MARA SYSTEM DESCRIPTION

146.850 Mhz Repeater Transmitter

The MAIN 146.850 Mhz repeater transmitter is located on one of the City of Oakdale’s 180 foot high water tanks located just north of the intersection of Interstate Highways 94, 694 and 494 on the eastern edge of the Twin Cities Metro Area. Our repeater transmit antennas are mounted on the top of this water tank.

The 146.850 Mhz transmitter used as the MAIN transmitter at Oakdale, is a solid state 500 watt continuous duty transmitter set at 450 watts of RF output power. It feeds a CELWAVE Super Stationmaster fiberglass stick) antenna mounted on top of this 180 foot high tank via 200 feet of 7/8” Heliax cable. Our calculated output power from this transmitter is about 1000 watts ERP (Effective Radiated Power). This transmitter site and equipment provides a solid signal in a 60 mile radius circle of coverage (suitable for mobile and handheld radio operation) from its location about 300 feet above the average terrain in the Twin Cities area.

A standby 100 watt output MOTOROLA MICOR continuous duty transmitter is also located at the Oakdale site connected to a external dipole type antenna also mounted on top of the water tank. Another backup 100 watt MOTOROLA MICOR continuous duty transmitter, with an external dipole type antenna mounted on top of the White Bear Lake south water tank can also be used.

146.250 Remote Receiver sites What makes the 25/85 repeater system operate so good are the multiple receiver sites used to pick up your transmitted signal on 146.250Mhz. Each of these six remote receive sites are linked to the White Bear Lake "Repeater Central". Any of these receive sites would make an excellent stand-alone repeater site,and in fact a lot of them share sites where other Amateur Radio or Business Band repeaters are located. The remote receive sites for the 25/85 system are located at:

449.800/444.800Mhz Repeater System MARA also operates a stand-alone 440 Mhz repeater on 449.800/444.800 Mhz . This Motorola MSR5000 100 watt output repeater feeds a 6 dB gain Super Stationmaster antenna which is located at the 180 foot level of a 240 foot tower on Prior Ave in the Midway area between Mpls and St. Paul. You will find this repeater has a coverage of about a 30 mile circle around the repeater site. The CTCSS access tone needed for this repeater is 114.8 Hz.

LOCATION

SITE ID

DESCRIPTION

Ramsey

NORTH WEST

On a Water Tower

Minnetonka

WEST

On a water tower in Minnetonka (near Hwy 7 & I494)

U of M Campus

CENTRAL

U of M Twin Cities Minneapolis Campus building rooftop

Scandia

NORTH EAST

Shares 120 ft high tower used for 146.73 repeater

White Bear Lake

ON SITE

On South Water tower of White Bear Lake (Near Century College)

West St. Paul

SOUTH

Hilltop site just off S Robert St., south of downtown St. Paul

Roberts, WI

EAST

Just north of Roberts

White Bear Lake “Repeater Central” operation

The White Bear Lake water tank site is not only a 146.250 Mhz receive site but also acts as “Repeater Central” for the 25/85 repeater system. This site not only receives repeater input signals from its local 146.250 Mhz receiver but also from the 440 Mhz auxiliary link signals from all of the 6 remote receiver sites. These signals are fed into a unique voting system (receiver select system) that constantly samples the incoming receiver signals, where the best one is selected for retransmission on 146.850 Mhz. Other repeater features are added at WBL “Repeater Central”, such a system IDs and courtesy beeps, and then the selected receiver signal is transmitted via another 440 mhz auxiliary link transmitter to the MAIN transmitter at Oakdale. All functions and operation at this WBL site are monitored and different transmitters or receivers can be controlled ON and OFF by a remote control system. All of the critical equipment at the White Bear Lake site is backed up by a UPS system that will allow it to keep operating for 1 to 2 hours after an AC power fail.