[TangerineSDR] TangerineSDR Digest, Vol 27, Issue 3

Ward Silver hwardsil at gmail.com
Tue Jun 1 22:09:52 EDT 2021


Glad to hear of the insensitivity to ambient RF at a variety of
frequencies, Bill!

This brings up the system-level issue of RFI created by the PSWS as
conducted emissions, most likely.  It would be a problem if the PSWS
interferes with its own local receiver!  So we (meaning the design team)
will need to carefully evaluate the I/O and power lines to be sure they are
RF-quiet.  I can probably help with that as I am winding down a series of
back-to-back-to-back book projects and have some time coming up.

73, Ward N0AX

On Tue, Jun 1, 2021 at 9:00 PM <tangerinesdr-request at lists.tapr.org> wrote:

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> Today's Topics:
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>    1. Magnetometer RF testing, additional results (Bill Engelke)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 1 Jun 2021 16:15:00 +0000
> From: Bill Engelke <bill.engelke at ua.edu>
> To: TAPR TangerineSDR Modular Software Defined Radio
>         <tangerinesdr at lists.tapr.org>
> Subject: [TangerineSDR] Magnetometer RF testing, additional results
> Message-ID:
>         <
> BN8PR15MB31855B741907BD4C37902902FA3E9 at BN8PR15MB3185.namprd15.prod.outlook.com
> >
>
> Content-Type: text/plain; charset="us-ascii"
>
> Here is a follow-up to my last email regarding possible RF interactions
> with the magnetometer.  A couple of suggestions came in from the community:
>
>
>   1.  Ward Silver, N0AX, recommended to test by transmitting with a dipole
> near the magnetometer in several configurations, on 2 meters with 50 w.
>   2.  Tom McDermott, N5EG, recommended to look for RF noise being
> generated by the magnetometer that might get into your station receiver.
>
> Here are results of doing such tests:
>
>
>   1.  I built a 2-m dipole specifically for this so that I could test with
> the antenna (a)broadside to the magnetometer, (b)vertical to it, and (c)
> pointed towards it. (photos) The antenna was located about 10 feet from the
> magnetometer, which is buried at 2 feet in the soil (its standard
> installation as tested by Jules and others), and connected to the station
> with shielded CAT-6.
>
> Broadside configuration
>
> [cid:image004.png at 01D756D6.2EB4CD30]
>
> Vertical configuration:
>
> [cid:image005.png at 01D756D7.049AA500]
>
> Straight-on configuration
>
> [cid:image006.png at 01D756D7.049AA500]
>
> The antenna was connected via a new 50 foot RG-8 cable to an Icom
> IC-706MKIIG, set to high output (50 watts), 145 MHz. I did my best to do
> what Ward suggested.
>
> Results: I never saw the magnetometer readings change when I keyed the
> rig; this was the same for the 3 different antenna angles. I have to
> conclude that the magnetometer is not sensitive to 2 meters.
>
>
>   1.  Using the FlexRadio 6600, I looked for noise being generated by the
> magnetometer on all ham bands from 160 m to 10 meters. I looked for wide
> band noise by watching the waterfall and turning the magnetometer on and
> off. If I saw noise appear, I tried turning the magnetometer off and on to
> see if the noise would come and go with being connected to the magnetometer
> base card on the Raspberry Pi. I used the appropriate antenna for each band
> (i.e., the one I use for my station), as follows:  (160 M) - multiband
> vertical, (80M) halfwave dipole at 15 ' (20 feet away) and also multiband
> vertical about 50' away, (60M) multiband vertical, (40 M) double bazooka
> inverted vee, (20M through 10 M) DX Engineering Hexbeam on 50' tower.
>
> Results: First the good news: I never saw wideband noise attributable to
> the magnetometer on the bands 60 meters and higher in frequency.   I did
> see noise on 80M and on 160M.  The magnetometer does generate noise of
> about 0.4 db as shown on the FlexRadio s-meter on 80M. (Note that this is a
> severe case, as the 80 M dipole is only up 15' and about 20' away from the
> magnetometer - but this is probably a typical situation). On 160 M, the
> magnetometer generated 1 db of noise.
>
> Screenshot of 80 M result using dipole
>
> [cid:image001.png at 01D756D4.9FD34E80]
>
> Screenshot of 80 M on multiband vertical
>
> [cid:image002.png at 01D756D5.12202BC0]
>
> Screenshot of 160 M, multiband vertical
>
> [cid:image003.png at 01D756D5.6F866360]
>
> I suppose that we would recommend turning off the magnetometer if you are
> working DX on 80 Meters; possibly separating the magnetometer from the
> antenna might also help, but I was not able to test that.
>
> -73- Bill,   AB4EJ
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> End of TangerineSDR Digest, Vol 27, Issue 3
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