[TowerTalk] Computer RFI

[K8RI on TowerTalk]

ORIGINAL MESSAGE:

On Wed, 22 Nov 2006 22:50:39 -0500, "K8RI on TowerTalk"
 <K8RI-on-TowerTalk at tm.net> wrote:

>> Don't forget keyboard/mouse cables.  The keyboard cable in particular can
>> create some very nice hash.
>
>But that should go on and off with the computer. His goes on and off when
>the computer is plugged in.

------------ REPLY FOLLOWS ------------

>That depends on the computer power setup. Some keyboards and mice
>remain on so you can bring the computer out of standby by pressing a
>key or moving the mouse.

True.  This is what is known as "sleep mode" and is quite different from the 
off mode.
Sleep mode is sorta, kinda, similar to the screen saver mode and when turned 
on is usually set to kick in a bit after the system goes into screen saver 
mode.  In sleep mode there are a number of options which may vary from 
computer to computer.  In sleep mode the CPU *usually* remains running but 
at a greatly reduced speed and functionality.  The drives may or may not 
power down depending on settings, fans may or may not shut down, but usually 
do except for the CPU fan. IOW the computer has gone to sleep with only 
minimal sustaining life signs. A sleeping computer can be awakened by 
keyboard, mouse, USB,  and usually network input. (The CPU has to be running 
to be able to poll these inputs) This is really handy for a remote storage 
computer that you may need for backups a couple of times a night, but 
otherwise it really doesn't need to be running. However you don't want it to 
ask for the PW locally when it awakens if your back up computer is 200 or 
300 feet away through deep snow.<:-))

When the computer is off it is not sleeping. It's *almost* but not quite 
dead.  Unless unplugged or turned off the power supply is at least partially 
on and supplying *some* power to the motherboard.  The on/off switch 
initiates a logic sequence on the motherboard that turns on the rest of the 
power supply and the full motherboard functions.  The on/off switch is a 
momentary switch connected to the motherboard usually along with the HD 
light, power light, speaker, reset, and a couple other functions. OTOH the 
on/off switch on the PS is in the mains and it shuts the AC power off to the 
supply.  Some *really* cheap power supplies do not have that on/off switch 
but I've not seen one in years.


>I haven't had this problem, but I'd think you could unplug the
>keyboard and/or mouse to check if they are the source.

Good points.

Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com (Use return address from home page)

Bill, W6WRT