Loopback test failed

Hello Everybody,

We tested lime mini on fedora.
Installed everything per the guide.

The RF test tx2 has strange dBFS : around -70. All the times it gives around minus 60-70.
The test does not pass. It fails over and over, without antenna.
Do you want screenshots? I have.
All other tests are fine. And tx 1 has around -15dbFS.

Any hints?
Firmwarare, or the hardware is broken?


Share log file please.


Usually it’s between -60 and -70.

Do you want more details?

It looks like TX_2 to LNA_W loopback path is damaged. Contact CrowdSupply for RMA.


Apologies for reviving a very old post, but I faced an interestingly-enough behaviour the community may benefit from hearing about.

Using Lime SDR Mini V2 with USB 2.0 ports replicate the behaviour of TX_2 LNA_W test failing, i.e. connection to USB 3.0 makes it pass.

More info:

In all cases I was using LimeSuite Rel 23.10.0

On a laptop running Ubuntu 20 (64bit ofc, Toshiba something, USB PORT 3.0) and the LimeSDR Mini v2 connected to two “normal” GSM/WCDMA/LTE omni antennas w/ magnetic mount:
Board tests pass O.K. (in particular TX_2 LNA_W passes)

Nevertheless, connected to a USB 2.0 Female adapter that splits in Y into two USB 3.0 Male terminals, one of them connected to a power source, the other one to a 3.0 USB Female port in a Raspberry pi 4B that uses the same LimeSuite version (23.10.0), the TX_2 LNA_W Test fails, but the rest of them pass.

Naturally the last test to share is the case where, albeit Lime SDR Mini v2 will/may have less power available, it’s directly connected to the Raspberry Pi 4B USB 3.0 Female port.
In this case tests are passed.


Thanks for sharing. Some comments:

In case of issues we always state that LimeQuickTest should be run with the board:

  1. Cold. I.e. not having been powered up for some time.
  2. With nothing connected to the RF ports.
  3. With the board plugged directly into a USB 3.x port.

If any of the above criteria are not met, all bets are off. Loopback test criteria are set for a cold board and performance will decrease slightly with temperature increases. Anything connected to RF ports could impact the test results. Connection to a USB 2.0 port and/or use of a problematic cable could result in power supply issues.

Right, but nothing should be cabled to the RG ports!

I’m not sure if in this scenario it would still only negotiate USB 2.0 power limits. A colleague could likely confirm.

But in this scenario it has all the USB 3.0 pins connected and presumably can negotiate increased power.

@Zack perhaps you could confirm.