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WLDR-FM, Traverse City, Michigan: Shared Aperture FM Antenna

This 1,000-foot tower support WLDR-FM’s ERI Model SHPX-8BCSP/LP-6C-SP Shared Aperture FM antenna. The antenna is an interleaved array made up of a high power 8-bay SHPX Series ROTOTILLER® for the analog FM signal and a low power Model LPX-7C ROTOTILLER® for the digital HD Radio™ signal. To provide additional isolation the antennas are cross polarized, the analog signal has right hand circular polarization and the digital is left hand circularly polarized. Photo courtesy of Doc Searls and can be found at flickr.

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WTCM-FM 103.5 MHz Traverse City Michigan

The tower pictured is a 996-foot guyed tower that supports WTCM-FM’s main antenna which is an ERI manufactured G5CPS-10AC, which is a private labelled FM antennas built for Continental Electronics. If you look carefully you can see WTCM-FM’s auxiliary antenna which is an ERI Model 300-3AE vertically polarized FM antenna at 615-feet above ground level. Photo courtesy of Doc Searls and can be found here: flickr.

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AXIOM® Master FM Antenna on Mount Wilson

This is an auxiliary AXIOM® Master FM Antenna for KBIG/104.3 (21kw), KIIS/102.7 (4kw), KOST/103.5 (10kw) and KRRL/92.3 (19kw). The antenna is a true broadband master FM antenna, this model is an 8-bay version. The array has half wave bay-to-bay spacing and has a unique feed system that is broadband over 18 MHz of the FM band. Photo courtesy of Doc Searls and can be found at flickr

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New TRASAR® UHF Television Antenna in Final Test

This is a top mounted, elliptically polarized,  UHF TRASAR® television antenna in the process of having final test data taken. All ERI top mounted television antennas are provided with dedicated climbing facilities that do not penetrate the radome. This prevents potential contamination or moisture intrusion into the antenna radome which can cause corrosion, impact electrical performance and shorten the antenna’s useful life. This also provides climbers superior access to the beacon and improves safety.

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Another 788 All Pass™High Efficiency FM Analog/HD Radio™ Diplexer in Assembly

This item is an ERI Model 788A-SP High-Efficiency FM Analog/HD Digital Diplexer. ERI’s innovative All Pass™ design allows stations to operate hybrid digital with HD Radio™ power levels up to -10dBc. The All Pass Diplexer maintains high efficiency while incurring a much smaller penalty to performance than other methods currently available. The analog insertion is less than 0.35 dB, and the digital HD Radio signal loss is less than 1.4 dB with digital group delay variation less than 600 nsec and is fully compliant with the HD Radio™ FM Transmission System Specifications. The 788 is an ideal choice for FM stations that have very high FM transmitter power output requirements due to long transmission line runs and also have the desire to operate at elevated HD power levels.

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ERI CF103 Low Power FM Group Delay Equalizer

The ERI Model CF103 Low Power FM Group Delay Equalizer provides group delay pre-correction for FM transmitters at low level, usually between the FM transmitter’s exciter and intermediate power amplifier.  The pre-correction applied offsets excess group delay variation and asymmetry that is unavoidable in FM combiner systems that include closely spaced frequencies, of 1.8 MHz or less.  The CF103 has a power rating of 150 watts and provides up to one microsecond of correction across a single FM broadcast channel.  ERI also has available group delay equalizers that operate at high power, which offer greater correction range and are located directly before each individual station’s combining module.

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WDAE, AM 620, Tampa/St. Petersburg the First Directional AM Array

The tower pictured is one of two (2) 360-foot base insulated AM towers that straddle West Gandy Boulevard, the Courtney-Campbell Causeway. This AM facility operates at 620 kHz and was originally owned by the City of St. Petersburg and operated with the Call Letters WSUN and in 1932 became the first directional AM facility. The directional nighttime pattern protects co-channel WTMJ, Milwaukee. These two towers were designed, fabricated and installed by ERI 2005. The base section of each tower is a four-sided structure that matches the base dimension of the original towers built in 1932. Each tower transition to a traditional triangular configuration for most of their height.