The N3KZS Repeater System
The N3KZS repeater is located in Manchester, Maryland. Its primary VHF frequency is 146.895Mhz and is also linked full time to two other amateur bands. A secondary transmitter at the main site is on 224.120 Mhz and transmits exactly the same information as the 2 meter transmitter. Additionally, the system has two 6 meter repeaters that are selectively linked to the repeater system. They are normally left connected full time but can be split off if needed. Additionally, a selectable link to the N3KZS repeater in Ocean City, Maryland is in place via the internet.
The Repeater System is comprised of 9 VHF receivers that are located throughout the Maryland and Pennsylvania area. They are linked back to the main site via UHF and then are routed to a Doug Hall Voter (http://www.dheco.com/index.htm). This voter compares the signal-to-noise ratio of each UHF receiver’s signal and then picks the quietest signal. It is being run in a dynamic mode so the voting is happening very fast and basically creates a situation where the repeater has diversity reception. Very few signals will picket fence unless they are at the very edge of the coverage area.
The voter data is output to a program, that was written inhouse, that logs all receiver activity and votes to a MYSQL database. There are 3 VHF transmitters on the system that are used to enhance the coverage area. To select which transmitter works best for the station using the repeater, the voter information is processed via the steering program. When the operator unkeys his transmitter, it selects the responding repeater transmitter based upon his location that was derived via the voting. This allows communication over a much extended area and is totally transparent to the user. The capability to manually select the transmitters is incorporated to allow selecting one transmitter in the event there are multiple stations in a round table.