Re: Portable SWL setup with Airspy HF+ and GPD Win #hardware #airspyhfplus #swl #shortwave

London Shortwave

Roughly a decade ago, I did a home automation system which included Class-E audio amplifiers for EMC/RFI.  The Class-E amps turned out to be especially dirty for radiated emissions.  They are efficient, but all that efficiency goes to producing all kinds of RF hash and just contributes further to the RF fog.  
On one of my laptops, I finally designed, built, and installed a 5-section Chebychev LPF to install in series with the charging port.  Problem was inside the laptop, not the switcher which provided charging power.  Trouble is on a laptop, what return does any specific function within the digital wonder reference?  For the audio input to one of the laptops that runs 365/24/7 on radio astronomy, I've tied the conductive backshell of the Video connector to the  (isolated) 'return' (ring) of the 1/8" stereo phono plug.  Also, you will soon discover the touch pad on most laptops introduces a lot of HF RF noise by itself.  And try holding you hand near (usually the lower right bottom) of about any touch screen while listening to HF.   In the USA, where is the FCC?
However, I must give Microsoft credit for their Surface.  It's a touch screen, but exceptionally quiet in terms of RFI.  I love the thing!
Dave - WØLEV    
Thanks Dave,

I agree, in my experience, on Atom tablets it seems the most common sources of interference are the touchscreen displays and built in speakers.

Cheers, LS

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