Distorted SSB TX audio - Did you fix it?

[VK5IR]

Hi

For anyone who has actually *tried* it, can you confirm whether re-flashing the bootloader actually fixed the distorted SSB audio fault?

Thanks.

[la1tpa]

I have reflashed the bootloader twice, but still get terrible modulation reports.

73! Mads, la1tpa

[VK5IR]

I have reflashed the bootloader twice, but still get terrible modulation reports.

73! Mads, la1tpa

That's rather unfortunate.

Thanks
VK5IR

[gatorjj]

I had some issues with SSB in the field, but never at home. It turned out to be RFI, which a choke on the feedline seems to have solved.

J.J. KF4VE

[la1tpa]

I had some issues with SSB in the field, but never at home. It turned out to be RFI, which a choke on the feedline seems to have solved.

J.J. KF4VE

That could also be the problem in my case. I have only used the rig in portable situations with a short feedline. Will test with an rf choke next time and report back.

73! Mads, la1tpa

[gatorjj]

It took a very long time to figure it out as it seemed intermittent until I decided to really focus on finding the problem. i.e. sometimes it seemed fine, sometimes I'd have issues in the field and come home to troubleshoot the radio and find no problems. Turns out 40m was fine, 20m and higher were being affected.

I had a choke I could insert at either end of the feedline, but it didn't seem to help much with the EFHW. After doing some reading online I played around with the choke at different distances from the UNUN and putting it at 4 feet away seems to have solved not only the SSB issue but even the weird noises I was having on receive (after transmitting). I probably need to get out a few more times before I'm 100% confident all is good now but I've done 3 POTA activations since and it was a completely different experience.

And luckily for me some guy was recording his activation on YouTube last time I was out, so you can hear that it sounds fine on 20m now https://youtu.be/-tfMvHd2Fhw?feature=shared&t=1453

J.J. KF4VE

[Tony F]

I re flashed the BOOTLOADER and the FIRMWARE three times and the distorted tx'ed audio remains. Truly a let down.

[dg8ek]

Hi all,

I'm having the same issue. I reflashed the firmware several times and I tested an external mic. Sounds similar to the internal mic. So I assume that the internal mic isn't damaged.
Any suggestions how to fix it?

73
dg8ek

[dg8ek]

A few more tests.
I've added a 1:1 trafo to the external mic connector and injected a signal from the PC. I did this to check if the quality of the audio depends on the level.
What i saw is that the level is not realy important. It works in a realy wide area in the same way.
I also removed the RF-board and add a small wire to the Drive-pin. A transceiver close to the usdx was used as a monitor. Same result.
Conclusion: The distorted audio depends wether on the audio level neither th RF-board.
Any ideas

73
dg8ek

[DL2MAN]

Conclusion: The distorted audio depends wether on the audio level neither th RF-board.
Any ideas

73
dg8ek

I did not come to the same conclusion, when I did my tests.
Distorted Audio was extremely dependent of input level.
Once you exeed a certain level you can see all kinds of bad behavior from mirroring etc.
Fun to watch also audio frequency dependency in the output spectrum.
You can almost paint pictures in a waterfall with that.

[Tony F]

I flashed in the Bootloader and re installed the firmware, Still has BROADBANDED audio. I re-flashed again the Bootloader and Firmware….still BROADBANDED audio. DL2MAN's uTube video stating to re install the Bootloader and firmware to correct the distorted (broadbanded) TX'ed audio does not work for my (tr)uSDX. The display board production date is Rev 1.2 - April 2023. The RF board production date is Rev 1.0 – Nov 2021.

Looks like this is an ongoing issue with many others.
Any other suggestions to narrow the TX audio from ~ 8 kHz to ~2.4 kHz or so?

[pe1nnz]

Things that might help:
- Reset with factory settings might help (hold encoder button on power up),
- not overdriving the audio input (999 not visible in display when mostly modulating.
- reduce drive setting
- use a narrow filter setting

But the real question here is what you mean with "BROADBANDED".. Bandwidth is generally measured within -3dB points.. so what do you see?

if you see with the -3dB points signal with 8kHz bandwidth then something is seriously off. If it's something like the 3dB bandwidth is 2.4kHz but i see artifacts of -50dB or more within 8kHz then yes this is normal behavior and this is not considered as broadband tx as the side-products are well suppressed.

[DL2MAN]

Just an addition:
When we were in Belgium, there was an OM who told us, that our modulation would sound distorted. He explained in great detail with terms, that sounded familiar to me from youtube/facebook/forum-comments.... So we listened to ourselves via web-SDR, and agreed (Guido, David and myself), that´s just how (tr)uSDX sounds. If you´re not affected with splatter in spectrum, you´re experiencing (tr)uSDX´s Sound. Remember: It´s all digitally generated. In this Video @22:14 your hear Guido´s explaination of why (tr)uSDX sounds different: https://youtu.be/Ze4jYq4KLsc?t=1334 Latest Beta Firmware has an modulation indicator: If you see 999 while speaking, you´re overloading the audio and should move further away from mic and/or talk less loud.

So we need to set the expectations right before considering a fault.

73 Manuel; DL2MAN

[la1tpa]

I have reflashed the bootloader twice, but still get terrible modulation reports.

73! Mads, la1tpa

It seems like FW Beta 2.00v might have solved my problem. The new over modulation indicator certenly helps a lot.

73! Mads, la1tpa

[DL1DBY]

Just an addition:
When we were in Belgium, there was an OM who told us, that our modulation would sound distorted. He explained in great detail with terms, that sounded familiar to me from youtube/facebook/forum-comments.... So we listened to ourselves via web-SDR, and agreed (Guido, David and myself), that´s just how (tr)uSDX sounds. If you´re not affected with splatter in spectrum, you´re experiencing (tr)uSDX´s Sound. Remember: It´s all digitally generated. In this Video @22:14 your hear Guido´s explaination of why (tr)uSDX sounds different: https://youtu.be/Ze4jYq4KLsc?t=1334 Latest Beta Firmware has an modulation indicator: If you see 999 while speaking, you´re overloading the audio and should move further away from mic and/or talk less loud.

So we need to set the expectations right before considering a fault.

73 Manuel; DL2MAN

Once when using the (tr)uSDX in the field in SSB mode, a fellow ham living nearby who was listening to my signal via ground wave contacted me and advised my to stop transmitting because of "distorted audio". I then asked all contacts on that day on 40m and 20m how my signal sounded. They all told me the signal quality was "normal". With the noise from the transmission path added, the digital artefacts seem to disappear in the noise.

Of course, when I was home again, I checked whether I had an unusual wide signal, which wasn't the case.

vy 73 Dieter DL1DBY

[Kd4zly]

Hey guys. Ok so on my 2 days of trying to figure out the "distorted modulation" and testing with a friend 1300 miles away, one a mile away and my wife saying audio audio in the back yard lmao I came to the conclusion that if I lower the Tx drive to 2 for regular use, the audio cleans up to almost perfect and 3 and 4 for long distant contacts. But just like Manuel mentioned, the little radio have his own distinctive sound. My trusdx sounds best on 2. Also make sure you put the radio right on frequency. sometimes we think we are but we are not. Just my two cents Cheers! 73's

[SP9TKW]

If I could refresh this topic.

My truSDX was working OK for over a year. Recently during SOTA activation chasers started comment on my poor audio - very distorted, similar to RF in the signal. It was difficult to understand not just metallic processed audio.

After returning home I started to investigate.

First I made QSO on 40 using EFHW with CMC - comment a poor audio
Then I switched to Delta Loop with CMC - still poor audio
Reset radio - same result poor audio
Reloaded BootLoader and FW - poor audio
Reloaded BootLoader and FW 2.00x - poor audio even when meter shows values way below 999
reduced drive to 2 - I still have poor audio.

Any more steps trouble shooting I could try? Tests were completed with internal and external mike. Filter setting 2k4

I have classic RF board from Sunny. I have 3in1 oscilometer for possible further investigation.

Thanks for any suggestions and help.

73 Marek

[gatorjj]

Hi Marek, see my experience below. I haven't had any audio issues since then, RF is definitely tricky to solve and the (tr)usdx is probably pretty sensitive to it.

I'm curious did anything change with your setup coincident with the issue?

It took a very long time to figure it out as it seemed intermittent until I decided to really focus on finding the problem. i.e. sometimes it seemed fine, sometimes I'd have issues in the field and come home to troubleshoot the radio and find no problems. Turns out 40m was fine, 20m and higher were being affected.

I had a choke I could insert at either end of the feedline, but it didn't seem to help much with the EFHW. After doing some reading online I played around with the choke at different distances from the UNUN and putting it at 4 feet away seems to have solved not only the SSB issue but even the weird noises I was having on receive (after transmitting). I probably need to get out a few more times before I'm 100% confident all is good now but I've done 3 POTA activations since and it was a completely different experience.

And luckily for me some guy was recording his activation on YouTube last time I was out, so you can hear that it sounds fine on 20m now https://youtu.be/-tfMvHd2Fhw?feature=shared&t=1453

J.J. KF4VE

[SP9TKW]

Hi Jeffrey,

Thank you for responding and giving your sound sample. I do not have recording I am afraid, but one of the hams played it back to me and it sounded much much worse. I could not understand much so I am even amazed that this guy managed to get my call sign.

I have CMC which I use with my EFHW4010. It's 9 turns of RG174 on FT114-43. I place it just before TRX.

My issue developed after I blew finals. I had high SWR on antenna working SOTA (bad connection). I replaced FDT86256. I made couple activations and the report of bad audio started to come in.
My Bias is 160 and I tried 156 and 152 setting but it is still bad
As I mentioned earlier I reduced TX drive to 2 and still I get badly distorted audio comments.

I hope this sheds some more light on this issue.

73 Marek

[Rocky]

I love the radio, I really do, and I'm urgently brushing up on my CW, but desperately hoping for further improvements to the TX SSB so as to avoid, as Dieter, DL1DBY, has also experienced, being "advised" by other local hams to... stop transmitting because of "distorted audio"!
I'm profoundly grateful to hear what doesn't work and sympathise with the torment Marek has endured on our behalf, in his research.
I just hope someone can come up with, and clearly describe, a terrific fix - ideally via a new firmware download or otherwise, for this perplexing issue.

[KE0QQQ]

Rocky,
This is my first reply on this site. Try this. Place the radio on your knee and talk normally. The mic is like a conference phone, it picks up everything and can be overwhelming

Talking with the radio at arms length,using a normal voice took care of my distortion. Once I did that others could not believe the quality of the SSB. 10 meters is iffy but from 15 to 80m, I have had good reports

I hope to get mine back on the air this summer after taking a year off with West Nile Virus, darn mosquito almost killed me while camping the last time I used mine. Watch out for it, nasty debilitating disease. Use Bug repellent

I also love the radio and done my share of building of three of them.

I also learned not to pull the boards apart once the radio is built and tuned. The connector between the boards is suspect to funny SWR and wattage reports if you are always pulling it apart, at least that was my experience.

Thank you for the chance to reply !

[Rocky]

Yes, have tried that now...could you please advise what settings for Noise Gate and TX Drive did you operate the radio at?

[SP9TKW]

Don't get me wrong, I love this radio too and done several SOTA activations with it. It was my prefered option both summer and winter, but this recent incident put stop to that I am currently using my original mcHF v0.6.3.

When all was well I had TX Drive at 4 and PA Bias at 160. Once I started to get distortion results, first I ensured that microphone is good 8-12inches from my face. Then I reduced TX Drive first to 3 and now to 2.

73 Marek

[Rocky]

"- Reset with factory settings might help (hold encoder button on power up)"

Would reset to factory settings require reinstallation of the boot loader in addition to reloading the firmware?

I don't want to give up on the hope of fixing the SSBTX audio as so many others seem to have joyful, problem free operation and it would be so great to be able to use the SSBTX capability if it could be made to sound intelligible!

Please, anyone with further ideas for fixing this, do continue to set out your suggestions for improving the SSBTX audio...a solution must eventually be forthcoming...

73, Rocky