RF Loopback Test Failed

Hello - I have a newly purchased LimeSDR usb; I followed the installation and firmware/gateware updates without issue, but the RF Loopback Test consistently fails; can anyone diagnose the following?

[ TESTING STARTED ]
->Start time: Thu Sep 12 20:07:51 2019

->Device: LimeSDR-USB, media=USB 3.0, module=FX3, addr=1d50:6108, serial=00090726074D271A
Serial Number: 00090726074D271A

[ Clock Network Test ]
->FX3 GPIF clock test
Test results: 31826; 35582; 39338 - PASSED
->Si5351C test
CLK0: 17554 / 17554 - PASSED
CLK1: 17554 / 17554 - PASSED
CLK2: 17554 / 17554 - PASSED
CLK3: 17554 / 17554 - PASSED
CLK4: 17554 / 17554 - PASSED
CLK5: 17554 / 17554 - PASSED
CLK6: 17554 / 17554 - PASSED
->ADF4002 Test
Result: 10 - PASSED
->VCTCXO test
Results : 5112949 (min); 5113092 (max) - PASSED
->Clock Network Test PASSED

[ FPGA EEPROM Test ]
->Read EEPROM
->Read data: 12 0C 07 12 0C 07 02
->FPGA EEPROM Test PASSED

[ LMS7002M Test ]
->Perform Registers Test
->External Reset line test
Reg 0x20: Write value 0xFFFD, Read value 0xFFFD
Reg 0x20: value after reset 0x0FFFF
->LMS7002M Test PASSED

[ RF Loopback Test ]
Note: The test should be run without anything connected to RF ports
->Configure LMS
->Run Tests (TX_2-> LNA_L):
CH0 (SXR=800.0MHz, SXT=805.0MHz): Result:(-14.6 dBFS, 5.00 MHz) - PASSED
CH1 (SXR=800.0MHz, SXT=805.0MHz): Result:(-16.6 dBFS, 5.00 MHz) - PASSED
->Run Tests (TX_1 -> LNA_W):
CH0 (SXR=1800.0MHz, SXT=1805.0MHz): Result:(-18.0 dBFS, 5.00 MHz) - PASSED
CH1 (SXR=1800.0MHz, SXT=1805.0MHz): Result:(-27.3 dBFS, 5.00 MHz) - FAILED
->Run Tests (TX_2-> LNA_H):
CH0 (SXR=2500.0MHz, SXT=2505.0MHz): Result:(-19.2 dBFS, 5.00 MHz) - PASSED
CH1 (SXR=2500.0MHz, SXT=2505.0MHz): Result:(-15.9 dBFS, 5.00 MHz) - PASSED
->RF Loopback Test FAILED

=> Board tests FAILED <=

Elapsed time: 1.51 seconds

That was the original test; now it will not even get that far, with it unable to conduct the RF Loopback tests at all:

[ TESTING STARTED ]
->Start time: Thu Sep 12 20:46:15 2019

->Device: LimeSDR-USB, media=USB 3.0, module=FX3, addr=1d50:6108, serial=00090726074D271A
Serial Number: 00090726074D271A

[ Clock Network Test ]
->FX3 GPIF clock test
Test results: 19707; 23463; 27219 - PASSED
->Si5351C test
CLK0: 17555 / 17554 - PASSED
CLK1: 17555 / 17554 - PASSED
CLK2: 17555 / 17554 - PASSED
CLK3: 17555 / 17554 - PASSED
CLK4: 17555 / 17554 - PASSED
CLK5: 17555 / 17554 - PASSED
CLK6: 17555 / 17554 - PASSED
->ADF4002 Test
Result: 10 - PASSED
->VCTCXO test
Results : 5112952 (min); 5113094 (max) - PASSED
->Clock Network Test PASSED

[ FPGA EEPROM Test ]
->Read EEPROM
->Read data: 12 0C 07 12 0C 07 02
->FPGA EEPROM Test PASSED

[ LMS7002M Test ]
->Perform Registers Test
->External Reset line test
Reg 0x20: Write value 0xFFFD, Read value 0xFFFD
Reg 0x20: value after reset 0x0FFFF
->LMS7002M Test PASSED

[ RF Loopback Test ]
Note: The test should be run without anything connected to RF ports
->Configure LMS
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
LML TX phase search FAIL
Failed to set sample rate
->RF Loopback Test FAILED

=> Board tests FAILED <=

Elapsed time: 1.47 seconds

Any idea what could be going on?

Hi @Cedar,

Do you have something connected to RF ports during test?

Hi @Zack,

No, I have it in the aluminum case, but the antennae are removed.

Hi @Cedar,

Contact CS for RMA, please. Sorry for inconvenience.

@Zack I will contact them. Thank you for your time in evaluating this error.

I would like to contribute in discussion instead of creating a new topic.
Recently I did some measurements with LimeSDR and got all necessary data from antennas. Now I am encountering a problem with

Rx calibration: MCU error 5 (Loopback signal weak: not connected/insufficient gain?)

Ok, well, I just increased gain in my script, but this did not work

I have tried LimeSuiteGUI by pressing Defaults - Calibrate with temperature around 45 degrees, aaaaand… Same error

Then I have tried LimeQuicktest

LimeQuickTest
    [ TESTING STARTED ]
    ->Start time: Mon Jan 13 13:16:14 2020

    ->Device: LimeSDR-USB, media=USB 3.0, module=FX3, addr=1d50:6108, serial=0009081C05C32739
      Serial Number: 0009081C05C32739

    [ Clock Network Test ]
    ->FX3 GPIF clock test
      Test results: 16873; 20629; 24385 - PASSED
    ->Si5351C test
      CLK0: 17554 / 17554 - PASSED
      CLK1: 17554 / 17554 - PASSED
      CLK2: 17554 / 17554 - PASSED
      CLK3: 17554 / 17554 - PASSED
      CLK4: 17554 / 17554 - PASSED
      CLK5: 17554 / 17554 - PASSED
      CLK6: 17554 / 17554 - PASSED
    ->ADF4002 Test
      Result: 10 - PASSED
    ->VCTCXO test
      Results : 5112939 (min); 5113086 (max) - PASSED
    ->Clock Network Test PASSED

    [ FPGA EEPROM Test ]
    ->Read EEPROM
    ->Read data: 13 01 1D 13 01 1D 02
    ->FPGA EEPROM Test PASSED

    [ LMS7002M Test ]
    ->Perform Registers Test
    ->External Reset line test
      Reg 0x20: Write value 0xFFFD, Read value 0xFFFD
      Reg 0x20: value after reset 0x0FFFF
    ->LMS7002M Test PASSED

    [ RF Loopback Test ]
    Note: The test should be run without anything connected to RF ports
    ->Configure LMS
    ->Run Tests (TX_2-> LNA_L):
      CH0 (SXR=800.0MHz, SXT=805.0MHz): Result:(-68.5 dBFS, -10.00 MHz) - FAILED
      CH1 (SXR=800.0MHz, SXT=805.0MHz): Result:(-74.1 dBFS, -10.00 MHz) - FAILED
    ->Run Tests (TX_1 -> LNA_W):
      CH0 (SXR=1800.0MHz, SXT=1805.0MHz): Result:(-55.0 dBFS, -20.00 MHz) - FAILED
      CH1 (SXR=1800.0MHz, SXT=1805.0MHz): Result:(-53.6 dBFS, -20.00 MHz) - FAILED
    ->Run Tests (TX_2-> LNA_H):
      CH0 (SXR=2500.0MHz, SXT=2505.0MHz): Result:(-61.9 dBFS, 5.00 MHz) - FAILED
      CH1 (SXR=2500.0MHz, SXT=2505.0MHz): Result:(-56.3 dBFS, 5.00 MHz) - FAILED
    ->RF Loopback Test FAILED

    => Board tests FAILED <=

    Elapsed time: 1.57 seconds

I have no Idea at all which numbers have to be in the test, what does this test means and how can I head at least noise from my RX channels? I am not interested in transmitting at all

Any suggestions would be highly welcome

Best Wishes

Update, I switched Lime off and on from USB3 port and now encounter another error in LimeSuiteGUI

[13:39:06] INFO: Connected Control port: LimeSDR-USB FW:4 HW:4 Protocol:1 GW:2.21 Ref Clk: 30.72 MHz
[13:39:09] ERROR: Tx Calibration: MCU error 4 (SXT tune failed)

Hi @Skye,

As per note in the tester log:

The test should be run without anything connected to RF ports

Do you have something connected to the RF ports?

Hi Zack,
thanks for your quick reply.
There was just connector between Lime output and SMA, 10 cm wire. It was not connected to anything else.
I have also tried test without those wires, result is almost the same, difference is ±1 dBFS.

Hi @Skye,

Then, as I can see from RF Loopback test, all your RF inputs/outputs are damaged. Maybe RF matching network is damaged or LMS7002M itself. Try to inspect the board visually, especially RF area.

Hi Zack,
Ok, thanks, I will take a look, but visually there are no damage evidences, maybe microscope could help.

I have tried another LimeSDR, it passes LimeQuickTest, but still generates
[14:08:00] ERROR: Tx Calibration: MCU error 5 (Loopback signal weak: not connected/insufficient gain?)
Nothing is connected to its ports