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Re: [RFI] Keyboard RFI

To: rfi <rfi@contesting.com>
Subject: Re: [RFI] Keyboard RFI
From: Frank W3LPL <donovanf@starpower.net>
Date: Fri, 28 Jul 2023 02:12:43 -0400 (EDT)
List-post: <mailto:rfi@contesting.com>
Its poor EMC practice to bundle coaxial cables carrying transmitter
power levels with cables carrying low level signals.  Coax carrying
transmitter power levels should separated by at least a few inches
from cables carrying low level signals. More is better. Coaxial
cable cannot provide perfect shielding performance.

If for some reason you must bundle transmit level coax with cables
carrying low level signals, use silver plated double shielded coax
such as RG-400 or RG-214 for both low and high level RF signals.
But you should never expect perfect results when bundling together
high and low signal carrying cables.

73
Frank
W3LPL

----- Original Message -----
From: "K9MA" <k9ma@sdellington.us>
To: "rfi" <rfi@contesting.com>
Sent: Thursday, July 27, 2023 9:09:29 PM
Subject: [RFI] Keyboard RFI

I recently rebuilt my whole station. Among other things, I neatened up 
all the wires and cables. Naturally, this resulted in a bunch of new RFI 
problems. The latest is a malfunctioning usb keyboard. Wrapping the 
cable around the usual ferrite core seems to have fixed it. Here's the 
strange thing: The keyboard would sometimes malfunction not only when I 
was transmitting, but for some time after transmission had stopped, 
perhaps 10-15 seconds. It was as if the RF caused the keyboard to lock 
up, and it took some time to recover. Has anyone else seen such behavior?

73,

Scott K9MA

-- 
Scott  K9MA

k9ma@sdellington.us
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