DCARA has 3 sites that all share a common control radio frequency. This allows us to link some repeaters in half-duplex, as the control link radios are a single Motorola CDM1550.

All control radios operate on the same frequency, so linking a repeater to a control radio can be thought of as adding it to a group or pool.

To link and unlink certain repeaters, it is important to understand how these sites are internally configured.

• Port 1: 146.92 (TX/RX)
• Port 2: WX-250 (RX)
• Port 3: Control Radio (TX/RX, half-duplex)

The 146.92 site is the most simple of the bunch. Linking or unlinking the 92 and Control Radio simply routes audio from the 92 receiver to the Control Radio transmitter, and from the Control Radio receiver to the 92 transmitter.

• Port 1: 145.17 (TX/RX)
• Port 2: 444.050 (RX)
• Port 3: Control Radio (TX/RX, half-duplex)

The EOC site is slightly more complicated than the other DCARA sites. In a default state, the Control Radio receiver is linked to the 17 and 050 transmitters to allow NOAA audio from the 146.92 site to be multicasted across these repeaters.

Linking Example (link 17 and 92 repeater):

1. Disable Hot Standby. By default the Control Radio receiver is linked to the 050 transmitter and 220 repeater for the “Hot Standby” function. This will prevent 92 receive audio from being routed to other transmitters.
2. Link 17 & Control Radio. This will route audio from the Control Radio receiver to the 17 transmitter and vice-versa.
3. Link 92 & Control Radio. This will route audio from the Control Radio receiver to the 92 transmitter and vice-versa.

Unlinking Example (unlink 17 and 92 repeater):

1. Unlink 92 & Control Radio
2. Unlink 17 & Control Radio
3. Enable Hot Standby. This re-establishes the NOAA audio link from the 92 site to the other sites.