Jon,
A couple thoughts.
The USB section of the SoftRock RXII is supposed to be electrically (DC ground and +V buses) isolated from the rest of the circuitry. There are optocouplers and a transformer to accomplish this. The “ground” of the USB section should have very high DC resistance to the “Ground” of the main board. If that isolation is compromised somehow then noise on the USB lines will get coupled into the AF/RF circuits.
There are add-on USB filters sold to clean up USB noise. I have never used one but know they are sometimes helpful depending on the situation.
See e.g.
Roger
toggle quoted message
Show quoted text
On Jun 7, 2021, at 2:40 PM, JonI via groups.io <ji425bt@...> wrote:
Hi Mike,
Well, when I unplug both the monitor and keyboard, the most of the offending "birdies" go away. I had just hoped to be able to keep the keyboard plugged in. Others are suggesting a wireless and I may go with that. Just as an experiment, I lined the non-key inside of the keyboard today with sticky aluminum foil, then stuck foil around the USB cable leading from the keyboard to the USB connector on the desktop. Did not make much difference.
I guess I can just turn off the monitor as I'm using RDP anyway and controlling everything from the laptop. Of course, would still like to solve it. I started using ferrite chokes on the monitor cable with success, but ran out of chokes.
There are a couple of other sounds I get from about 3- 5 Mhz. Not at the spike so I think it's RF, but not sure if it's coming from me. I will try and video and post those. I was able to null the loudest one out by turning the loop.
Jon
On 6/7/21 5:06 PM, vbifyz wrote:
Jon,
Interference to Softrock comes in 2 different flavors.
1. Interference coming through the audio connection ("ground loop") shows up as a symmetrical center hump, or some other symmetrical picture on the waterfall. USB devices typically show up as spikes at + and -1kHz for keyboards, and +-8kHz for higher speed devices. These humps/spikes don't move when tuning the VFO.
2. Interference coming through the RF input is typically periodic spikes, often widened, on the waterfall. Not symmetrical, but repeated every 11..18kHz (solar panel inverters, variable speed votors), 62..64kHz (PC and other switching power supplies), or some other step. These spikes move with the VFO change.
Which one do you think you are experiencing? The methods to fight the interference depend a lot on whether it is AF or RF.
73, Mike AF7KR
