Rig: Flex 6400
OS: Windows 10 Pro - 64-bit (fully updated to current release/updates)
I've been having this problem intermittently for a while. When I start an FT8 transmission, everything looks great (see spectrum on left). Then, quasi-randomly, the system glitches and the output goes nuts (image at right; same vertical scale as on left). Lots of wide-bandwidth spurious stuff appears, clearly visible in both the waterfall and spectrum display.
Previously, I had been able to circumvent this by shutting the system down and doing a cold boot (removing connection to power). Now, it no longer seems to fix things.
First thing I explore was changing the DAX "TX Gain". (It occurs irrespective of whether I'm at a very low modulation level, or up at standard levels... which for me is a setting of about "40" and TX level stays between -10dB and 0dB.
Other things I've tried (all unsuccessfully):
1. Shutting down, removing power. Restarting.
2. Completely reloading both SSDR and WSJT-X. (What a pain. No gain...)
3. Tried both previous release SSDR v3.0.27 and current v3.1.8
N.B. SWR is always << 1.2 : 1
System can go for days FB, with absolutely no problem. Then, spontaneously, it decides to act up in this bizarre way.
Could this be a hardware problem?
Thanks for any and all suggestions...