6300 WSJT 10 / JT6m waveform on TX with 1.6.17

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  • Updated 3 years ago
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Hi folks
Recently migrated from Icom 756 Pro3 to be a new user of 6300 with 1.6.17 installed. Reasonably experienced JT6m user for meteor scatter, etc. using WSJT-10 on 6m mainly.
I'm having issues with the tx waveform as it appears on the waterfall, as it appears wide, and distorted (into my dummy load). Can anyone signpost me to an "exemplar" image of what a properly setup and working JT6m TX waveform should look like? I've Googled but no joy.
Just to be clear: I can use JT9 / JT65 etc. perfectly well using WSJT-X...but  JT6m mode (which remains dominant in Europe) is only available within WSJT-10..a totally different software. 
Have exhausted options with support ticket which concluded my Q6600 based system is probably underpowered..but I still want to see what I need to be aiming at. 
tnx, Ian GM4KLN 
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Ian GM4KLN

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Posted 3 years ago

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Ken - NM9P, Elmer

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The obvious answers first...

1) Make sure that your TX audio remains at least 3 dB down from the red indicator on the Transmit Audio panel. if you get into the red, you will distort rather quickly.

2) The waveform displayed while transmitting are not always exactly what is actually going out of the rig, especially anything outside the TX Slice filter flag display.

3) If your monitored audio (Via the MON function) sounds raspy, you need to close DAX and reopen it. Sometimes it gets some sort of data/memory overflow after being active for a long period of time and can get flakey. A simple close and reopen of DAX usually sorts it out.
Good luck,
I Hope this helps.

Ken - NM9P
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Ian GM4KLN

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Thanks Ken
#1 noted and complied with: even when barely registering on the level, same effect. 
#2 interesting..the displayed waveform could be a red herring then. there is no-one local to me (Highlands of Scotland) that I know of that can monitor my actual signals so I may need to install some form of remote monitoring / recording facility. screenie below (I hope) the thing that worries me is the bandwidth......
#3 the displayed waveform is identical whether the station has been switched on for 1 minute or 1 day: stop / starting the DAX makes no difference either - it's not that it changes from good to bad - it always seems to be bad. I've seen the other post about a similar scenario, but mine is working perfectly with WSJT-X. 

73, Ian GM4KLN
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Ian GM4KLN

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thanks Tim
knocked it back to about -10db TX...2nd image below. if I reduce DAX TX drive much less than that, the RF PO just goes to single figure watts: it is incredibly sensitive to TX drive - almost ( but not quite) all or nothing. 
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Al K0VM, Elmer

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Ken,
  As far as I can tell, the spectrum your seeing is the result of the signal genrated by jt65m.. The baud rate of signalling in jt65m is significantly faster than say JT65A  and it seems like the transistions may not be optimized for minimum bandwidth.  If you try jt65A without changing anything else, you should see a much 'cleaner' display, primarily due to the low signalling rate..

AL, K0VM
(Edited)
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Mike Hoing

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Looks like your also driving 80 watts on a low power mode

Mike
N9DFD
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Rob Fissel

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Mike, JT modes are weak signal modes, not low power/qrp modes. Also, the few times I've done any meteor scatter attempts on 6m with JT modes, I drove it upwards of 300 watts (only have a 2el beam). 
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Ian GM4KLN

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@Al - indeed I do see just that having now experimented with JT65a - perhaps the profile is not a million miles from what it should be - fine tuning apart: patently some optimising needed. I know the two modes are optimised for radically different needs, but I totally take your point, thanks. 

@Mike - JT6m is not a low power mode - not sure what you mean? folk regularly run full legal limit during Meteor Scatter QSO...but regardless, would it make a difference to the waveform? 

73, Ian GM4KLN
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George Molnar, KF2T, Elmer

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Here's a similar shot from this end -- JT4 instead of JT6, but that shouldn't make a huge difference, I don't think.

Might want to tweak levels between WSJT-10 and DAX and SSDR, maybe there's a sweet spot you can reach?

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Rob Fissel

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George, side note - any idea why they pulled JTMSK out of WSJT-X 1.6? It was in the 1.6 developer version...
(Edited)
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Ian GM4KLN

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Thanks George - JTMSK is next on my experimentation list :-)    
A QSO would be good - you never know come the next season.....we can all dream I guess!
Look forward to when all these modes are in a single software release too...

Rob, I've reverted to v1.6.1 dev for now too....
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George Molnar, KF2T, Elmer

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Rob, not sure of all, but believe the idea was that 1.6.1 was not the alpha area for 1.6, although there surely was some crossover. 1.6.1 does seem to have morphed into 1.7 pretty solidly. Looking at things from here (NOT a dev team member) it looks good for a 1.7 release pretty soon.
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Bill W2PKY

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The new decoder in 1.7 is nothing short of phenomenal. Have seen 27 "Qs" more than once on 40M @ night. Noticed the decoder can log more than one station on the same exact frequency. Very exciting gains in performance. Looking forward to any improvement from here out.  JTMSK 6M meteor scatter exhibits similar performance.
Great job by the development team.
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Rob Fissel

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I've read some great things about the new decoder in 1.7. Excited to say the least...