DAX TX Gain question

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I'm occasionally getting responses that my signal is too wide, or spalattering when operating JT65
This am a fellow asked if I had the Compressor on.
Obviously not as the compressor is not enabled when in DIGL mode.

So I turned my attention to DAX.
I haven't adjusted anything there in a while.
Found the TX Gain was set to approx 1/2 scale, Where a online SSB qso respondent said I sounded good many months ago.
Haven't touched that setting since; as I do very little SSB.

So for now I have set the DAX TX gain to minimum.
Does anyone know if the DAX TX gain may have been my problem?
I'm a cw-rtty-digital guy, rarely can I even find my microphone.

So are there any JT guys among the group? What do you set your DAX TX Gain to???
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Bill-W9OL

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  • verklempt

Posted 4 years ago

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Bill-W9OL

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oh one more thing. No I did NOT have the amplifier online....Flex RF Power indicator at half scale.
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Ken - NM9P, Elmer

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Have you set the sampling rate to 48,000 for both ends of each DAX pipe and matched that frequency in your Digi programs? Or an evenly divisible frequency? I have read that If not, you can get some digital conversion errors that can add some small distortion to the signal.

I am also careful to observe the signal level meters in the DAX control panel and make sure that they don't go over maximum. But come digi programs like to have less drive than that.

As far as Mike level, I have always had a clean signal as long as I keep the Mike level meter out of the red.
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Bill-W9OL

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If by Mike Level, you mean the Flex Display 'Level'
It's green and only 1/2 way, In fact it ends right under the word "Level"

Question for your terms "how can a signal go OVER maximum"??? :-))
Just joking!

But as far as I can see, there is nowhere in wsjt-x that I can compare and\or set sampling rate
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Bill-W9OL

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No I wasn't...
First time as a young child, with blinding headaches
Last time an infection. Neither case do I remember any sedation. But I was too ill at the time to remember.
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DrTeeth

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That procedure is one of several things I would not have done without sedation. It's up there with prostate biopsy and intra-occular (in the eye) injections.

Glad you recovered.
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Gary Robertson - KY5R

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Ken - could the DAX buffer overrun problem also cause distortion to my K9DUR Voice Keyer transmissions? I have tried everything but I cannot eliminate the distortion when I use K9DUR's Voice Keyer.
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Ken - NM9P, Elmer

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I use K9DUR Voice Keyer, and this is possible.  I always "cycle" the RX/TX buttons in DAX Control Panel at the beginning of every session just for safety.  But I have found another source of distortion, too.

If I simply record a .WAV file using Audacity and try to run it directly via Voice Keyer and DAX into the FLEX, there is WAY too much bass and it overdrives the rig.  
I have found it necessary to use Audacity to equalize the recording to remove some bass and enhance the 1-3 Khz frequency bands, then compress the recordings to keep them all at constant level  (0 dBm).  Then I carefully adjust the DAX TX slider in DAX Control panel to make sure that I don't overdrive the 6500.  

When I take these precautions I have excellent results... no distortion, and audio that is very close to my live mike.  (If I have drawn the EQ Curve correctly.)

Ken - NM9P
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Gary Robertson - KY5R

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Thanks Ken. I will try your suggestions. I really want to make K9DUR's voice keyer work well for me.
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Al

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On many occasions I have seen distorted JT65 and JT9 signals. Where the main signal has additional ghost signals every 170 hertz (JT65) or every 17 hertz (JT9) both above and below the main signal. These ghost signals seem to caused by too much power and a drive signal with high harmonic content. This does not seem to be what you describe. However over the last 4 to 5 months I have been seeing some very wide JT65 signals (see the attatched screenshot at time 0149) which may be what you describe. They look like they are somehow harmonics of the signal shift frequency. Again both above and below the start frequency of the JT65 signal. I try to look at my drive signal when I transmit, trying to make sure the drive signal is clean with very low harmonics. I think my signals are clean but I hope if anyone sees my signal distorted in any way that they send me a report so I can fix the problem. If any one can explain the signal on the screenshot I
sure would like to know what the cause is, it seems to happening more and more. I run my DAX TX gain level at the point one step below the point that the drive level meter goes from yellow to red. 

 
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Al

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The screenshot is a little small here is the file.
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Martin Ewing AA6E

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Al - I've been noticing the same issues with JT65 using wsjt-x software via DAX from the 6700.  When I look at the 6700's high-res waterfall, I don't see the "splatter", so I suspect it's an issue with DAX. The acid test would be to connect the 6700 and wsjt-x using old-fashioned sound card technology to see if the problem goes away.  Changing DAX gain (in Windows on receive) does not seem to affect the problem.  I'm not aware that there are any adjustments in the Flex radio for DAX sending.  Is that right?

On transmit, I try to monitor my signal through another receiver on site.  It sounds clean to my ears, so it's probably OK.  (On the other hand, the apparent splatter on receive is down by quite a few dB, so I'm not sure how audible it would be.)
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Ernest - W4EG

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Over power is one cause of splatter as I witness last night on 160m by a station in AZ, I am in San Diego.
That station was 3 kHz wide and we are about 300 to 400 miles apart.    I noticed that operating with JT-65 v1.4, I have to watch my Level not to exceed 0 otherwise; I received nasty 13 letters complaint .
I hope this is corrected by K1JT for the Flex user;since previous versions DID NOT cause any problems.His SmartSDR does not work and it has to be replaced by using the Kenwood TS2000 radio in it's place.
(Edited)
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Bill-W9OL

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I've moved my DAX TX Gain to the very minimum and still seem to have some output indication
So far no complaints from anyone.
I'm missing a lot of contacts, which I assume is due to limiting myself to as weak a signal as possible.
I presently have the DAX TX Gain at the minimum as well as RF Power in SSDR.
I'm also following the suggestion to close and reopen DAX
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DrTeeth

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What is the output level indicator reading. You should set your DAX TX high enough so that the peak reading (the solid rectangle) stays yellow. My DAX TX is at 41 to do this with WSJT-X Pwr slider at maximum*. You mentioned that you are using DIGL in your OP, AIUI isn't DIGU supposed to be used?

*I never use this as not only does it reduce power output, but it also reduces the signal drive too.

Hope this helps.
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George Molnar, KF2T, Elmer

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Hi Bill,

Here are a few screen shots from my end. DAX TX level is 41, RX is 20. Everything seems to work smoothly. Using WSJT-X 1.4 (beta). I set the AGC "off" and adjust the slider to about 30 db on the WSJT RX level meter (WSJT-X slider halfway up). RF output is adjusted with the RF Power slider in SSDR. For 6m and 160m, I have a "Digital QRO" transmit profile, for the other bands, it's just a "Digital" profile with less power. Both seem fine.

Sometimes with WSJT-X 1.4, I see more of a "bloom" in the waterfall that isn't apparent in SSDR; AGC settings can affect this, but I think the new version of WSJT-X is more sensitive overall, at least in the waterfall.

Picking up on an earlier comment - Windows sound level controls don't affect DAX, as far as I recall. I just leave them centered "because."

Heard you this morning and you sounded/looked fine here.

See you on the bands!


Geo

(Edited)
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Ernest - W4EG

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George,
The level control if it goes to the right of 0 Level, locals ask me to reduced it.
I do the reductions with the TX Gain and bring it down to the left of the 0 Level where your indicator shows by one or two hash mark.  The locals are happy and I don't receive any 13 letter correspondence. :)
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Al

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The DAX setting on my 6700 are RX 20 and TX 41. The wide JT65 signals I mentioned in my post are not all the way across the 4 kHz display some of the signals are clean and right next to the splattered signals, however when I see the problem there will be 2 or 3 signals next to each other. I am using usb mode with the 4 kHz filter so I can jump back and forth between JT65 and JT9 without any changes at all. Works fine for me. I also am still using Version 1.3,r3673 of WSJT-X.
Al   N4AB