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<p class="MsoNormal">Alan – with<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo4">The magnetometer buried at 2 feet depth<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo4">Running shielded CAT6 cable grounded at the R-Pi<o:p></o:p></li></ul>
<p class="MsoNormal">I have tested (with the magnetometer running at recommended parameters) on 160 M through 10 M (at 1 KW), on 6M (at 500W) and on 2M (at 50 W) and so far I have not seen any perturbations of the magnetometer from carriers at these bands &
power levels.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">It has been suggested to me that I try doing some modulation and see if that makes a difference; I still have to run that s of tests. -73- Bill, AB4EJ<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b>From:</b> TangerineSDR <tangerinesdr-bounces@lists.tapr.org>
<b>On Behalf Of </b>n5pa via TangerineSDR<br>
<b>Sent:</b> Wednesday, June 30, 2021 2:39 PM<br>
<b>To:</b> TAPR TangerineSDR Modular Software Defined Radio <tangerinesdr@lists.tapr.org><br>
<b>Cc:</b> n5pa <n5pa.dx.341@gmail.com>; Bill Engelke <bill.engelke@ua.edu><br>
<b>Subject:</b> [EXTERNAL] Re: [TangerineSDR] Getting rid of magnetometer-related RF noise<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt">Good info to know Bill! I run QRO on most bands and I am concerned about getting into the magnetometer, also.<o:p></o:p></p>
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<p class="MsoNormal"><b><i>73,</i></b><br>
<b><i>Alan Clark, N5PA<br>
</i></b>Ellisville, MS<br>
Email: <a href="mailto:n5pa@n5pa.com" title="mailto:n5pa@n5pa.com">n5pa@n5pa.com</a><br>
URL: <a href="https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.n5pa.com%2F&data=04%7C01%7Cbill.engelke%40ua.edu%7C6b803b5bdba9466007b308d93bfee3a9%7C2a00728ef0d040b4a4e8ce433f3fbca7%7C0%7C0%7C637606788214030979%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=IiYe6jSmasEixXVMkrtZN5syd81aSudnMee2jYMfr8g%3D&reserved=0" title="http://www.n5pa.com/">http://www.n5pa.com</a><o:p></o:p></p>
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<o:p></o:p></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal" style="margin-bottom:12.0pt">On Jun 30, 2021, at 1:25 PM, Bill Engelke via TangerineSDR <<a href="mailto:tangerinesdr@lists.tapr.org">tangerinesdr@lists.tapr.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">To all:<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">You might recall that a few weeks ago I discovered some RF noise appearing on 160 M and 80 M when the magnetometer was hooked up. This was wideband noise on 80M and a birdie on 160M.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Note that I have been using shielded CAT6 cable between the magnetometer base (a Pi-Hat) and the in-ground magnetometer. The noise could be seen clearly in the waterfall on my FlexRadio 6600 connected to my 80M dipole; it was only 1 to
2 s-units, but this might be an issue for DXing.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">It required 2 steps to eliminate this noise:<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<ol style="margin-top:0in" start="1" type="1">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l2 level1 lfo3">The ground plane of the R-Pi needs to be connected to an earth ground. This eliminates the birdie on 160M and cuts the 80M noise about in half. Do this by grounding the sleeve of the
R-Pi audio jack.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l2 level1 lfo3">The remaining 80M noise is due to the Canakit switching power supply that comes in a Raspberry Pi kit. To eliminate that, you must replace the switching power supply with a linear
power supply. I found a 4.5 amp linear supply (Pyramid brand, on Amazon $55.79) that has 2 USB jacks (each able to supply 2 amps) plus 13.8 V terminals.*<o:p></o:p></li></ol>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">-73- Bill, AB4EJ<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.25in">* There are cheaper linear power supplies, but R-Pi recommends a supply able to provide 3 amps. Linear power supplies able to provide 3 a are not plentiful or cheap. I measured the actual current pulled by a R-Pi
4 B+, and it is around 1 amp. With the Pyramid supply I am powering two R-Pi 4 B+ computers with power to spare, and the switching noise is gone.<o:p></o:p></p>
<p class="MsoNormal">-- <br>
TangerineSDR mailing list<br>
<a href="mailto:TangerineSDR@lists.tapr.org">TangerineSDR@lists.tapr.org</a><br>
<a href="http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org">http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org</a><o:p></o:p></p>
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