Transmit Waveform

Bob G W1GLV

I noticed a different waveform when th PA temperature is below 67deg Celsius and when it's above that temperature. Have I got a problem or is this normal?
Temp below 67deg Celsius


Temp above 67deg Celsius

John W9KXQ

Bob, I have seen the same results here.  My 6500 just came back from Flex as it was losing power.  Even at 10 watts in tune position into a dummy load, it was up and down from as little as 3 watts to 11 or so watts, set as 10 watts on the Maestro, even before it reached 67 deg Celsius.  Just FYI.  I was not running the Flex in excess of 40 watts, but still got the same waveform you show here.  I had to reboot the Flex to clear it up.  I thought it was related to the power dropping off issue.

WK2Y

Is this on all bands or just 20?

John W9KXQ

Bob, It has been about 4 weeks ago when I sent the 6500 in, so I am not positive, but I believe that it occurred on both 40 & 20.  Often after the Flex had been left on all night, and my first FT8 contact attempt in the AM would produce this waveform.  After rebooting, it was good for several hours.

WX7Y

try shutting down DAX and restarting just the DAX module, I leave my 6700 on ALL the time as a server and only see this after a few days / hours and restart DAX to clear the issue.

not sure this is the same on your radio or not but it is on mine.

your mileage WILL vary

73
Bret 
WX7Y

 

Bob G W1GLV

Thanks John, but I'm hoping that FRS chimes in.

Bob G W1GLV

Thanks Bret, my radio is on 24/7 also. Never related that to DAX but will try that.

Bob G W1GLV

I've seen it on 40 and 80 meters when the PA gets hot.

Bob G W1GLV

Thanks to everyone who offered some feedback.

Tim - W4TME

That waveform characteristic is definitely indicative of the DAX buffer corruption issue and shutting down the DAX applet and restarting it should correct the issue.

Bob G W1GLV

I shutdown DAX and restarted it, same issue. If I run the PA with some pauses in between my transmissions, I never see that. As long the PA temp stays below 67deg C it's good.

John W9KXQ

Tim, what is the long term fix for this issue? My 6500 just came back from your hospital a week ago and I had this issue again this AM! Thanks for your help.

Tim - W4TME

The workaround until we can address the DAX issue is to restart it periodically.  There will be an upcoming feature in SmartSDR v2.2 that will start DAX when you start SmartSDR rather than have it start when the PC boots and remain running until you either (a) shut it down manually or (b) reboot the PC.  This should help some since the corruption issue is resolved by restarting DAX, so with this feature, it might not run as long and the frequency of the corruption is decreased.  This is not the fix, but it should help for some.