Distorted FT8

Steve N4GXX · July 2021

I have a 6600 with ver 3.2.39 firmware/SmartSDR S/W. Running the latest version of WSJT-X ver 2.4.0 Ever since I got the 6600 I have noticed "Birdies" above and below the main signal. I have been wondering it this was going out over the air. Today a Ham on the north side of town, about 4 miles from me. sent me a picture of my siginal and yup my signal is in fact dirty.
Setting are:
WSJT-X TV level at -6 or lower.
DAX at 55 for about 80 watts out.

The attached picture is what I see. I see that distortion all the way down to around 5 - 10 watts out.

Anyone have any thoughts before I open a ticket?

Thanks
Steve N4GXX

David Decoons, wo2x · July 2021

I cannot open your attachment.

Make sure the peak level indicator is not going red (above zero). It should be yellow at highest. Set WSJT-X power slider all the way up and set DAX TX to 48. That will set proper output level.

You may see the "birdies" as you described them on the panadapter during TX but unless you are using full duplex and monitoring your signal on an actual receiver what you see may not be going out.

As far as your friend, how strong are you to him? If around +25 then you can potentially be overloading his front end and causing him to see stuff that might not be an issue.

If using a solid state amp you can expect the 3rd order IMD to only be down about 30 to 35dB at best.

73 Dave wo2x

Steve N4GXX · July 2021

A: He had me on the back side of his 6 Mtr beam at the time. B: He put 20dB of attenuation in line with no change. I see the same thing on my panadapter at the same spacing. I at around the -6dB mark on my input (the yellow bar). I am also seeing trash on a dead carrier into a dummy load.

Mike-VA3MW · July 2021

Please handle this via a support ticket if you are not doing so already. Thanks

Distorted FT8

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