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Re: [perseus_SDR] Laptop Induced Noise

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  • Tim Hall
    This topic of laptop noise is important, and keeping a database of people s experiences would be helpful. (Laptop noise is certainly not Microtelecom s fault,
    Message 1 of 81 , Sep 3, 2013
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      This topic of laptop noise is important, and keeping a database of people's experiences would be helpful.  (Laptop noise is certainly not Microtelecom's fault, of course, but we still have to work around the issue if we're going to be successful... and that can be very dicey, as some of us have already experienced).
      For the record, I have a Lenovo T420 (actually my work laptop) and the noise/attenuation makes the Perseus essentially unusable, on battery or AC power.  While I was typing this, I saw a message come in from someone who had the exact opposite experience with a T420.  So even for the same model, it looks like results can vary widely.  That gives me hope, since my T420 is dying and they're going to replace it soon.  The Perseus works great from my home PC (an old Gateway tower running XP) sitting right next to the laptop and using the same antenna, so I've ruled out "operator error" at this point :)
      73 Tim
      On Tue, Sep 3, 2013 at 9:54 AM, Werner Karn <werner.karn@...> wrote:


      my experience is that in most cases the noise is coming from the switching power supply. You can easily check yourself with Perseus using a coax cable with a little wire loop at the end (diameter appr. 10 cm ) and putting it close the suspect devices using the
      HFSpan software. I found this the best way to finding a quite AC adapter.



      Am Dienstag, 3. September 2013 schrieb Anthony R Gargano :

      Bought a new Perseus and didn't want to clutter up my Macs with Windows. I was given an HP laptop that's about 5 years old with a Core 2 2GHz CPU, a dead battery (only works when connected to AC) and 2 dead LCD display lines. I wanted to use it just to check out the Perseus before I pick up a Windows laptop or possibly a Surface Pro.

      The new Perseus itself works fine but this HP laptop is a real noise generator. I isolated the noise to the HP using a portable receiver. The noise disappears upon disconnecting the HP's power cable. Since the battery is dead I can't tell if the noise is coming from the laptop itself or the AC adapter which is bound to be some sort of switching supply.

      Now for my question to those of you using your Perseus with a Windows laptop or tablet: are there known models to stay away from because of noise problems? Conversely, what noise free laptop or tablet are you using that you are happy with?
      Thanks for any comments or help,

      Anthony R Gargano


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    • Mark Clark
      Have you tried wrapping the input and output cables from the laptop power supply with toroid chokes? I ve had good success quieting PC noise that way for many
      Message 81 of 81 , Nov 3 11:13 AM
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        Have you tried wrapping the input and output cables from the laptop power supply with toroid chokes?  I've had good success quieting PC noise that way for many years. 

        73, Mark N3IRJ
        On 9/4/13 2:47 PM, N9OVQ wrote:

        And just to complicate matters further ... I use an HP Pavilion g series
        laptop. It is whisper quiet at my primary QTH, where my Wellbrook loop
        is mounted 35 feet from the house and everything in the shack is
        grounded. At my condo in Chicago, however, the same laptop is noisy,
        although I am using a third-party power supply and the Wellbrook loop is
        installed only 8-feet away from the building. Fortunately, the noise
        disappears when I run the laptop on batteries, so that is how I use the
        Perseus when I DX from downtown Chicago.

        Mike Nikolich - N9OVQ

        Mark N3IRJ
        Reinholds, PA
        Perseus SDR/G5RV/Wellbrook Loop/Mestor for unattended recordings
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