Tx wide band noise

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  • Updated 6 months ago
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Hi  i always have that issue since i have my first 6500 and now on my 6700

radio here run 24/24 ,from time to time radio start to xmit very dirty signal 
and even only plain white noise  ,only way to recover it it cold reboot of radio

until now it not a major issue since radio was semi remote ,so i have SmartSDR on my computer screen and see signal on panadapter  ( on 2M no panadapter on xmit) , but now  it fully remote trough a VPN 
for reduce my internet consumption  most of the time i only have DAX and WSJT-X running 
so when radio start to transmit  wide band noise @ at legal Limit it become a big issue 
and seem that V2  not solve that , happen 2 time in last 24 hour 

i personally think it a really major issue that must been solve since long time 
and have way to shut down TX when append  !

noise Generated i variable , last day on FT8 signal look almost normal FT8 but whit some very high phase noise over it .  someday only transmit very wide band noise .
this morning on MSK144 it alternate from normal signal to wide band noise 




Best regard   Marc  VE2PN / VE2OLM
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Marc Lalonde

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Posted 9 months ago

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Tim - W4TME, Customer Experience Manager

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As indicated, you are operating a digital mode (DAX enabled).  There is a known issue with DAX that can result in periodic TX and RX audio corruption (distortion).  The current workaround is to stop and restart the DAX client.  This is an issue in our bug tracker (#2391, #2632) that we plan to address.
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Geert Balsma PA3CPS

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Hi Tim,

Sometimes my FT8 signals looks like on the picture. When i restart my computer it works perfect. It this the same DAX problem?

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Tim - W4TME, Customer Experience Manager

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Yes, that is the expected behavior of the DAX audio corruption issue we have in our bug tracker.
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Marc Lalonde

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Hi Tim   ,that also have sometime happen in SSB  ,whit SmartSDR running on my local PC whit USB mike.   have expeced that DAX packet have CRC and if something wrong it Stop TX     
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Tim - W4TME, Customer Experience Manager

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Marc,

Please put these comments in your open HelpDesk ticket if you have not already done so.  And ask Dudley to assign your HelpDesk ticket to me
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Al K0VM, Elmer

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Tim,
  All of the DAX TX issues that I have seen have been band limited by the TX filter.. Don't see that in Marc's case.
AL, K0VM
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Bill W2PKY

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Al- I would agree does not look like something from DAX. The Low & high cut parameters are set correctly thus limiting any input signal.
The fact that Marc had this issue with 2 different radios would suggest something common to both. Could it be power supply induced or RF Feedback?
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Al K0VM, Elmer

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Arcing RF connection??  Coax/connector/antenna ??
AL, K0VM
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Marc Lalonde

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Hi  must said that the very wide band noise  is the exception most of the time it more like very noisy signal that fit audio pass band 

power supply is astron RS-35

RF Feedback is not probable ,station is inside a maritime container  ,power and internet is underground in metallic conduit  and all RF is troug lighting arrestor 
have worked really hard  for station generated noise not got pick-up by antenna

i assume that HF antenna  on ANT1 and located 20 feet away from 6M beam 
not pose issue since normally radio relay have good isolation (never try the FDX )

since reboot of radio fix the issue ,not think it Arcing or bad connector 
(Edited)
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Luis del MOlino

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It has happened to me several times too working with the WSPR mode.. Sometimes I have discovered that the TX Spectrum was enlarged and I was transmitting noise instead of a WSPR signal, after several hours of continuos correct operation.

Tim has already said it is a well know issue, but still not resolved. When?

Luis EA3OG
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Marc Lalonde

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i agree that a major issue  ,that may not meet the FCC
have ruining flex since 2014 and as far i remember always got that bog
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Bill NE1B

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The main issue is between DAX and your PC/Laptop running 7x24.   It is solved by closing DAX and re-starting it again every 2 or 3 days.  I had the same issue when running FT8 from my laptop.  No issue with my Maestro remotely since I shut it off each night.   It also varies based on the computer model running digital modes.
73,
Bill, NE1B
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Marc Lalonde

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Hi  Tim  i have now big doubt that my wide band noise  it only a PC side DAX issue  

The issue hit again  ,but take time to do more test   ,it intermittent on the same  JT65B TX sequence it go normal the wide band noise then go back to normal  and so on  (sometime white noise  ,sometime kind on multi-tone)   noise seem to spread  +/- 15K from carrier

1-) i reduce power to very close to 0  and no change      
2-) move from local PC to remote site PC trough Teamviewer  ,no  change

but i have notice that i may temperature related  this night it drop to 9 degrees Celsius
and have to stop since not able to have a single Sequence whiteout go into noise at some time 
then  later  have do more test and looking good but temp have raise to 16 degrees

usually electronic no have any problem whit outdoor cold climate as electronic assembler
i have thousand of Board build that work outdoor whit no failure as long it not have thermal cycling 
that reason i let radio  on 24/24  and i use external amplifier 

so will make more night operation during this week-end EME contest so got back whit more detail
but already pi...  me off  to miss VK station because of radio issue  ,hope it work better for the contest
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Marc Lalonde

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HI  ok once again operation not possible 

(Edited)
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Marc Lalonde

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whit sound  and ~ 1W    Restart of DAX no change  
need to reboot radio then good for some time  ,really no fun on a week end of constest 

(Edited)
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Tim - W4TME, Customer Experience Manager

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What version of SmartSDR are you running?
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Marc Lalonde

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 2.0.19   , i remove the cold temp from suspect ,during week-end temp dropped to 5 Celsius
and reboot radio before moon pass ,permit to avoid issue during constest
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Tim - W4TME, Customer Experience Manager

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Thank you
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Marc Lalonde

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need to reboot today  ,after 4 day of inactivity
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Marc Lalonde

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Hi  Tim  new info this morning   ,still have noise but from "TUNE" and on 10m band
as usual reboot fix the issue 

so different cable , AMP antenna etc etc ...  
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Tim - W4TME, Customer Experience Manager

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Marc, Please submit a HelpDesk ticket for this issue.  I think it is time to perform some more detailed diagnostics on your issue.  We may be dealing with a possible hardware issue.
(Edited)
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Marc Lalonde

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HI  ok but soon the remote site will become no longer accessible for the winter
so hope not need to send back radio ..
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Tim - W4TME, Customer Experience Manager

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I hope not either, but that could be a possibility.
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Tim - W4TME, Customer Experience Manager

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Official Response
Issue determined to be a probable hardware problem.
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Marc Lalonde

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HI Tim please check whit Dudley  ,have re-open the ticket issue still not solve
and not to mention that i start to be really ......   ,for now i have a 10,000
$ CND door stopper
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Marc Lalonde

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make lot of test today waiting feed back from flex and i may confirm now it temperature related 
once cold to 0 deg Celsius radio stop transmitting ,then when heat from 0 to 10 Deg it TX wide band noise ,10 deg and up  ,  back doing normal operation 

next step is buy a can of "freeze"  and try to find the bad part  , all IC i check was -40 ~ +85

hope only my radio  have this defect ,since Bouvet island is quite cold to ;-)



that was tune into XVRT port into dummy load  from -5 deg to almost room temp


 
a bit of wife hair dryer and back to normal 


 

next thermal cycle from +4 to room temperature in ~10 minute
once again start by no TX at all -->  then noise  --> intermittent noise  -- > normal 

i let it in tune on XVRT port for 2 hour whit not a single glitch @ room temperature
(Edited)
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Marc Lalonde

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i do more testing

i exclude TXdac and buffer from suspect list, and now focus on the FPGA itself
almost sure it nor a bad solder  ,if shot small amount of cold spray close to FPGA TX go crazy



since the FPGA  cost ~1500$  CND  and seem no stock anywhere my own investigation end here
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ka7gzr

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I would be careful in drawing any conclusions from freeze spray applications. Hammering an individual component with freeze spray is interesting but not conclusive. To do it correctly you must  put the entire transceiver in a temperature controlled environment allowing all parts to experience the same environment to draw any conclusions. 

Jim

ka7gzr 

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Marc Lalonde

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Hi  Jim   , i found the issue and temperature correlation wen i operate at night wen outdoor temperature  drop ( radio is on unheated maritime container on mountain top ) 

once radio back to my home i  validate my theory operating radio inside my freezer  (+4deg)

then send it to flex for repair , Flex tech do some work but was not able to duplicate issue so return me the radio.     take 45 min of drive to reach my remote site so when i install it it already cold
and fin is still not work .....

so before ship it again i put it on my bench and try to isolated witch part if faulty and how to quickly test it on the bench for help Flex tech to fix it  , that were the can of  cold frezze   appearing  on the story   ,once on my bench i also validate if have bad solder or other thing

so here in north is easy i only to put radio outdoor for 15 minute   and use hair dryer and find issue in 5 minute   ,but  Flex in Austin Texas , it bit more hotter ;-)   

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