LimeSDR Mini Very Hot on Idle


I have been attempting to get my LimeSDR Mini working. I was originally using a windows machine with PothoSDR (as recommended here). I was experiencing the dreaded “Loop-back Test Intermittent Failure Issue”.

Swapping over to a brand-new Raspberry Pi 4 with the latest 32-bit Raspberry Pi OS build (May 2020), I built the latest (at time of writing) LimeSuite from the git source on the advice here. (I moved to this setup because I find building source on Windows a road to insanity).

It worked! Now, still on the RPi, my SDR is working but running very hot. I left it idling (plugged into the USB, RPi powered on, no software running) for an hour and the temperature climbed up to 65+ C. This seems excessive. Can this be ignored or should this be addressed?

I am using a USB 3.0 ports on the RPi with a USB extension cable.


There is an unpopulated header for a fan on the board. Its advisable to use it. I use a 40mm fan directly over the chips. You can get problems running it without this.

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This is a good idea and I will probably implement this. I’m just concerned that that the excessive temperatures are an indicator that the SDR was damaged in some way by the original, defective, firmware. It seems very odd for a product to ship which on idle holds a steady temperature which will burn anyone that touches it.

My experience is that the Lime Mini needs to be cooled.

I put each Lime Mini in a metal case with heat transfer material between the PCB and the case, then a thermo-electric cooler to the outside of the metal case with a 70mm CPU heatsink + fan on the cooler.

A fan would probably do the job but the thermo-electric cooler ensures a stable temperature.

This is a very hot board. I’m kinda shocked that it is shipped without even some basic heatsinks on it. I can recommend this case for it. Cheaper than the “stock” aluminium case option that is available, and I dont even think the “stock” one has any contact with the chips to actually sink the heat away. With that hacker gadgets case, I initially tried to use it without the fan, not wanting a fan and the extra nose from it, but that entire case gets extremely warm without the fan, so I did end up putting the fan on it. If the case without fan gets that warm, those chips have to be cooking themselves to death with no heat sinking what so ever.

I added a thermal pad under the screening box as in this post.

[LimeSDR mini thermal pad]


I think I will buy one of the cases recommended by d0ug though the thermal pad is a good idea, having the Lime fully enclosed seems sensible for when I inevitably drop it.

Unfortunately, I am still without an answer to my original question: could the temperatures I’m seeing be the result of the faulty firmware I initially flashed?

I wouldn’t have thought so, but pinging @Zack for comment also.

Do not think so.
I would recommend to use a fan, as @ultrajv mentioned above.

Ok. Thank’s for clarifying.
Thanks all for your input.
[RESOLVED] - (not sure how to mark the thread as such)