Copyright ©1998, RF Specialties Group.
New and improved
signals are in the air for the McKenzie River Broadcasting Company's two FM stations
in Eugene, Oregon, KMGE and KKNU. The stations purchased a Shively 6814 series
antenna and branched combiner from RF Specialties of Washington in 1997. The two
signals radiate from atop the company's tower on Blanton Heights, just south of
the city.
The single antenna, located on a pole mounted on top of the tower, replaced
two separate antennas purchased from Shively several years ago. KMGE previously
transmitted from the same pole, while 
KKNU was side-mounted 300 ft. lower on the tower. Chief Engineer Chris Murray
reports that KKNU is now receiving signal reports from cities it never reached
before, and that KMGE notes no difference from its previous coverage, despite
a 50% reduction in output power. Both stations have seen a significant reduction
in multipath in the southern edge of the city due to the addition of 18% first
null fill.
The Shively 6814 antenna was tuned for optimum performance on both station's frequencies (KMGE is on 94.5 MHz, while KKNU is on 93.1). The bandpass combiner consists of two forced-air-cooled, three-section bandpass cavity filters.
McKenzie River Broadcasting is a longtime customer of both RF Specialties and Shively Laboratories.
Photos:
1. In October, 1997, Shively Laboratories sent Bob Surette, Dale Ladner and Shawn Edwards (L to R) to Eugene to optimize the tuning of the combiner.
2. An end view of the Shively combiner, showing the input lines for each station and the air hoses for the cooling fans, located on the floor below this view. The T-junction outputs and a coaxial switch are visible at the far end.