Not-Quite-So-Hot Stuff: A Thermal Exam On The Latest Raspberry Pi

When the Raspberry Pi 4 was first launched, one of its few perceived flaws was that it had a propensity to get extremely hot. It’s evidently something the Pi people take very seriously, so in the months since they have addressed the problem with a set of firmware updates. Now they’ve taken a look at the effect of the fixes in a piece on the Raspberry Pi web site, and it makes for an interesting comparison.

The headline figure is that all updates together remove about a watt of power from the load, a significant quantity for what is still a board that can run from a capable phone charger. Breaking down the separate parts of the updates is where the meat of this story lies though, as we see the individual effects of the various USB, memory, power management and clocking updates. In temperature terms they measure an on-load drop from 72.1 °C to 58.1 °C, which should be a significant improvement for any Pi 4 owner.

There is a debate to be had over in what role a computer such as a Pi should serve. As successive revisions become ever more desktop-like in their capabilities, do they run the risk of abandoning the simplicity of a cheap Linux box as a component that makes us come back for more? It’s a possibility, but one they have very well addressed by developing the Pi Zero. They have also successfully avoided the fate of the Arduino — inexorably tied to its ATmega powered original line despite newer releases. As we have frequently said when reviewing Raspberry Pi competitors, it’s the software support that sets them apart from the herd, something this power-draw story demonstrates admirably.

Old Heatsink Lets Ham Push Duty Cycle For Digital Modes

Listen to the amateur radio bands long enough, and you’ll likely come to the conclusion that hams never stop talking. Of course it only seems that way, and the duty cycle for a transmitter operating in one of the voice modes is likely to be pretty low. But digital modes can up the duty cycle and really stress the finals on a rig, so this field-expedient heat sink for a ham transceiver is a handy trick to keep in mind.

This hacklet comes by way of [Kevin Loughin (KB9RLW)], who is trying to use his “shack-in-a-box” Yaesu FT-817 for digital modes like PSK31. Digital modes essentially turn the transceiver into a low-baud modem and thus messages can take a long time to send. This poses a problem for the 5-watt FT-817, which was designed for portable operations and doesn’t have the cooling fans and heavy heatsinks that a big base station rig does. [Kevin] found that an old 486 CPU heatsink clamped to a lug on the rear panel added enough thermal mass to keep the finals much cooler, even with a four-minute dead key into a dummy load at the radio’s full 5-watt output.

You may scoff at the simplicity of this solution, and we’ll concede that it’s far from an epic hack. But sometimes it’s the simple fixes that it pays to keep in mind. However, if your project needs a little less seat-of-the-pants and a little more engineering, be sure to check out [Bil Herd]’s primer on thermal management.
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