My new plastic sided (gamer?) 2.8 GHz PC causes not a single problem here in
the shack. My older 400 MHz Celeron however totally trashes 80 meters and is
only tolerable on 40 meters, everything else is fine. Go figure.

Sam

Ken Bessler wrote:
The following website has a 1M .mp3 file of some QRM
I'm getting on 160 meters. A little background is in order:

My station has my PC about 3' away from my FT-857D's.
I've eliminated all cables except video so I'm pretty sure it's
not coming from them. I've powered off my monitor and
adjusted the refresh rate to no avail. I grounded the PC's
metal case and tried it with/without the side covers. No
difference in the signal.

Tonight I looked at my CPU temp and it was a tad higher
(127 deg F) than normal so I decided to turn on a box
fan pointed at the left side of the tower case. To my shock,
the QRM faded away! I switched the fan on and off several
times to prove my theroy. Then I made the mp3 recording you
can download he

http://members.cox.net/kg0wx/index.html

Listen closely to the sound - at 2.2 seconds into the rec-
ording, you can hear the "tick" that is me turning on the
fan to "low". Within a few seconds, the QRM is gone!

Anybody know where I should look to find this and kill
it?

I had a similar problem with a new computer system I recently built up.
Problem was a noisy 350W Power Supply.

I replaced it and the machine now is perfectly quiet. A good solution
for a few bucks. It is very hard to shield a computer from this sort of
noise as it radiates from the leads in addition to directly from the case

Dick K7RNZ

Ken Bessler wrote:


It's a big honkin' $5 Wal-Mart special - taller than the PC so
I mounted the tower on stands to put the MB right in the flow
of air. The CPU is a 1.4g Athlon (not over clocked).

I've played with how far the exhaust side is away from a wall
- at 12" most of the air just blew by the components and my MB
and PS temps were not very low. Placing the right side of the
case 1" from the wall created enough back pressure to drop
both another 5-10%.

For the record I have a 2 fans on the case, 1 on the CPU and
1 on the power supply. My video card is a bit low end (Nvidia
G-force Ultra 8 meg) and has no fan. I have 340 gig of space
on 3 Westerd Digital HD's that want to run hot but with this big
box fan, are nice & cool now.

I'm thinking it's the video card......


Hummmm. I was thinking the CPU fan or the controller...Most
CPU fans vary speed as per CPU temp. It sort of sounds like
the CPU is getting hot, and the MB is telling the fan to speed
up. I was thinking either the controller is causing the noise,
or the fan itself starts to make more noise at the higher speeds.
Does the MB read fan speeds? You might look to see if the fan
speeds follow the noise. I'm not sure about any AMD "throttle back"
modes when overheated, or if that could cause more noise...
I'm having trouble seeing how the video card would increase noise,
just by being hot. Seems it would have to vary clock rate,
display types, res, etc, to change noise...What I would do is
unhook the CPU fan, and use the box fan only as a temp fan.
Then run it until it gets up to that "noisy" temp, and see if
it still does it. If so, it's likely the MB itself...If not,
it was likely the fan itself. If thats the case, it's probably
an easy fix, by using a different fan. As far as the video card,
I guess thats harder to pin down...Unless you have a 2nd card
you can sub out...If I ended up suspecting the video card, I would
install a small fan on it. They make tiny ones for this purpose..
But....I'm still having a bit of trouble seeing it as the video...
I'm kinda leaning to the fan, or it's MB controller...
Wanna talk hot CPU's? I'm running a P4 "prescott" chip...*Thats*
a hot running CPU...I use a CPU fan, a fan under the hard drives,
a big 110v fan on the side of the open case, and the PS fan...
Sounds like a 737 at the gate... I don't run a closed case here.
My CPU gets too hot for my tastes if I do...
Mine is all open, with AC filter material as the sides...
I get lots of dust buildup due to all the fans going 24/7...
The Prescotts require the ambient temp in the case to be 38c,
or less..The prescotts do have a throttle back mode at 70-75c I
think, and I can set one myself in the BIOS at any temp...
Mine varys what it does...Gets the hottest running the flight sim...
Maybe 52-55-58c average...Depends on the room temp...Right now,
playing usenet, it's at 45.5c.."113.9f"...BTW, if it's the MB, I
guess all you can do is just add cooling so it doesn't ever run hot
enough to go into the higher speed modes. The fan on mine is a intel
fan, and it varies gradually, not in steps..If it gets hotter,
it just gets slowly faster and faster...I've never noticed any noise
from it..But your's may be different..
MK

wrote in message
ups.com...

Hummmm. I was thinking the CPU fan or the controller...Most
CPU fans vary speed as per CPU temp. It sort of sounds like
the CPU is getting hot, and the MB is telling the fan to speed
up. I was thinking either the controller is causing the noise,
or the fan itself starts to make more noise at the higher speeds.
Does the MB read fan speeds? You might look to see if the fan
speeds follow the noise. I'm not sure about any AMD "throttle back"
modes when overheated, or if that could cause more noise...
I'm having trouble seeing how the video card would increase noise,
just by being hot. Seems it would have to vary clock rate,
display types, res, etc, to change noise...What I would do is
unhook the CPU fan, and use the box fan only as a temp fan.
Then run it until it gets up to that "noisy" temp, and see if
it still does it. If so, it's likely the MB itself...If not,
it was likely the fan itself. If thats the case, it's probably
an easy fix, by using a different fan. As far as the video card,
I guess thats harder to pin down...Unless you have a 2nd card
you can sub out...If I ended up suspecting the video card, I would
install a small fan on it. They make tiny ones for this purpose..
But....I'm still having a bit of trouble seeing it as the video...
I'm kinda leaning to the fan, or it's MB controller...
Wanna talk hot CPU's? I'm running a P4 "prescott" chip...*Thats*
a hot running CPU...I use a CPU fan, a fan under the hard drives,
a big 110v fan on the side of the open case, and the PS fan...
Sounds like a 737 at the gate... I don't run a closed case here.
My CPU gets too hot for my tastes if I do...
Mine is all open, with AC filter material as the sides...
I get lots of dust buildup due to all the fans going 24/7...
The Prescotts require the ambient temp in the case to be 38c,
or less..The prescotts do have a throttle back mode at 70-75c I
think, and I can set one myself in the BIOS at any temp...
Mine varys what it does...Gets the hottest running the flight sim...
Maybe 52-55-58c average...Depends on the room temp...Right now,
playing usenet, it's at 45.5c.."113.9f"...BTW, if it's the MB, I
guess all you can do is just add cooling so it doesn't ever run hot
enough to go into the higher speed modes. The fan on mine is a intel
fan, and it varies gradually, not in steps..If it gets hotter,
it just gets slowly faster and faster...I've never noticed any noise
from it..But your's may be different..
MK


My MB is a Shuttle AN35 Ultra (about 3y old) and it does
read fan speed (5443 rpm now) but it does not adjust fan
speed afaik.

One of these days I'll get curious and pop off a case fan and
point it at various components while listening to 160m.......

--
73's es gd dx de Ken KGØWX
Grid EM17ip, Flying Pigs #1055,
List Owner, Yahoo! E-groups:
VX-2R & FT-857