K7S5A radio noise

On Tue, 08 Jul 2003 21:47:45 GMT, Jam <kb6rxe.TakeThisOut@pacbell.net> wrote:

 >I put together a $90 Fry's special K7S5A/Athlon 2400+ last week. I used
 >a $28 case with a 450 watt PS I bought at at the TRW ham radio swap
 >meet. I put in 256MB of PC2100 for $26.
 >
 >The system booted right up and runs great, but I get a lot of noise on
 >the radio. My other systems
 >are based on FIC 503+ and Abit BX6 motherboards with K6-III+ and PIII
 >cpus and they
 >don't generate much radio noise.
 >
 >Is it the cpu, the motherboard or the power supply that generates all
 >the noise?
 >What can be done to reduce the noise?
 >
 >My radio is an ICOM 735 ham radio connected to a 5 band trapped vertical
 >antenna
 >mounted outside on the roof. I listen to a lot of AM commercial radio on
 >this system
 >and some ot fhe lower powered local stations get wiped out when I turn
 >on the K7S5A
 >system.

The monitor vertical sync generates most of the HF noise in my system.
Check the Control Panel / Display / Advanced / Adapter and see if you
hav a choice of Refresh Rate settings. It depends on the video card
and monitor combination in your system. I am able to adjust mine
between 60 and 100 Hz and can usually eliminate the interferance on a
given receive frequency by trying different settings.

73, WB0MOT<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: K7S5A radio noise 

In the BIOS there is a setting called Clk Gen Spread Spectrum and I believe
it has something to do with 'noise'.
Try setting it to 'Enabled'. It is the Advanced Setup section.
Don't know if it will help or not.


"Jam"
 > I put together a $90 Fry's special K7S5A/Athlon 2400+ last week. I used
 > a $28 case with a 450 watt PS I bought at at the TRW ham radio swap
 > meet. I put in 256MB of PC2100 for $26.
 >
 > The system booted right up and runs great, but I get a lot of noise on
 > the radio. My other systems
 > are based on FIC 503+ and Abit BX6 motherboards with K6-III+ and PIII
 > cpus and they
 > don't generate much radio noise.
 >
 > Is it the cpu, the motherboard or the power supply that generates all
 > the noise?
 > What can be done to reduce the noise?
 >
 > My radio is an ICOM 735 ham radio connected to a 5 band trapped vertical
 > antenna
 > mounted outside on the roof. I listen to a lot of AM commercial radio on
 > this system
 > and some ot fhe lower powered local stations get wiped out when I turn
 > on the K7S5A
 > system.
 >
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: K7S5A radio noise 

On Tue, 08 Jul 2003 21:47:45 GMT, Jam <kb6rxe DeleteThis @pacbell.net> wrote:

 >I put together a $90 Fry's special K7S5A/Athlon 2400+ last week. I used
 >a $28 case with a 450 watt PS I bought at at the TRW ham radio swap
 >meet. I put in 256MB of PC2100 for $26.
 >
 >The system booted right up and runs great, but I get a lot of noise on
 >the radio. My other systems
 >are based on FIC 503+ and Abit BX6 motherboards with K6-III+ and PIII
 >cpus and they
 >don't generate much radio noise.
 >
 >Is it the cpu, the motherboard or the power supply that generates all
 >the noise?
 >What can be done to reduce the noise?
 >
 >My radio is an ICOM 735 ham radio connected to a 5 band trapped vertical
 >antenna
 >mounted outside on the roof. I listen to a lot of AM commercial radio on
 >this system
 >and some ot fhe lower powered local stations get wiped out when I turn
 >on the K7S5A
 >system.
 >

Time to swap out stuff or use a portable radio and stick it next to
everything. Then start filtering.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: K7S5A radio noise 

On Tue, 08 Jul 2003 21:47:45 +0000, Jam wrote:


 > Is it the cpu, the motherboard or the power supply that generates all
 > the noise?
 > What can be done to reduce the noise?

I have a K7S5A/Athlon XP2100+ running in my radio shack.
I'm happy to report that it makes no RF noises on any
band from 160M up to 2M.

If you have a well screened metal case, most of the
interference is probably radiated by one or more of
the various wires coming from the back of the case.
Try disconnecting all peripheral devices one at a time.
The monitor is a likely source of RF interference. Remove
the mouse, ethernet cables, telephone line, even the
keyboard if the machine will boot without it. If all
of this fails to improve the situation, the noise is
probably from the PSU. Try some large clamp-on ferrite
cores on the mains supply lead. Put them as close to
the case as possible. It is relatively easy to filter
out noise on the higher frequency bands, but it can be
quite tricky to get rid of interference on MW or LW.

Your trapped vertical may share a common ground connection
with your PC. Try using different mains sockets for the
radio and PC. Try using a mains lead with a built-in
RFI filter.

Good Luck.

73, Ed. EI9GQ.


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 >> Stay informed about: K7S5A radio noise