The Portland to Salem Connection

What to do once your clubs' ATV repeater is up and running?  How about trying to expand your user base. What is the best way to gather more users? In Portland we looked at connecting our repeater to another ATV repeater, making either repeater accessable from the other. With the cooperation of fellow ATV'ers in Salem Oregons' SATVA; in early 1999 we began working toward a reliable link between the two cities.

Our first tests proved the Portland ATV repeater could be received 40 miles away at the Salem ATV repeater site. The decision was made to make that one half to the two way linking system. The Portland repeaters signal would be received at Salem and retransmitted on the Salem ATV repeater. For the opposite direction we chose to go with a 2.4 GHz ATV signal transmitting the Salem ATV repeater signal north to Portland.

The transmitter and receiver for the 2.4 GHz video link were purchased from HF Technologies. The antennas at both sites for 2.4 GHz were 3 foot rectangular wire grid parabolic dishes with feeds. Initial testing of the 2.4 GHz video signal showed a need for power greater than 1 watt, so a 10 watt amplifier was added to the Salem linking transmitter. The received video from Salem is routed to one port of the Lloyd I-O prototype video controller and may be switched on when desired.

Since the Video link was established we have also transmitted signals using modified Wavecom 2.4 GHz transmitter and receiver. The modificatiions are installing a connector for an external antenna, selecting frequencies in the Amateur Radio Band, and placing the equipment in a box compatible with our repeaters equipment shelving. This type of equipment also provided good signals, but care must be taken to have matching frequencies at each end. The consumer grade equipment operates on slightly different frequencies than the Amateur equipment. Although the signals can be received on mixed equipment, we find better results when the frequencies match exactly.

Of course, operating on 2.4 GHz requires care in locating equipment to limit the length of cabling needed. Our link receive antenna is located about 20' from the ATV repeater and the Link receiver. We made this connection with ordinary coax and have no signal problems. The configuration of our repeater helps us here as the equipment is installed on a deck at the 375' level of the tower, which is on the top of a 1000' high hill.

Not everything fell into place with this installation. We had problems with new gear which failed to work at all, we lost time troubleshooting problems on both ends of the video link and trying substitute equipment to isolate troubles. The end result is that we now have ATV nets with participants from both cities and find the signals equal to local stations. It has been a learning experience for all involved and we have new capabilities. It is worth thinking about for your ATV system.