VOA Bethany, OHIO
- skylarkcolo
- Dec 29, 2023
- 3 min read
Updated: Apr 15
Below I have added a lot of photos and info about the the 1944 VOA site north of Cincinnati, OH and next to Crosley's WLW broadcast location. "This place was built to take a direct hit from a bomb," said Jack Dominic, the museum's executive director. The industrial building, decommissioned in 1994, had no heat, which would have been superfluous because its interior was baked by its six quarter-million-watt VOA radio transmitters. Designed to be indestructible, the Station easily survived into the 21st century, but its interior 18-inch-thick blast-proof concrete walls made it hard to modify into a civilian-friendly attraction.
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The 1940s site layout below
The Antenna layout at the site
WW2 Station
It can be truthfully be said, that "a Rhombic antenna occupies more space per db of gain than any other antenna" The Rhombic is a very high-gain antenna however it requires a lot of acres, and the efficiency when terminated is only about 50%. An alternate impedance-termination system, which was only used for a at the VOA Bethany site broadcast site, where input powers were above 50 kw, is called the re-entrant line termination. Clyde Haehnlen SK, developed the specifications for the Voice of America antenna system at the Bethany, OH Relay Station. That re-entrant Rhombic was 90% efficient by re-phasing the power instead of heating up termination resistors, in this system, the Rhombic is terminated in a transmission line, which in turn is coupled back to the input through the proper voltage-matching and phasing networks. Thus, the energy in the dissipation line is fed back to the antenna, so that considerably less than 50 percent of the energy is wasted. The old VOA Bethany site in Ohio had efficiency up to over 90%. This feeds-backs the wasted RF energy "In-Phase", back into the feeder end of the antenna. For any variation from the stubs frequency, the stub must be returned.
Re-entrant line termination equipment, which is re-phasing the power instead of heating up termination resistors. I am now the only station (K0UO) using the Re-entrant Rhombic, which is 90% efficient by re-phasing the power back in the antenna, instead of heating up termination resistors.
Clyde Haehnle, the VOA engineer provided me with design information for re-phasing a few years ago before his passing.
Below the main antenna switch station
Above the main antenna switch station
Below 1940's home radio with SW broadcast bands, I have one just like this from my Granddads barn, which got me into ham radio in the 1960s
See Above: At K0UO, I now use a Re-entrant which is 90% efficient by re-phasing the power back in the antenna, instead of heating up termination resistors.
See the YouTube below with Clyde Haehnle, Remembering WLW 500 KW Super Power and Building VOA Bethany Relay Station. Recorded May 17, 2014 at the National VOA Museum of Broadcasting. Clyde was the last surviving engineer from the WLW 500 KW era. His stories recount some of the major achievements in broadcasting during it's heyday. The rhombic antenna design requiring extensive mathematical calculations fell to Mr. Haehnle. His work accomplished with pencil, paper and a slide rule resulted in some of the most efficient antenna arrays ever built
SEE this film below about the building of this site in the 1940s
TO SEE the complete Blog list check @ https://www.k0uo.com/k0uo
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