Being having a problem over the last few days when transmitting FT-8: the power has been modulated by what I do not know..ALC level bouncing and power fluctuating between about 75% and full power. Time to find out what was happening.
It looked at first like audio modulation so first thing to check was the audio setup and drivers in device manager in Windows 10. I removed all audio drivers using IOBit Driver Booster. Then, disabled the laptop sound card hardware as this laptop doesn’t need sound. Reinstalled the SCU-17 soundcard drivers and then connected up my USB hub that connects both the SCU-17 and the RigBlaster Advantage as just having 1 lead going to the laptop makes it easier. That USB lead has a 31 type ferrite choke just to block nasty RF!
Plug it in and off we go. Still modulating the power…bugger!
Why is it doing it now, why has it just started? Then I remember: I reseated the SCU-17 and fitted a new USB lead and there’s the culprit: A really high quality Lindy 30cm USB cable. Replaced it with a cheap 1m China cable with a ferrite on and clean signal returns…not perfect but those needles arfe no longer bouncing. Happy boy