Topcon GR3 Troubleshooting Questions

What type of radio modems are in the GR-3 units??ÿ In the US, they'd either but UHF or 915 MHz spread spectrum modems.?ÿ The easy way to distinguish between them is how the radio antennas connect to the receiver.?ÿ UHF modem had BNC connectors, characteristically having to knobs on opposites sides of the connector and slots in the portion of the antenna that is attached to the connector.?ÿ Will be secured to the connector with a quarter-turn rotation.?ÿ The spread spectrum 915 MHz connector have TNC connectors, so the that antenna threads onto the connector.

If you have receivers equipped with UHF modems, the condition you describe could be caused by radio interference.?ÿ A simple solution to the problem is to change radio channels, which you should be able to do through Survey Pro in the Modem settings.

Looking at your profile, I see you are in Canada.?ÿ I know nothing about the modems approved for use there.?ÿ I believe we've sent GNSS receivers to folks in Canada that were equipped with UHF radios but I cannot say for certain.

Agree with @jerrys - first check for interference, then antenna connection issues.

If none of that works, it might be worth sending it to the dealer/service shop to have them check the radio module.

This is anecdotal, but I know of a few folks running Topcon base/rover who had the radio modules simply stop working out of the blue, across their entire equipment fleet. While random radio failure does happen across all manufacturers, there were a few model years of Topcon that seemed particularly prone to this issue.