Some friends and I recently placed a Kenwood TH-D72 on the summit of Saddle Mountain in Oregon, USA, and set it up as a temporary digipeater for use with APRS.
The TH-D72 successfully digipeated packets, but when our hiker summited the mountain again the next day, he found that TH-D72 was stuck on the startup splash screen and was unresponsive to any button presses (other than powering off).
I haven’t been able to find any reports of a TH-D72 freezing on the startup splash screen. Does anyone have experience with this? What is a likely cause of this behavior? We haven't seen the TH-D72 freeze on the splash screen before or since.
The sequence of events is roughly as follows:
2017-08-25 15:10:33 - Hiker sets up TH-D72 and manually sends first APRS beacon. 2017-08-25 16:30:00 - Hiker descends mountain and leaves TH-72 on summit. 2017-08-25 19:15:44 - First vehicle comes in range and TH-D72 digipeats an APRS position packet. 2017-08-26 05:09:17 - Final digipeated APRS packet (all vehicles may have gone out of range at this point). 2017-08-26 06:54:40 - Final automatic APRS beacon sent from TH-D72 (it seems to have sent beacons up to 00:30:00 apart). 2017-08-26 07:45:40 - Hiker summits mountain again and finds TH-D72 stuck on the startup splash screen.
The radio was powered by YUASA NP7-12 12V,7.0h battery and 12V to 7.5V switching regulator. The battery manufacturer recommends keeping the battery between –15°C and +50°C for charging and discharging. The temperature on the summit was likely between 4°C and 32°C. The enclosure was vented with a fan.
Two days after the hiker retrieved the enclosure with the radio and battery, we started up the TH-D72 and it successfully sent several APRS beacons. It did not freeze up. The voltage droop during packet transmission was minimal: