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User Report: GatesAir Springs Into Action for KTHK

Quick turnaround and clearer signal support Idaho broadcaster

GatesAir Flexiva FAX20 air-cooled transmitterThe author is IT and engineering manager at Riverbend Communications.

IDAHO FALLS, Idaho — KTHK is a commercial, 100 kW station owned by Riverbend Communications broadcasting KTHK(FM)/105 The Hawk throughout the southeast Idaho region including Blackfoot, Idaho Falls, Pocatello, and Rexburg.

The main 105.5 MHz FM signal, which has an ERP of 100 kW, propagates from a butte near Idaho Falls, and is supplemented with a translator on 105.9 MHz FM to service the tricky Pocatello geography.

It’s an overall challenging market to cover that was further complicated as our main tube transmitter, with a manufacturing badge dated 1978, had been increasingly hindered by component failures.

Parts became more expensive and harder to source with each passing year. The transmitter finally suffered an untimely critical failure, and an immediate replacement was ordered while the station ran on an auxiliary backup.

Fortunately, plans were in motion to replace this transmitter, and comparisons and evaluation had already been made that led to the decision of a GatesAir Flexiva FAX20 air-cooled transmitter.

The theory of operation seemed very sensible. Individual, hot-swappable power supplies for each power amplifier module will make future replacements quick and easy.

Redundancy is improved since the IPA and power amplifier modules for each power block are the same and interchangeable. General maintenance is swift and simple with occasional filter cleaning, with internal building temperature monitored by remote control.

Time was of the essence since the project changed from a planned transition to an immediate replacement.

We had two major concerns: factory lead times due to COVID-19’s impact on supply chains, and the weather condition’s effect on site accessibility. Nick VanHaaster, our GatesAir sales representative, as well as their manufacturing and shipping divisions, were helpful in sourcing a new transmitter quickly.

It is almost unavoidable with Murphy’s Law applying to emergency engineering, and we still ran into a major two-week delay with the freight carrier. Thankfully, the quality of the packaging materials and assembly alleviated most concerns. The two inches of snow expected at the tower site on the projected arrival date had turned into two feet of snow when the transmitter reached us.

After initial inspection, it was determined that the transmitter could be safely transported in the original crating covered in tarps for temporary waterproofing. With the transmitter arriving in two crates, the weight could be distributed on a flatbed trailer and towed by a 4×4 truck with tire chains.

Compared to the amount of work that went into removing the old tube transmitter, installation was very quick. After running new rigid transmission line to the combiner and three-phase delta power via top access, the transmitter was on and running into a dummy load within hours.

We have seen noticeable improvements in performance and efficiency. The difference in broadcast clarity was immediate, while reduced power consumption has had an immediate impact in utility cost savings.

Smooth operator

The operation has been perfectly stable, with no issues since the transmitter came to air. In addition, the ground footprint is significantly less than the old tube transmitter, leaving room for another rack and future infrastructure.

This transmitter utilizes the GatesAir Flexiva FAX50 exciter, which is as easy to configure. The exciter is fed audio via composite from an Omnia processor, and the transmitter is output via Myat 3 1/8-inch rigid transmission line to an ERI combiner installed two years ago. From there, it is combined with another solid-state transmitter and run to a directionally polarized Jampro antenna bay.

Overall, this transmitter has exceeded high expectations. When it comes to installation, functionality, operation, broadcast clarity and efficiency, the affordability borders on unique. Even after the warranty expires, our expectations are that parts, labor and most importantly main transmitter downtime will be drastically diminished.

We look forward to adding more of the Flexiva line of solid-state transmitters to our fleet, and the additional savings in operating costs we will see in the future.

Radio World User Reports are testimonial articles intended to help readers understand why a colleague chose a particular product to solve a technical situation.

For information, contact Keith Adams at GatesAir in Ohio at 1-513-459-3447 or visit