Midwest Radio Association, Inc. KØMSP

145.370 MHz Repeater System Overview

RF Equipment

All RF equipment used throughout the KØMSP repeater system is commercial Motorola equipment and maintained to strict commercial standards. The 145.370 MHz system utilizes Motorola Micor equipment.

Central Repeater Site

The central repeater site is composed of a Motorola Repeater and Motorola link receivers are used for linking the satellite receivers to the voting system. In addition there is a custom voter, Sinclair duplexer, RFS isolator (IM panel), RFS receiver multicouplers, and associated RF filtering equipment. The antenna system consists of a DB Products antenna with Andrew Heliax Hardline. This antenna system is shared by the repeater transmitter, the on site repeater input receiver, all link and control receivers.

Voting System

The KØMSP Repeater voting system was designed by Greg, AEØU and built by Charlie, WØCE. This voter is a clone of the popular Motorola SpectraTac Voting System. The voter continuously monitors each receiver, selecting only the strongest (minimum signal to noise ratio) signal to be aired by the repeater transmitter. Precise audio and voter channel circuitry provides seamless receiver voting.

Satellite Receiver Sites

Each satellite receiver site consists of commercial Motorola equipment. A Motorola VHF receiver, link transmitter, RFS isolator (IM panel) and RF filtering devices completes the RF section. When a signal is received by the VHF receiver (144.770 MHz), it in turn activates the link transmitter via custom logic circuitry and audio is channeled to the transmitters modulator via post discriminator custom audio circuits built by Dave KYØL. Extremely high audio integrity is achieved using our custom engineered audio circuitry. The satellite receiver link transmitter is then received by the associated Motorola link receiver at the central site and forwarded to the voter for processing.

Radio Association, Inc.
Minneapolis/St. Paul



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