[RFI] Noisey PSU (Laptop) on HF Decodeing

[Fred Stevens K2FRD]

I absolutely agree that it is seldom a simple issue with RFI. It also occurs to me that my newest Mac which causes the most RFI is also equipped with a wireless card meaning it also has an antenna (located around the perimeter of the lid) which then makes radiation of any RFI which comes into the laptop that much more pervasive (all three laptops are located within 6" to 18" of my TS-2000 - any computer-generated RFI is almost a hardwired feed). The other two, older laptops are not so wi-fi antenna equipped. The old Dell is perfect for digital as long as I keep it on battery instead of commercial power (to which I have been connected only once in four years as a fulltime RVer; I'm usually on generator or solar power, but that's yet another issue: boondocking RVs and RFI).

73 de Fred K2FRD

At 8:36 PM -0400 29/5/07, Tom Rauch wrote:
>
>But of course we all know it takes two to tango!!!
>
>Not only must the PS make noise, the noise must somehow get into the receiving system.
>
>Every fast efficient switching supply in the world makes noise, but how much it bothers our stations depends on our antennas as much as it does the supply. It depends on how the feedlines are decoupled for common mode, how far the antennas are away, the local noise level, the receiver bandwidth we use, ambient noise levels around the site, and many other things.
>
>Unless you can refer each PS to a uniform measurement standard of coupled noise into the power mains, what works in one place is largely meaningless somewhere else.
>
>A big problem when using computers for interfaces with radios is you are just begging for setting up common mode ground loops that aggravate the whole thing, especially when a station has a poor wiring layout for ground loops and common mode on antenna feedlines.
>
>It is just as important to describe the antenna as it is the computer.
>
>73 Tom


-- 
73 de Fred Stevens K2FRD, VO2FS
http://homepage.mac.com/k2frd/K2FRD.html