[Lowfer] PC noise source; I was surprised

[John RABSON]

Andy,

I am surprised at experience with an HP product.  My experience with things from HP has always been (i) they cost a bit more but (ii) they always work correctly.

The practice of manufacturers leaving out filter components in power supplies has been discussed recently in the EMC column in RadCom.  I am forwarding your comments to their EMC specialist, G0SNO.

John Rabson 
F5VLF
58800 Cervon
France
JN17vg

*********** REPLY SEPARATOR  ***********

On 26/01/2010 at 19:54 Andy - KU4XR wrote:

>Hi everyone:
>
>My PC noise woes are no longer a problem. And when I found the
>problem, I got a bit ticked off. I spent a pretty penny on the
>ORION power supply from HP in the UK. Advertising had it hyped
>up to be a super Industrial type power supply. Clint described 
>it in his post. The frazzlin thing had NO::: input filtering
>whatsoever, not a stitch. All the places for the components
>were on the board, but when manufactured; the caps were left
>out, and where the chokes were supposed to be was bypassed with
>with straight wire. I brought home 3 power supplies from work
>to switch out, and a dead one for parts. SMPS have always made
>me a little leary about working on them, but I figured what the
>heck, it'll either go, or blow. I took the input filter parts
>from the dead supply, and installed them in the ORION supply.
>Plugged it in the outlet, no kaboom, flipped the switch on the
>supply, the light dimmed for a split second; but no kaboom.
>And finally the smoke test, pressed the power button on the PC
>and::: no kaboom, just a nice boot up, and heavens to betsy !!
>no noise !!!! I tuned around and found the noise still there
>but down at 497.80 KHz, AND !! dropped 20dB in intensity.
>No noise in the lowFER band, ran the ham bands thru 30 meters,
>and just a couple of very narrow spots on 160, and 80 meters,
>none on 40 meters, and 30 meters was as quiet as if the PC was
>turned off.
>
>A couple of other tid-bits; - - before fixing the power supply;
>I replaced every power cord in the house with the shielded ones,
>and it did make a difference actually to my surprise. No more
>TV hash now, and all PC's but my daughters made no noise.
>I forgot that I had put the same ORION supply in her PC too.
>I swapped it with one I brought home that was well filtered,
>and had the shielded AC input plug. Turned her PC back on,
>and Wah-Lah !!! noise gone !!!  I'm sitting here now looking
>at the S meter and seeing the lowest noise level ever with
>3 computers, and a HDTV set going. 
>
>Gentlemen; again I want to say thank you for the wealth of
>information you guys have shared with me while trying to find
>the culprit. Now, I am looking forward to actually doing some
>listening with a chance of hearing something.
>
>73 to all from Friendsville, TN.
>
>
>Andy - KU4XR - EM75xr - Friendsville, TN.
>LOWfer Beacon " XR " @ 185.29866 KHz ( QRSS-60 )
>Coordinates:  N:  35* 43' 54" - W:  84* 3' 16"
>http://www.myspace.com/beaconxr
>http://webpages.charter.net/ku4xr/
>
>
>      
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