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USB 3 hubs are RF noisy?


 

I heard from a ham that I should be using USB 2 hubs in a ham project because USB 3 hubs were too RF noisy.
Is there anything to this?

Thanks! DE Tadd KA2DEW

Raleigh NC


Matt 9V1MH/VK3AMH/YF2AAH
 

All hubs are noisy 2 & 3
thinks of it this way (assuming your computer/laptop) is well shielded (most are not)
you take a cable and take a data stream outside the computer/laptop which has all sorts of EMF generating parts inside it
the data stream is essentially an on/off stream (1's & 0's) at varying frequencies - think CW at 1000 words per minute or more
the cable is probably not well shielded or protected with chokes of some sort
the usb hub is probably made of plastic - again not shielded
so you have a pulsed data stream at somewhere from 400MHz to 5GHz on an unshielded cable and inside an unshielded box

pretty much everything to do with computers generates some sort of EMF from your monitor, to your fancy lit up keyboards to your Bluetooth (just RF really) mouse to your wifi connection to the computer/laptop/raspberry to the power supply of the units - switchmode

not only do they emit EMF - they are also susceptible to EMF (RF) getting into the units through all the attached cables and plastic cases they are contained in.

and don't just think of the computer - any plug-pack (wall wort) is a switch mode power supply - your printer - your TC - your sound system - and a huge range of other electronic systems in your house also emit "noise"


Ham Radio
 

The other thing to consider about EMI is the quality of the USB cable.  There are a lot of “junk” cables sold.  I suspect the shielding is rather poor in a $1 cable.  I know for sure from testing, that some USB cables can not even source 1 amp to charge a tablet. Testing various USB cables for RFI/EMI would make a good project for a student or experimenter ...

U
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73, Bernie.   VE3FWF