LimeSDR quick test fail after temp increases, hopefully board is actually OK?

[zodiac-tiger]

Okay, so another potential quick test issue.

I bought a second LimeSDR (not mini) after my first board’s micro-b connector was damaged. When I received my new board a couple of months ago and I was careful to quickly check it for functionality and put it away until I had a suitable enclosure.

I just received my active cooling enclosure from crowd supply (Hacker Gadgets) a few days ago. Assembly for the enclosure required attaching the 12 u.fl cables and applying thermal paste to several components, but I was very careful. Everything seemed fine, until today when I ran the quick test.

When I first plug the Lime in, it passes with the following…

`->Start time: Sat May 2 21:37:44 2020

->Device: LimeSDR-USB, media=USB 3.0, module=FX3, addr=1d50:6108, serial=0009081C05C40F11
Serial Number: 0009081C05C40F11

[ Clock Network Test ]
->FX3 GPIF clock test
Test results: 60547; 64303; 2523 - 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 : 5112938 (min); 5113082 (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:(-14.2 dBFS, 5.00 MHz) - PASSED
CH1 (SXR=800.0MHz, SXT=805.0MHz): Result:(-16.0 dBFS, 5.00 MHz) - PASSED
->Run Tests (TX_1 -> LNA_W):
CH0 (SXR=1800.0MHz, SXT=1805.0MHz): Result:(-18.9 dBFS, 5.00 MHz) - PASSED
CH1 (SXR=1800.0MHz, SXT=1805.0MHz): Result:(-21.0 dBFS, 5.00 MHz) - PASSED
->Run Tests (TX_2-> LNA_H):
CH0 (SXR=2500.0MHz, SXT=2505.0MHz): Result:(-15.7 dBFS, 5.00 MHz) - PASSED
CH1 (SXR=2500.0MHz, SXT=2505.0MHz): Result:(-13.8 dBFS, 5.00 MHz) - PASSED
->RF Loopback Test PASSED

=> Board tests PASSED <=

Elapsed time: 2.03 seconds

However, as the temp increases the failure begins.

`[ TESTING STARTED ]
->Start time: Sat May 2 21:55:25 2020

->Device: LimeSDR-USB, media=USB 3.0, module=FX3, addr=1d50:6108, serial=0009081C05C40F11
Serial Number: 0009081C05C40F11

[ Clock Network Test ]
->FX3 GPIF clock test
Test results: 59662; 63418; 1638 - 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 : 5112948 (min); 5113089 (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:(-14.8 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:(-19.8 dBFS, 5.00 MHz) - PASSED
CH1 (SXR=1800.0MHz, SXT=1805.0MHz): Result:(-22.5 dBFS, 5.00 MHz) - FAILED
->Run Tests (TX_2-> LNA_H):
CH0 (SXR=2500.0MHz, SXT=2505.0MHz): Result:(-16.4 dBFS, 5.00 MHz) - PASSED
CH1 (SXR=2500.0MHz, SXT=2505.0MHz): Result:(-14.6 dBFS, 5.00 MHz) - PASSED
->RF Loopback Test FAILED

=> Board tests FAILED <=
``
The failure never surpasses about -22.6 dBFS and I’ve tested that RX2_W appears to be working with similar performance to RX1_W. I also noticed that several other people have had very similar failures with TX1->RX2_W specifically.

I guess I’m really hoping that my board is not truly damaged. I’m worried I may have trouble getting getting a replacement from Crowd Supply considering that it was purchased back in February.

Any thoughts?

[9a4db]

What is tenp. level?

[zodiac-tiger]

The case seems to be helping to control the temperature. It hovers in the 32 - 37 range while powered on, but not in use. Even under very heavy use it seems to fully max out at 52. I can’t even get the temperature high enough to trigger the fan to start running. The test seems to fail consistently once temperature reaches about 41.

However, I’m starting to think this is a false alarm. I read another post where Zack said the LimeQuick Test was meant to test cold boards, indicating that higher temperature would cause ‘false’ failures of the quick test.

[9a4db]

Tnx, I am trying to keep all my lime boards whole time bellow 45 C even
under hi loads.
That about false alarm is possible too.

[d0ug]

I Also have one of the hacker gadgets cases for my lime mini. I had a similar issue with one of the tests reporting failure after putting the lime mini into the case. Id take it out of the case and it would pass. Double checked and could not see where anything with the case appeared to be causing any electrical shorts. I found that with the screws torqued all the way down the failures would happen, if I backed the screws off about half a turn the board would pass. The only assumption I can make is the thermal pad might be putting stress on the board changing something electrically?

[andrewback]

As suggested by others the self-test should only ever be run when the board is cold, with nothing attached to the RF ports and probably ideally not fitted in a case — impossible to say how pressure on the board and adjacent metalwork etc. might affect results.

Also, hopefully it’s a one off, but we haven’t tested the Hacker Gadgets cases and obviously cannot vouch for third party products anyway, but it is possible that thermal coupling may not be great and if so, this might not help either.

Tetra A case for LimeSDR-A : JUNK!

I received a Lime SDR Type-A and Tetra A case to “protect” it. The case claims to be CNC made but does not resemble that type of quality at all. The holes for the sma connectors were way oversize and the provided connectors spun even though the case had flat spots. Due to the instructions to tangle and fold the all identically sized pigtails causes the lime to fail the self test due to poor signal quality. I had -21 dbm fail on one of the last freq checks. (I have a somewhat related photo inclu…

Although you note that it does seem to be keeping the temperature down, which is good, and the other report regarding the case will hopefully be a one-off QC issue.

[d0ug]

I would think depending on the application, the identically lengthed pigtails would be ideal. You should be getting the same predictable loss due to the pigtails across all ports. Also different length pigtails would throw off signal timing depending on how exacting your needs are for them to be synchronized.

[andrewback]

There should not be anything connected to the RF ports when running LimeQuickTest. This uses internal loopback and antennas or cables connected to ports will add unknown variables.

[zodiac-tiger]

My board passes all tests consistently when cold, so I’m convinced my concern about this issue was misguided. As usual when using USB 3.0 I have ALOT more overall noise to deal with, but I’ve come to conclude this is due to interference from the increased power and/or ,perhaps, a less-than-ideal usb 3.0 cable. That is a problem I’ve dealt with across 2 full size and 2 mini LimeSDR’s.

It troubles me that grimmace has had such a poor experience with the Hacker Gadget’s Tetra AC case. His review was pretty scathing. I don’t have much experience with SDR enclosures, or cooling systems in general so I don’t know if I’m overlooking flaws in the Tetra AC case I received. However, mine seems to fit rather perfectly, and the heat sinks seem to make good contact with the chips and the thermal paste. I can’t even get the board hot enough to test the fan. I do have the same exact problematic results with the WCDMA self test though. Although, I didn’t do the test prior to putting the board in the enclosure. At this point, I probably won’t remove the board unless something really prompts me to. Unfortunately, I do have a bit of trouble with the SMA port holes being ever so slightly oversized. Causing the dreaded spin. Anyone got any quick hacks to fix that? Maybe some type of glue?

To grimmace or anyone interested, if you have any questions about the Tetra AC case for the full-size LimeSDR, I’ll try to answer based on the one I received.

Thanks for all the replies, my mind is at ease…Except.

Andrew, why doesn’t Lime sell any Aluminum enclosures without having to buy in a kit?

[Grimmace]

Hey @zodiac-tiger I just noticed the mention from 2 weeks ago. I have not reworked my Tetra A case yet. I’m still just listening. I have not had any heat issues yet but still need to replace the paste with pads due to the gap. I have not noticed my Lime go above 46 degrees yet but I’m only using one rx and tune the LNAs low enough to receive my target.

USB 3 is known to cause a lot of radio interference. I put, on the end near the Lime, two loops through a large half inch snap on ferrite magnetic bead. I should try a before and after for comparison but I know that will help a lot with noise. More loops would be even better. I’ve actually isolated the Lime in a closet on the other side of the wall were I keep dropping more coax from the attic. Good grounding may help too. I’m not sure if it could cause any USB troubles though, presumably not as the cable is shielded already. I’ve even discovered that radio dongles like Logitech unified receiver etc seem to work better on USB 2 connections.