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Re: ways to tackle USB keyboard interference?

 

Hi Mike,

I took special note of your comment below about the USB interference, asone of my student designs <> had some annoying problems with this USB type interference.? It was significantly better with the super-cap USB smoother than without it, but it was still present, (lines in the waterfall about 1 KHz apart).? Thanks for your comment.

73,

Rob

KL7NA

On 6/7/21 2:06 PM, vbifyz via groups.io wrote:
CAUTION: This email originated from outside the Walla Walla University email system.


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



--
Rob Frohne, Ph.D. P.E.
E. F. Cross School of Engineering
Walla Walla University
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