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Re: [RFI] A source of RFI

To: rfi@xxxxxxxxxxxxxx
Subject: Re: [RFI] A source of RFI
From: "Roger (K8RI)" <k8ri@xxxxxxxxxxxxxxxxx>
Date: Tue, 30 May 2017 06:20:55 -0400
List-post: <mailto:rfi@contesting.com>
I know this sounds trite, but get a good computer. I'm running two monsters in full size, steel tower cases within 3 feet of the rigs, USB cables and standard serial cables (com1 and com 2). I have no interference and no chokes on any of the lines. The 75/40 sloping dipole is about 60 feet from the computers. O Desktop computers (PCs) typically use plastic cabinets and inexpensive power supplies. The same goes for network interface cards.

It's often not just the cables that radiate, but the computer itself with the plastic cabinet makes for no attenuation to signals from inside the computer. Jim Brown (K9YC) has an excellent page on grounding and choking, but with plastic cases...who knows.

Antennas are 60 feet of more distant, but a fire in the RX coax connector doesn't hear the computers either.

73, Roger (K8RI)

On 5/29/2017 Monday 1:21 PM, JW via RFI wrote:
Ken,

Kinda more or less known; different screen refresh and or resolutions have been known to 
"shift" those frequencies too. If a fave freq is blocked by a birdie, try 
making a change in the above mentioned parameters.

Jim WB5WPA


       From: Kenneth G. Gordon <kgordon2006@xxxxxxxxxxxx>
  To: RFI@xxxxxxxxxxxxxx
  Sent: Monday, May 29, 2017 12:07 PM
  Subject: [RFI] A source of RFI
Hmmm...well, yesterday, I found that a source of RFI on (at least) 40 meters is the desktop
computer sitting on my operating bench. RFI changes with changes in the "scene" 
on the
screen.

Turning off the 'pooter resulted in noise level dropping to S-1 (transceiver in 
narrow CW) on
selected frequencies.

I'm not sure at this point how to fix this, but I'll be working on it.

What brought it to my attention was a weak but steady carrier on 7053, which 
would
disappear when I changed to a different piece of software on the 'pooter.

Sigh.... :-(

If it isn't one thing, its another.

Ken W7EKB

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