Slight audio distortion on 40 meters

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  • Updated 3 years ago
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Purchaced a Flex 6300 two weeks ago and using the lastest SmartSDR software.  Noticed a slight amount of SSB audio distortion on 40 meters.  All other bands audio is near perfect.  Even at an output power of less than 10 watts the distortion is still there so I do not think it is RFI.  Using a Heil Pro hand held microphone with adaptor cable.  Using a Yeasu Ft-2000d  as a monitor of the audio.
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Jerry Wilk

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Posted 3 years ago

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EA4GLI - 8P9EH - Salvador

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Make sure you have the correct setting of BIAS and MIC PreAmp.
It is in the SmartSDR Radio Setup



This is the way it works on my 6300 with both Yamaha CM500 and Heil BM-10.



And these are my TX EQ settings and Mic slider. PROC off normally, only ON when trying to break a pileup.



And TX Low Cut and High Cut

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Jim Gilliam

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Seems like settings would not be the problem if the audio is great on all the other bands. Have you tried it into a dummy load full power?
(Edited)
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EA4GLI - 8P9EH - Salvador

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All settings can change from band to band if you don't have a profile or haven't save it properly. I would still make sure all the settings are correct and then move on to RFI. It just takes a minute to check.

Otherwise, open a Trouble Ticket with FRS, it is the fastest way to get issues resolved.
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Jerry Wilk

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Settings the same on all bands.  Most likely will open a trouble ticket latter in the afternoon when I get home from work.
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John n0snx

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My bet is RFI leaking from the coax somewhere in the shack...  I have experienced it too many times....99 times out of a 100 its RFI... everyone so so quick to blame it on the radio....You can have RFI from 10 watts just as well as 100 watts...very first thing I would do is swap our the jumpers one at a time...That weird little RFI bug can pop up and can sneak into even the best station... Here one day gone the next or vice verse not here yesterday and here today....You can even have no RFI on one antenna and simply switch antennas and you have RFI...sometimes its hard to find exactly where it is generating from.... Just my 2 cents worth
(Edited)
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Jerry Wilk

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First I will install the latest update and check my coax jumpers and see if it corrects the problem.  I had rfi with my flex 5000a but that time it was on 15 meters only that totally wipe out usable audio.  Took a load of ferrites on the mic cable and fire wire cable to correct.
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Jim Gilliam

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Out of curiosity, what kind of antenna are you using? If you are using coax on a balanced antenna are you using a BALUN aka ferrite beads at the feed point of the antenna?


Jim, K6QE

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Jerry Wilk

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Butternut HF2V ground mounted vertical.
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Gerald - K5SDR, Official Rep

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You need a common mode choke AT the antenna. This is true no matter what radio you use in the shack for unbalanced feed lines.
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Jim Gilliam

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vertical antennas can be "rf generators"  in the shack, also. Most people using verticals do not have a sufficient radial system to decouple the RF at the base of the antenna, and the braid of the feedline becomes one of the radials. It always a good practice to "choke' off the shield of a vertical at the antenna to prevent it from becoming part of the radial system.


Jim, K6QE

(Edited)
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KY6LA - Howard, Elmer

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Butternut HF2V - tested it for a diversity RX/TX antenna at the NX6T contest station

It was a total RFI special.. frankly it's amazing you only have RFI on 40M as it totally whipped out everything for us... lots and lots and lots of ferrites mostly cleaned it up...probably needed better radials but heck we only used it for one contest...

You can never add too many ferrites...
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Jerry Wilk

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Using 30 plus buried ground radials of variable length.  Downloaded 1.4 last night with no problems very smooth installation hats off to FRS.  Audio on 40 meters is being reported as good to excellent. Will add chokes at the antenna feed line connection as insurance.
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Jim Gilliam

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Talk about easy...I am on a cruise ship and couldn't wait any longer after reading all the rave reviews. I brought up my home computer with Teamviewer, remotely turned on the Flex and did the 1.4 upgrade 2000 miles away from Pasadena, Ca. After that I am listening to 1.4 on the cruise ship with Team Viewer. The audio is fantastic. Thank you guys at Flex!
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Lee, Elmer

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Buy one of these from this list and use it at the antenna   http://www.balundesigns.com/1-1-baluns/  I use 1115d

73  W9OY