[Elecraft] RFI PC Speaker Hum

[Julian, G4ILO]

All computer speakers are amplified. Many of them have very poor immunity to
RF. I have sometimes reduced RFI to acceptable levels by winding a couple of
turns of the cables through snap-on suppression toroids. Winding several
turns through a large ring toroid would be more effective as the snap-on
suppressors are really only designed to suppress VHF.

Some computer speakers have such poor RFI immunity that they are probably
beyond fixing. One pair I bought made by Logitech hummed even when placed
near a cordless phone base unit that probably has an output power of a few
milliwatts. The first time I pressed the PTT of my transceiver the resulting
noise nearly gave me a heart attack. I gave them to a charity shop. There is
a firm (I think it may be the one that makes RigBlaster interfaces) that
advertises RFI-proof computer speakers, but I seem to recall the last time
they were mentioned on this reflector they were out of stock.

-----
Julian, G4ILO. K2 #392  K3 #222.
* G4ILO's Shack - http://www.g4ilo.com
* KComm - http://www.g4ilo.com/kcomm.html
* KTune - http://www.g4ilo.com/ktune.html

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