project, this time in Marquette, MI. I called my old tower sales representative, who had joined a new tower and antenna manufacturing company. He visited the site and recommended a tower, transmission line and an antenna package that included the company that he had gone to work for. While I was already pleased with Jampro from past experience — and this package did not include Jampro — I accepted the proposed package, which allowed me to work with only one vendor. I installed a four-bay and a 10-bay antenna from this company.
The last few days of 2005 brought rare and severe icing to Marquette, which lies outside the ice belt of the Midwest. To my dismay, my four-year-old four-bay failed. The antenna apparently took a winter lightning strike, accumulated ice, shorted and failed. I had to decide between replacing the four-bay with an antenna from that same manufacturer, or give Jampro another try. I decided to go with Jampro. I ordered a high-power Penetrator and added radomes to eliminate the potential icing problem.
This past April, the decision paid off again. After three months of tough weather, Marquette experienced more heavy ice. The new four-bay Jampro with radomes stayed on air when the 10-bay (mounted below the four-bay) yielded a high VSWR that tripped the transmitter. I could not use the 10-bay for three days until the ice fog left the area and the wind picked up to carry the ice away.
This experience showed me that all antennas are not created equal. Going forward, my choice of high-power antennas for high towers is simple: Jampro Penetrator with radomes. It stays on in the ice and delivers a farther reach. I need that.
Noordyk is president of Great Lakes Radio, Marquette, MI.
Editor's note: Field Reports are an exclusive Radio magazine feature for radio broadcasters. Each report is prepared by well-qualified staff at a radio station, production facility or consulting company. These reports are performed by the industry, for the industry. Manufacturer support is limited to providing loan equipment and to aiding the author if requested. It is the responsibility of Radio magazine to publish the results of any device tested, positive or negative. No report should be considered an endorsement or disapproval by Radio magazine.
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