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  • Case ID: 119173
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Problem with radio frequency custom board. Balun mismatch?

angel

Hi Nordic,

I have an application that perfectly runs in the nrf51DK but that does not work in my custom board. In my custom board everything else works (i2c, leds lighting, etc..) except for the communication related stuff. I think I am having some problems with the antenna. The balun I am using is 2450BM08B0003, which is the one recommended in this page for the nrf51422. As a detail, the components in the board have been placed by hand and soldered with oven reflow.

Here I attach the parts of the design that have to do with the communication.

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Any idea on how to debug my problem? I have no idea what is going on. I have been reading some other people have the exact same problem, but I have yet no idea of a proper solution.

PS: Sometimes we can transmit data from our custom board to the nordic developer kit. But not the other way around, we cannot receive data. Is this usual?

Thanks for your help!

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  • 0

    Alright, it should not be the LFCLK then. Could you describe how you tested the TX and RX? i.e what kind of device did you measure with or test against? Did you enable the DCDC converter when testing(if so, try disabling it)? Also what is C_L for the 16 MHz crystal in your custom board?

  • 0 in reply to Andreas

    Thanks a lot Andreas, in the end we finally found the problem thanks to your last message :). We had changed the 16MHz capacitors to a slightly smaller value (8pF instead of 12pF) to try to solve the problem, and then we forgot to change them back once we had the correct balun. Then we tried to put them again to 12pF and it worked!

    Now we have the problem of the range of the antenna, which is significantly smaller than the ones in the DK, but this we will solve tuning the antenna.

    Thanks a lot!

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  • 0 in reply to Andreas

    Thanks a lot Andreas, in the end we finally found the problem thanks to your last message :). We had changed the 16MHz capacitors to a slightly smaller value (8pF instead of 12pF) to try to solve the problem, and then we forgot to change them back once we had the correct balun. Then we tried to put them again to 12pF and it worked!

    Now we have the problem of the range of the antenna, which is significantly smaller than the ones in the DK, but this we will solve tuning the antenna.

    Thanks a lot!

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