6400 has low transmit power

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  • Updated 2 months ago
Hi! My 6400 has very low RF output (under 1 watt in Tx mode), even with TX controls at full power. I just updated to SmartSDR 3.0.27. This is happening when operating with the latest version of WSJT-X,  v2.1.0.

I went through the process of doing a hard reset of my 6400, and no change.

Attached a a few screen shots of my setup. I am obviously overlooking something.

Any assistance would be greatly appreciated.

Bob - N7RJN



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Robert Nobis

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Posted 2 months ago

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Michael Walker, Employee

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Hi Robert

In you DAX screen shot, is that while in Transmit at there is no audio in the TX stream.  You also don't seem to decoding anything.  

You didn't show your WSJTx Audio Settings panel.  Can you show a screen shot of that?

Mike
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Robert Nobis

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Hi Mike,  

No the DAX screen shot was not during transmit. Attached is a screen shot of the WSJT-X Audio Panel.

Bob
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Robert Nobis

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Decoding occurs, however it is sporadic. It doesn't happen on every cycle.
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N8AUM

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I get no decodes sometimes and after restarting both WSJT & Smartsdr it starts working again. Something to do with DAX I think ? Does this with my Win7 & Win10 PC's
Good luck !  Vidas
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Geoff - AB6BT

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Also, the DAX button is not selected. It's gray not blue.
(Edited)
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Robert Nobis

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Yes, it is gray. Not sure how to select it to make it blue?
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Bert Sharp

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maybe im missing something...but the dax is not blue on the mic control on the screen shot right hand side of  pan under acc+

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Robert Nobis

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No you did not miss that. It was grayed out. I have now selected DAX on MIC control. 
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Robert Nobis

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Thank you. After selecting DAX in MIC Control I can now transmit. Thank you.

Here is a screen shot during transmission.

Now I need to resolve the issue of not decoding on every cycle. Thought maybe it was my clock being off, but it is accurate to about 20 milliseconds.

73, Bob
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Craig - KØCF

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The screen shot "App Volume and Device Preferences" is a Windows system setting. You must NOT have any DAX devices selected as Windows system devices. This will normally produce an error message. Choose speakers and a system mic for these settings, but never any Flex devices.
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Robert Nobis

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Hi Craig,

Thank you. I made this change to the Windows sound settings, but it does not seem to make any difference in operation. 

73, Bob
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Michael Walker, Employee

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The 200ms timing difference is fine.

I talked to Joe Taylor about how critical Time is and you can be +/- 2.5 seconds.  So, it isn't critical.

Mike
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Robert Nobis

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Mike,

+/- 2.5 seconds seems like quite a bit of tolerance, especially for FT8 with it's 15 second cycle. But, yes I have decoded transmissions that were over 2 seconds off.

Thank you and 73,

Bob - N7RJN
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Michael Walker, Employee

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I checked with the guy who wrote the code to be sure.  :)

This means you can easily hand sync a PC by watching other signals, or listening to WWV.

Mike 
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Ken - NM9P

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After you get everything set up, I would suggest saving a separate Mic Profile as “WSJT” or “DigU” and then associate it with the DigU mode ... that way you won’t need to remember to change parameters whenever you change from USB to DigU and back.

For DigU, I would also set the TX bandwidth from 0-3000Hz, in order to utilize the full audio bandwidth of the digital sub-band.

Ken - NM9P
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David Warnberg

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I also see TUNE, MOX as well as ATU and MEM all greyed out in the TX panel.. that indicates to me like the radio thinks it's outside it's allowed transmitting frequency range...

What does your Region show under "Settings" and then "Radio Setup"



Another thought... did you upgrade the Radio recently?  if so did you do a factory reset after that upgrade.


I'm also noticing you have an issue with the PC audio.. can you supply a screen shot of Device manager / Audio inputs and outputs?
(Edited)
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Robert Nobis

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Hi David,

My region shows "USA".

Yes, I did upgrade to SmartSDR 3.0.27. And yes, I did a complete factory reset after this.

I am not at my rig now, but will provide a screen shot of Device Manager a bit later.

Thanks and 73,


Bob - N7RJN


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Ken - NM9P

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On your WSJT-x receive screen, your receive level seems a bit high. I usually run the DAX RX level slider lower than 100 and keep the quiet band WSJT level between 20-30 to give it some headroom. If the WSJT RX level is much over 80, and especially if it exceeds the top, I get decoding dropouts.

My own settings on WSJT modes runs the Flex AGC-T OFF, with the Dax RX level slider at 50, then I use the manual AGC setting to set the WSJT meter at about 20 when the channel is clear, and bump it down just a little if a really strong signal drives it over 80. Then I leave it alone. It requires my local speaker volume to be reduced, but I seem to get really good RX dynamic range this way on digi modes.

It is a little more work this way.....YMMV.

Ken - NM9P
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Robert Nobis

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Hi Ken,

I will look at the DAX RX Level a bit later and let you know, as I am not in my shack right now. This might explain my decoding drop outs.

I will also check out your suggestions on manual adjustment of the AGC.

I did do one additional thing before I went to bed last night. I am operating Windows 10 on a Mac under VMware Fusion. I assigned some additional resources to VMware. Since there was very little band activity after midnight, I couldn't verify if this improved decoding. I will watch this today.

Thanks and 73, 

Bob - N7RJN
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Robert Nobis

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It appears I am not the only one seeing issues with decoding of FT8 signals occasionally stopping. There is a thread on the WSJTX@groups.io page titled: "Another case of decoding stopping..."  It would appear the problem may possibly be because of a recent Windows10 upgrade that resulted in some issues with the drivers used by DAX.  I will be following the groups.io thread to see how this shakes out.

73,

Bob - N7RJN