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AM radio noise

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Old 15-12-2007, 02:53 AM   #31
Vanguard
Guest
 
Posts: n/a
Re: AM radio noise

"Randy" <yksmir***********> wrote in message
news:6af26768.0307230111.5ddd7071@posting.google.c om...
> I've had this problem awhile but it seemed to be getting worse. My
> computer pretty much wipes out my AM radio (FM unaffected). All the
> wall sockets in my room are on the same circuit so I'm out of luck
> moving the radio. Now... I expect the AM radio to go bonkers if the
> system is on but this happens when the computer is off too. If I
> switch the power supply to off in the back of the case all is well. Is
> this normal?
>
> The graphics board always has a light on (Radian 9600 pro) for the 8x
> agp but I wouldn't think this would have that kind of affect. I hooked
> the computer up to a belkin surgemaster with a high frequency
> capacitor to no avail. I hooked my AM radio to the same surge
> protector and again zippo.
>
> Could the power supply be the culprit? If so are there ones on the
> market anyone could recommend that wouldn't contaminate the AC line of
> the house?
>
> Thanks
>
> Randy


Sounds like you need a line noise filter for your AM/FM radio, like at
Radio Shack (http://tinyurl.com/htqm). However, I don't think you can
use it for your computer as its function is to eliminate line noise from
the input side, not getting introduced from the output side. All other
devices will also be affected by the noise that your computer power
supply is putting on the line, so you might want to plan for a better
power supply.


 
Old 15-12-2007, 02:54 AM   #32
USA_Guy _
Guest
 
Posts: n/a
Re: AM radio noise

Sounds to me like a defective, or maybe just a very cheaply made power
supply.
-
~ Guy ~

 
Old 15-12-2007, 02:54 AM   #33
w_tom
Guest
 
Posts: n/a
Re: AM radio noise

Filter is not unidirectional. However a filter superior to
that Radio Shack product must be inside the power supply. Too
many computer experts don't even have basic electrical
knowledge. Therefore many clone computers have power supplies
selected only on one specification - price. It is called the
MBA mentality. Inferior power supplies can be dumped into N
America at even greater profit because too many N American
technicians don't even know what a power supply is suppose to
do - never read specifications - don't even have basic
electrical knowledge.

They are called low pass filters. They work in either
direction. Nothing technically advanced about that electronic
knowledge. Would be nice if Radio Shack gave even one
specification other than price. But then this filter, like so
many computer power supplies, is also being recommended
without any technical knowledge - no number or specifications
need be provided.

Buy a power supply for $40 that is missing many essential
functions including that low pass filter. Then spend another
$40 for every other appliance to filter the noise. This is
why cost controller mentalities cause major cost increases.
Until a minimally acceptable power supply is installed, then
all other solutions are wasted money and time.

Minimally acceptable starts at about $80. If noise is not
quashed at the source, then every wire connecting to that
computer becomes a potential transmitting antenna.

Noise filter is not required. The problem first must be
fixed. Solution starts with specifications.

"Vanguard " wrote:
> Sounds like you need a line noise filter for your AM/FM radio, like at
> Radio Shack (http://tinyurl.com/htqm). However, I don't think you can
> use it for your computer as its function is to eliminate line noise from
> the input side, not getting introduced from the output side. All other
> devices will also be affected by the noise that your computer power
> supply is putting on the line, so you might want to plan for a better
> power supply.

 
Old 15-12-2007, 02:55 AM   #34
jaster
Guest
 
Posts: n/a
Re: AM radio noise

Get a battery operated AM radio.

"Randy" <yksmir***********> wrote in message
news:6af26768.0307230111.5ddd7071@posting.google.c om...
> I've had this problem awhile but it seemed to be getting worse. My
> computer pretty much wipes out my AM radio (FM unaffected). All the
> wall sockets in my room are on the same circuit so I'm out of luck
> moving the radio. Now... I expect the AM radio to go bonkers if the
> system is on but this happens when the computer is off too. If I
> switch the power supply to off in the back of the case all is well. Is
> this normal?
>
> The graphics board always has a light on (Radian 9600 pro) for the 8x
> agp but I wouldn't think this would have that kind of affect. I hooked
> the computer up to a belkin surgemaster with a high frequency
> capacitor to no avail. I hooked my AM radio to the same surge
> protector and again zippo.
>
> Could the power supply be the culprit? If so are there ones on the
> market anyone could recommend that wouldn't contaminate the AC line of
> the house?
>
> Thanks
>
> Randy



 
Old 15-12-2007, 02:56 AM   #35
rcm
Guest
 
Posts: n/a
Re: AM radio noise

That won't work. I try to run a battery one near the computer and getting
within 5 ft generates interference. It is frequency dependent so it is much
stronger in the lower AM band.

Use Internet radio to listen I guess.




"jaster" <jaster@home.still> wrote in message
news:vgETa.2722$wc1.1452@newssvr31.news.prodigy.co m...
> Get a battery operated AM radio.
>



 
Old 15-12-2007, 02:56 AM   #36
V W Wall
Guest
 
Posts: n/a
Re: AM radio noise

rcm wrote:
>
> That won't work. I try to run a battery one near the computer and getting
> within 5 ft generates interference. It is frequency dependent so it is much
> stronger in the lower AM band.
>
> Use Internet radio to listen I guess.


There are two kinds of RF interference, conducted (usually through the
power lines), and radiated, directly through the air. PC cases are
supposed to shield against radiated interference, but openings in the case,
poor contact between side panels, etc. can negate this. As w_tom says,
the PS should have line filtering for conducted noise. (The FCC requires
units sold in the US to pass tests for this.)

All switching power supplies generate RF interference over a
fairly wide band. Even when "off", the ATX PS has a stand-by supply
that is constantly on when line power is supplied to the unit.

Since a battery receiver still has problems, it is a radiated RF
signal that is the culprit. You might try a better ground on the
computer case than that supplied by the line cord. Check for any
openings other than those required for air flow, and make sure these
have metal grills.

Wrapping the receiver in aluminum foil grounded to a water pipe,
might be a brute force way of stopping it's reception of the PS
radiated energy. You would then need an external antenna connected
by a shielded co-ax, as someone has suggested.The PS generated noise
is usually at about 40Khz, but it has strong harmonics well into
higher bands.

Virg Wall
--
Be not the first by whom the new are tried,
Nor yet the last to lay the old aside.
 
 

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