Unsupressed Carrier on SSB

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  • Updated 4 years ago
I have reports of a slight carrier when operating on SSB.  Checked my second rig and sure enough, it's there.  I'm running a Flex 6300, SSDR 1.4.16.142 under Windows 8.1.  The locals who have reported it say that this is something new, perhaps with the latest release of SSDR.
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Bill Roberts

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Posted 4 years ago

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Jon - KF2E

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Just a thought but could you have a hum in your mic that is causing the slight carrier? Maybe a grounding or shield issue?

Jon...kf2e
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David Decoons wo2x, Elmer

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Either hum or the 20 dB boost is on and he's picking up some kind of background noise. Simple enough to test. Unplug mic and click MOX. No carrier then it is mic picking up noise or hum and not a carrier supression issue.

Dave wo2x
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Tim - W4TME, Customer Experience Manager

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This is an excellent troubleshooting suggestion.  Let us know the results of this test.
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Bill Roberts

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Actually, when you disconnect the microphone line the noise gets worse: louder and more raw.  My radio is SN 3114-4046-6300-7997.  It had to go back to Austin for installation of a component to eliminate echo in the transmitted audio.  The transmitted noise (with microphone disconnected) sounds like noise from one of the internal fans is being induced into the audio.  Is this possible?
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Ken - NM9P, Elmer

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How wide is your TX bandwidth on the low end?  I cut mine off at 65 Hz so that it will block much of any 60 Hz hum that I may have induced by stuff in the shack.  So far it has kept things clean. 
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Barry N1EU

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If you're using any external audio equipment between the mic and 6300, you might have a ground loop causing the issue.

Barry N1EU
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Tim - W4TME, Customer Experience Manager

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Official Response
I have converted this topic to a support HelpDesk ticket (http://helpdesk.flexradio.com) for expedited issue resolution.  If anyone else is experiencing an issue similar to this one, please submit a HelpDesk support ticket for issue resolution.
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W7NGA

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Just looking at the panadapter display I can see some residual carrier on SSB. Quite reduced but I suspect someone local might hear it as they would from any transmitter. Also, the Low Cut setting should be checked. When set to 0, noise and modulation products approach the carrier frequency. I just returned from Asia and am setting up the lab once again. I know there are several spectrum analyzers around here somewhere and I wouldn't mind taking the time to look into this at greater depth. I am sure it is well within the specification (-80 dBc).

W7NGA  dan
San Juan Island, Wa.
(Edited)
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Bill Roberts

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Yes, I noticed that setting the transmit low frequency cutoff to 50 did cause additional products to make it onto the display.  I have since set it t0 200 Hz.

I'll contact the Help Desk.  Thanks