# LimeSDR TX output harmonics

**URL:** <https://discourse.myriadrf.org/t/limesdr-tx-output-harmonics/6724>\
**Category:** LimeSDR\
**Created:** [23 November 2020 16:26 UTC](https://discourse.myriadrf.org/t/limesdr-tx-output-harmonics/6724 "2020-11-23T16:26:53Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![manuelpreu](https://avatars.discourse-cdn.com/v4/letter/m/76d3ee/32.png) [@manuelpreu](https://discourse.myriadrf.org/u/manuelpreu)\
**Post date:** [23 November 2020 16:26 UTC](https://discourse.myriadrf.org/t/limesdr-tx-output-harmonics/6724/1 "2020-11-23T16:26:53Z")

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I need only the LO frequency with maximum output power for a project. So if i stream ones with the SopaySDR writeStream() to the LMS I get big output harmonics when the LO frequency is set to below 100MHz. Does this imply that the default TX1\_1 matching network is not matching the 40Ohm differential? Or is there another known issue? The harmonics don´t change relatively to the fundamental if the TX gain is changed.

Thank you in advance.  
Best regards,  
Manuel

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**Author:** ![Crater](https://avatars.discourse-cdn.com/v4/letter/c/58f4c7/32.png) [@Crater](https://discourse.myriadrf.org/u/Crater)\
**Post date:** [24 November 2020 06:21 UTC](https://discourse.myriadrf.org/t/limesdr-tx-output-harmonics/6724/2 "2020-11-24T06:21:51Z")

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I made some measurements some time ago:  
Here they are:[S11 Measurement Results](https://discourse.myriadrf.org/t/s11-measurement-results/5463)  
In Short: There isn’t any matching below 2 GHz.