SEAN [G4UCJ/G4001SWL],

Grounding the Home (PC) Computer's Frame and Power Supply
- Does It Help ?
- Will It Work ?
- Could It Do Any Harm ?
To Reduce and/or Eliminate RFI / EMF Sound that are Heard
at various Frequencies on your Radios and Recivers.

A GOOD IDEA :
I just read your comments about Grounding the Home (PC)
Computer's Frame and Power Supply. And it started me to
Think (Warning) WHY NOT ? Can't Hurt and Just May Help !

STARTED BY :
Turning on three Radio/Receivers that are on the oposite
side of the room that has the Computer in it. Tuned for
what I thought was the 'best' RFI/EMF Noise or general
High Static Sound (Off Frequency Dead Spots) on the Radios.

TEST RADIOS, SET-UP AND CONDITIONS WERE :
* Icom IC-R75 on AC Power with Thirteen Foot (13') SWL
Coax Cable Loop Antenna in-the-room and a background base
Noise Level reading of 3 S-Units at 9.830 MHz with Pre-Amp
#2 Turned "ON".
* Sony ICF-2010 on AC Power with a Thirty Foot (30') SWL
Loop Antenna in-the-room and a specific 'hum' Noise Level
reading of 3-5 S-Units at 9.862 MHz.
* CCRadio +Plus using Battery Power and only it's internal
AM/FM Ferrite Rod Antenna and a specific 'buzz' Noise Level
reading of Two-Bars at 853 kHz.

GROUNDING THE COMPUTER FRAME AND POWER SUPPLY :
Examined the Back of the Computer and chose a Case Screw
that went througH the Metal Frame and into the Metal Body
of the Computer's Power Supply. Backed-Out the Screw and
attached a #14 Stranded Copper Wire and connected this
Wire to the Ground being used for the Radios.
The "Initial Test Results" We
* Icom IC-R75 = No Change in S-Meter or Sound Levels.
* Sony ICF-2010 = Slighly Higher +1 S-Unit reading
but the Audio "Hum" did not sound any louder.
* CCRadio +Plus = Much Higher Four-Bar reading and a
Higher Audio "Buzz" Sound.
[Suspected the Ground Wire was acting like an Antenna.]

FERRITE "DONUT" CORES :
Installed a Ferrite 'Donut' Core on both ends of the
Ground Wire about 3"-4" from each end.
The "Follow-Up Test Results" We
* Icom IC-R75 = Again No Change in S-Meter or Sound Levels.
* Sony ICF-2010 = Returned to the 'original' S-Meter reading
and the Audio "Hum" Sound was slightly less.
* CCRadio +Plus = Went Down to NO-Bars (Zero) and the
and Audio "Buzz" Sound was reduced greatly.

CONCLUSION {FUZZY LOGIC} :
What FIXES one Radio's Noise Problem; may have "No Effect"
on other Radios; and could Cause a New Problem for yet
another Radio. Not Very Scientific - But What Works... WORKS !
[You Have To Try It Yourself - To Find Out [.]
..
..
iane ~ RHF
..
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http://groups.yahoo.com/group/Shortwave-SWL-Antenna/
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I BELIEVE: On A Clear Night . . .
You Can Hear Forever and Beyond, The BEYOND ! ! !
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With the a Shortwave Listener SWL Antenna of your own making.
- - - If You Build It {SWL Antenna} You Will Hear Them - - -
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..
= = = In ,
= = = "Sean ()" g4ucj@t... wrote:

Some computer PSU's are fine, others are not. The one in
my shack PC generates no RFI hash, but the one in my main
PC throws up s9+ on 160 and 80m, using a mfj noise canceler
reduces it to a tolerable level but the only real way to
hear the weaker stuff is to kill the mains to the supply.

The only problem is you've got no real way of telling
what's going to be a quiet PSU and what isn't.


Perhaps grounding the metal case would help in some situations?
[ RHF - Note - The Light Bulb Goes "ON" Here :]

But I guess you would have to exercise caution when doing
something of that nature. One other source of noise can be
the displays on some radio's (the one on my 756 is quite
noisy).

Good luck and I hope it works!
73 de

Sean Gilbert, G4UCJ - G4001SWL