Guthrie 600 Repeater: Winter Site Visit, Repairs, and Programming Updates

Summary

We traveled to the Guthrie Peak site today, skirting the trailing edge of a winter storm, leaving Tucson at around 4:00am. The timing made for a memorable drive, with spectacular scenery on the way up – low clouds, fresh snow on the surrounding peaks, and the kind of quiet you only get at elevation when weather has left its mark.

Once on site, we addressed both RF performance and a network outage.

Repeater Programming Update

The Guthrie 600 repeater was reprogrammed to use split PL tones (separate transmit and receive tones). This change was implemented to help mitigate an ongoing intermodulation issue that persists despite a very thorough receive filtering setup. Check the programming page for updated information!

While high-quality cavity filtering is effective at rejecting out-of-band signals, intermod can still be generated within the receiver itself or the surrounding RF environment when multiple strong signals mix together – something that’s often difficult to completely eliminate at busy, high-RF mountaintop sites. Split tones reduce unintended access by requiring a more specific signaling match, helping prevent nuisance key-ups caused by intermod products that filtering alone can’t always resolve.

Network Repair

We also traced the repeater’s network outage to a severed fiber-optic connection between buildings. The damaged fiber was replaced during this visit, restoring network connectivity and returning the system to full operation.

Please Remember to Donate

We don’t require payment for memberships; we believe reliable communications should be available for all. If you use or rely on the Guthrie 600 repeater – or simply value having dependable coverage when conditions are less than ideal – and have a few bucks to toss in the pot, please consider donating. Your support directly offsets trips like this and helps keep the system reliable, resilient, and on the air year-round.