On FT8 transmit audio cracks/pops Flex-6600

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  • Updated 1 year ago
When running FT8 transmits pops/crack noise when. My radio is a Flex-6600 running SmartSDR 2.4.9, WSJT-X, 100watts. Power Supply is 50 amp Astron (non-switching) Some times 2 or 3 in a 15 second transmission. It is not predictable just when. It seems to be affecting the decoding by the person I am QSOing with. He misses decodes when I am -10 db for example.My computer is a Dell 3668 I7-7700 and SSD drive, plenty of CPU and DRAM. Cat 5 eithernet cables from comcast modem/router.

I am attaching a screen shot I just made and you can see the horizontal spikes on the waterfall as well as hearing it in the MONITOR headphone. I am using the tune button on wsjt-x. It is much more pronounced when in a QSO probably because of wider bandwidth. Also used Flex Tune button. first picture,

Looking for ideas or things to check to further define problem. 2 pictures attached. Look at the black waterfall segment. The first screenshot is into a dummy load with 100 watts and 0 watts. Keyed with Tune button. Not a bright on 0 watts but there as you can see in first pic. Second screen shot I took first into antenna, 100 watts wsjt-x keyed. This is not new just seeing more missed calls as operating much more FT8. When operating it is not as consistent or repetative as as shown in the pictures.I just add a third screen shot that is a better picture just above 73s.
Bill W9JJB
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Posted 2 years ago

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I have run some more testing and found something interesting. If I have a panadapter on 20m and one on 15m and one receiver on each band. I get a click on the 20m transmitted signal when I change the 15m receiver slice from say CW to SSB. It is very repeatable and happens every time. I did this by tuning my Yaesu radio FT1000MP to listen to the Flex 6600 transmitted signal. I am using a dummy load. Neither wsjt-x or slicemaster is running for this test. The click signal is about 700 hz below the carrier on only the low side. I also get some click once in a while 10-80 seconds but more centered on the carrier. I see these clicks on the panadapter and in the Yaesu receiver audio.

Bill W9JJB
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Gary Wells

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I am having the same snap sound every few seconds as well from my 6700 under the same scenario as Bill while in the receive mode. It is unnerving when a loud pop randomly comes from the speakers. I'll do more testing following Bill's approach.

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I had a similar problem with my Flex 6300 on ft8.  I was able to reduce the scope of the problem to using the tune button into a dummy load on low power.  I powered down the 6300, turned off the power supply, waited 10 sec., turned on the power supply, turned on the 6300.  The problem was gone and has not reappeared.

Speculation:  There may be a software synchronization problem among the various radio control processes that is resolved by a hard reset. 

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Ben Laws

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I had a similar issue which was solved by upgrading the DAX to 2.4.9. It was easy to do, there are instructions at flex. Ben : W6PXE.
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Sergey, R5AU

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I have no issues such described above with my 6700 and ver 2.4.9 btw usually I have at least 2 PAN , one with Digi(FT8) and second / third with CW( SSB not my favorite mode)

No interrupts, No cracks, I am running under virtual machine with Parallels ( 4 virtual CPU core split) on my Mac in parallel with CWskimmer+ Log+slice master +DDutil and on Mac as well some apps running simultaneously

CPU utilization :

in Win =~ 30%

Total =~ 40%
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Richard Zalewski

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New user of my 6600M and have the same noise.