A 2024 road trip took Paula and me to east Tennessee. Nestled in the rolling hills, we found Bluff City, next door to Bristol, which straddles two states and is considered by many to be the birthplace of country music.
This is also the home of Kintronic Labs, the industry’s oldest AM systems provider. It also provides products for other RF applications including FM, TV and STLs.
KTL is an ISO 9001 company. Its 30 employees are craftsmen in the trade of building RF hardware in its 54,000-square-foot facility.
Many AM stations have one or more KTL products. Probably the most common are their contactors for switching up to 200 amperes of RF, as shown in Fig. 1. To help engineers everywhere, there is an instructional video on the company website showing how to field repair and adjust a contactor.
Back in the 1970s, KTL designed wire-wound dummy load resistors with very little inductance. Dummy loads are a segment of its business, which netted a contract to build equipment for the U.S. government High-frequency Active Auroral Research Program (HAARP) in Alaska. They were installed in 2007 and none have failed despite that harsh environment.
KTL builds parts that you just can’t find on the shelf elsewhere. It takes tools to make all of this happen.
In Fig. 2 Mike Kistner uses computer-aided design to cut metal with a 55K psi waterjet. In this case, it was a copper mounting bracket for a vacuum variable capacitor, shown in Fig. 3. The part was later silver-plated to provide corrosion protection and good electrical conductivity.
AM phasing systems for directional antennas have been their main stay for many years. It all comes together when a customer request comes in. That is where Senior Staff Engineer Bobby Cox (Fig. 4) fits into the equation, designing RF circuitry to create an FCC-required signal pattern for an AM directional antenna. He has been doing that since 1994 and holds a Ph.D. in electrical engineering.
No two phasor systems are alike. Each one is designed for the job at hand. Mike Burton, shown in Fig. 5, takes a schematic diagram from Cox and creates a layout, putting mounting holes in a bare aluminum phasor cabinet. Then the cabinet parts are sent to the paint bay (Fig. 6) before they are populated with components.
Click on the picture to toggle between Fig. 5 and Fig. 6
Joshua King, BSEE, started employment at Kintronic Labs as a project engineer in 2018; he became president and CEO in 2022. His grandfather Louis King founded the company in 1949, and Joshua carries on the tradition of honesty and integrity for which the family-owned company is known. In Fig. 7 he demonstrates a phasor that was built for a station in California.
(Joshua’s father Tom King, the longtime president and now a consultant, was away on a mission trip to 4VEH radio in Haiti. He was repairing a Harris DX-10 AM broadcast transmitter to bring the gospel station up from half to full power and adjusted the directional antenna system — Christian mission work to help others.)
Senior Staff Engineer Jim Moser, BSEE and MSEE, joined Kintronic in 1995. He created custom in-house software for analysis and design of antenna systems. Moser, shown in Fig. 8, is also a project manager for domestic and international projects.
The list of creating solutions to problems continues. Networks to combine multiple AM stations into single or multiple towers have been a growing part of their business. Fig. 9 shows preliminary work on a high-power network. The company also makes make isocouplers to get FM and STL signals across the bases of hot AM towers.
Oh, and in the photo at the beginning of this article, I’m inspecting the impressive workmanship in an AM antenna coupling unit. (I recall that back in 1977, I needed equipment from KTL and called the company. I found it a bit difficult to place the order by phone because of the difference in accents between Tennessee and Minnesota. To avoid errors, the best plan was to send my orders by fax!)
It was a pleasure to visit Kintronic and see its craftsmen at work, creating equipment for the radio broadcast industry.
