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Hi! I recently posted about having some bad reception on my qmx after updating the firmware... Well it seems that it is something related to the hardware of my unit.

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I checked the RF filter sweep and it seems that my unit became a bit deaf.

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How should I proceed from here? What tests should I do?

This unit was working before, so my guess its that I messed up something?

This tests results are after a fresh firmware install and a factory reset.

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Thanks in advance!

73 de EA4IIF.

Hi Hector,

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alle the values are much to low, around -40 dB for the (real) peaks. It looks like a bad connection in the RX path. Please check solder joint of L401 towards IC402 pin9 for QMX Rev. 1 or towards "RX_IN" for later revisions.

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73 Ludwig

Thanks for the reply! Could the solder joint have gone bad on its own? As I stated, it was working perfectly fine until about 1-2 weeks ago. I'll test it this evening though

Also check that it is still set to the correct band version in system settings?

On Fri, Apr 4, 2025 at 04:47 PM, H EA4IIF wrote:

Could the solder joint have gone bad on its own?

Yes, by time, by changing temperature or after some mechanical pressure.

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And check please also solder joint from T401 towards IC402 pin 7 for QMX Rev. 1 or pin 9 for later revisions.

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73 Ludwig

So as @Ludwig_DH8WN pointed out, I checked the soldering of the L401, there were some toroid soldering points that were not making good contacts. After soldering them well, the measures are of around -10 to -18dB. Thanks to y'all for the help!?

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Now the unit works as expected I even managed to make a QSO with the new SSB firmware!?

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Thanks again for the help pointing out where to check!

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73 de EA4IIF.