[CQ-Contest] Computer RFI

VR2BrettGraham vr2bg at harts.org.hk
Thu Dec 29 20:27:28 EST 2005

N5OT mentioned:

>Anyway, I had also noticed the sound of the RFI changed with the colors
>being projected on the monitor (I never tried changing refresh rates).
>Naturally, switching the monitor off and on and hearing the noise go away
>and come back can prove it's the monitor.
>Which brings me to my most interesting latest bugaboo - the noise with the
>LCD monitors - the noise wouldn't go away when I switched off the monitor,
>but it would change in sound and frequency.  It WOULD go away when I
>unplugged the rectangular black outboard switching power supply.

Although originally due to desire to keep station on-air during loss
of mains power, by selecting stuff with these external supplies that
run on 12 volts DC, everything runs off a nice, big & most importantly
quiet linear supply along with antenna switching & other stuff in the

73 & HNY/HLNY, VR2BrettGraham

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