Black square plastic element with "GU" indication on top

Hi there,

Unfortunately, while mounting one of my LimeSDR boards in Luftek’s enclosure I have accedentally detached thin black square plastic element with “GU” indication on top of it. I can see such elements placed near matching networks for all high frequency TX/RX ports.

Since I am not good at electronics, I would like to ask you to describe what is its function and is it critical for it to be in that place? How, if at all, is it going to affect performance of RX2_H port? Is it safe if I simply use some fast glue to make sure it won’t pop out again?

Thanks in advance for your help!

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It’s most likely some pad to aid pick and place process and/or some shielding element on RF transformer. It’s not critical. I lost one to.

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Looking at I would guess that it is one of the RF input transformers. Looking at page 6 of the schematic the part for RX2_H would be T9 a TCM1-63AX+, and by removing it, you have no signal path. Do not use glue!

P.S. A photo of the board would help in advising what the exact fault is and the best course of action to rectify it.

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If only “hat” is removed and all wires are still in tact everything should work fine.

Yes, only this “hat” has been removed. Nevertheless, is was there for some reason, I am just curious what it is :stuck_out_tongue:

Following photos show exactly problematic element (second photo shows another board where hat is in right place):

Totally different than what I was expecting. My suspicion is that it may just be cosmetic, but I don’t know. I’d leave it as is, if it was my board, and compare the performance of RX2_H to RX1_H, taking screen shots of each with the same settings.

It is for Pick & Place machine when assembling. If the wires are not cut and everything else of this component is in place then it should be OK.

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Oh, I see. What a relief :slight_smile: Thank you all for your help!