Picture tour of the Tri-Town 146.805(-) 107.2PL 2-Meter Repeater
By Brian, WD9HSY
Welcome to the repeater!
I’ll be passing along credit to the rest of the repeater guys that have helped keep this little monster up and running and were instrumental in putting it up and on the air.
Let’s start at the top!
The repeater uses a Decibel Products DB222 2-Bay Folded Dipole antenna. This is a commercial-grade antenna, not a lightweight Ham-grade antenna.
We have ½ inch Hardline coming from the antenna to this copper plate grounding block. The grounding cable and PolyPhaser are mounted here as well as the cabinet ground wire. From here there is a piece of ¼ inch hardline going into the cabinet and the duplexers.
AC Power Conditioning
Dan, WB9ACN (SK) provided AC / lightning protection for the machine. This is the protection from lightning (PolyPhaser) and AC power surges. (Blue Thing!…. Hi-Tech terminology)
Inside the cabinet!
The Radio, Duplexers, and Controller
The cabinet is dark and cramped with wires here and there. The repeater consists of the Motorola Micor radio, power supply, repeater controller, and duplexer. The picture shows the general layout. I have a fan blowing across the heatsink of the Micor that is above and out of the picture. This is the back view (working end) of the cabinet.
It’s a little hard to see, but that shiny thing under the Motorola Micor is the SCOM 7K repeater controller. It’s the heart of the system. This part controls the IDs, timers, announcements, autopatch, voice announcements, and all the courtesy beeps. It gives the system its “personality.” If you have timed out the repeater, the 7K got you! The last time I checked I had about 4-5 pages of programming for the 7K. It is programmed over the air or by the telephone using DTMF tones. As an example I have to type this in to get the 7K to say, “This is the WD9HSY repeater”:
MPW 20 9000 MPW 15 9981 9988 9989 9985 9960 0565 0101 0335 0207 0431 0587 0377 0421*
The Power Supply
This is a 40-amp power supply made from Motorola parts by Mike, WA9ZPM. This power supply has been running 24 hrs, 7 days a week, since the repeater went on the air, more than 20 years ago. Mike wins another “Show and Tell” contest with this power supply. I have a feeling this supply will still be here for 20+ years or more! Thanks, Mike!
Pre-amp and Duplexers
This is a tight shot of the duplexers and the Pre-amp. The duplexers are the “Black Box” of repeater operations. These 4 “tanks” are mechanical filters that tune to the receive and transmit freq. and allow the radio to transmit and receive at the same time. This prevents the transmitter from swamping the receiver. The preamp goes from the duplexers to the Motorola Micor and gives a boost to the incoming weak incoming signal. Over the years we have had the preamp in and out of the system. Currently, it’s out of the system and the Micor is running on its own.