eHam
eHam Forums => Microcontrollers for Ham Radio (Arduino, Raspberry Pi, etc.) => Topic started by: KG0BA on August 25, 2021, 07:10:26 AM
-
I've built a couple of MMDVM hot spots lately, and noticed that on one of the two, the temperature runs around 122 F degrees, and the background color of the temperature window in the Dashboard Configuration Page of the software changes from green to yellowish orange when it approaches that temperature range, I guess to indicate that the temperature of the Pi-Zero is heading toward a temperature range that could damage it.
It's running around 115F degrees now, after having it on for about an hour. But, if I leave it running throughout the day, or have a QSO is when I notice the Pi-Zero hitting the higher temperature.
I've read where the internal clock speeds designed into the Pi are such that the Pi can reach temperatures of 185F degrees before damage occurs, and that the software for the Pi throttles back the clock speed to bring the temperature down away from the danger zone when temperatures start to gets up there.
The cases these MMDVM hot spots come with are aluminum and air cooled with vents in the side of the cases, and I've read where some do not recommend a heat sink be installed on the Pi zero chip because most of the heat syncs are supplied and applied with regular double stick tape, and those that have tested after applying the heat syncs find that they only decrease the temperatures a couple of degrees.
I suppose that I could install a fan to assist in cooling, but it would be a pain, as none of the cases for the footprint of the Pi-Zero seem to be supplied with a fan option, and there are power constraints as well with respect to powering a fan and the Pi-Zero together. I could also install a heat sync using proper chip adhesive or proper heat sync tape, which I assume would be more effective than regular double stick tape.
But, at the temperatures being displayed, and the seemingly relatively stable temperatures not moving up any further as the hot spot is operating, I'm not sure my concerns are even valid with respect to the temperature range in the 120's F being an issue. Advice?
-
I put both of my hotspots back on the air a few weeks ago and since my shack lacks AC....both have been hovering around 134 to 145 degrees at all times. They run 24/7. I'm also running Pi 3B+ units.
The problem with cooling is that the MMDVM boards will get in the way. They don't leave a lot of room for airflow. Even if you put a fan on there, it will probably be right up against the board. This is even worse if you have a full duplex HAT which is about the same size as a full RPi. None of the standard cases are designed to accommodate the MMDVM hats.