Note: groups.io will be down for maintenance on Wednesday, October 5th, starting at 9AM Pacific Time (4PM Wednesday October 5, 2022 UTC), for approximately one hour.
Some good ideas here. Note, I have more than enough speed to run Fldigi and WSJT-X with the zero 2...no issues with that and I think there is some excess capability, which is why I was thinking of "underclocking". I had run the original Pi-zero overclocked about 10%, but never had any heat issues.
The Swap file only gets to about 70%, as does memory usage in the worst case and usually less. CPU usage is below 40%. The only issue has been heat buildup and shutdown, and only when running Fldigi. I can delay it by leaving the top off the small case, but as room temps rise into the 70's even that is not enough. I just checked and the "slow CPU" option was automatically selected on the 4.1.01 version I am using. The diplay is optimized for the little 8" display on the Kindle Fire I am using to interface with the Pi. Bluetooth is off, but the WiFi is a critical part as the unit is running headless and linking to a simple tablet in the field, even out of WiFi range using it as a hotspot.
Is there a heatsink somewhere that is the same size as the whole Pi-zero that could substitute for the plastic top of the Vilros mini-case or something similar? That roughly 800% increase in surface might do the job.