n6gn
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IMO you are missing something. Necessary to remove CM <==> differential coupling (asymmetry) in the antenna system. CM ground currents, and asymmetry mean that unwanted noise degrades the desired antenna signal. A balanced dipole or loop st…
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I concur that a single metric such as obtained through an SNR algorithm is not a good tool to use for evaluation in real life situations. I further agree that human examination of spectra, particularly broad bandwidth ones with an eye on noise signa…
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It was a filter built in a 50 ohm context, as demonstrated by 50 ohm SMA connectors. The lines from the connectors to the filter are not 50 ohm but something a good deal higher Z. Relatedly the lines between even his physically isolated resonato…
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He would have done even better to pay attention to making the 50 ohm traces, indicated by the presence of the 50 ohm SMA, be 50 ohms. For FR4 that probably indicates a width/height of a bit under 2. https://forum.kiwisdr.com/uploads/311/EG29BNQFOX…
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I'll leave it to Martin since I know little about MFJ-1886X but it appears that not only are signals very low but that there are very few below mid-HF. Since most places in the world have AM or MW broadcast stations nearby, it rather looks to me lik…
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As both Martin and I have been suggesting, please present a spectrum plot so any similarly spaced lines, particularly down near the low end of a Kiwi's range, might be discovered. Very low frequency ingress will not be by way of (inverse square) …
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OK. 'unwittingly disrupts" and "for the wrong reasons" can speak to the same mechanism(s). But the added preamp itself can be that method.
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This seems to be a characteristic spectrum of a 15 kHz impulse or perhaps high odd harmonics of a 7.5 kHz square wave. These kinds of signals are often from fast edges of SMPS power sources coupling into receive systems. If you could forego the …
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Martin The differentiating point I was trying to make is about 'local environment' You wrote that further improvement can only be improved by using a better antenna. I was trying to make clear that there can be and usually are multiple causes for…
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Martin writes: "If it is 6dB or more, then your system is already noise limited by your antenna and local environment, and this may be the best you can achieve. Any further improvement can only be brought about by using a better antenna, or by …
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If you use a broadband display, particularly one with min/max hold you can appreciate where the QRM is by the ham-band notch depths as well as how much it is hurting your SNR. Here is capture of reverse channel, user ==> Internet, Internet-ov…
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"Well, its quite interesting that just moving the antenna a few feet, seems to increase the SNR by several dB." This is characteristic of near-field QRN/QRM. Field strength from nearby coupling can drop at fourth, sixth or even higher pow…
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As Martin has suggested, much of the coupling to an HF antenna system from VDSL, BPL or DOCSIS uplink tends to be by way of common mode injected current rather than radiated, either near-field or far-field, means. Achieving high symmetry with atten…
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Don't confuse lower levels with lower SNR, which can sometimes happen. A properly operating loop should have ultimate performance very similar to a similar sized dipole probe, at least up through mid HF, modulo antenna pattern in az&el which ca…
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jks, That would explain it. I really couldn't tell the model from the picture if it wasn't the same thing. But it is sure impressive how sub-milliwatts ERP do at LF. I transmitted a bit on 475 kHz with no more than 500 mW ERP, probably somewhat les…
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@smg Not to be too picky and it probably doesn't matter since it is all working usefully for you but... From your schematic do you believe that an air core coil of 15 turns x 60mm x 10mm is 1700 uH ??? I doubt that it is even 1700 nH. But I can…
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Really? http://192.168.10.89:8075/?mute&keys=yyys seems to work normally for me on v 1.701
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One absolutely can. Common mode current (not differential between pairs say) can be the most common cause of degraded noise floor. Current coming down the LAN (or PS), common to all conductors, flows into the 'ground' plane of the Kiwi (PS lines…
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https://forum.kiwisdr.com/index.php?p=/discussion/3520/interference-a-galvanic-isolator I suspect you are largely seeing common mode noise on the coax transmission line. While the loop antenna might have good enough CM===> differential isolatio…
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Pretty good that the PE4312 survived (if it did), enough to cook inductors.
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multi-page pdf, what will they think of next😀 How does one generate that, I've clearly been in KiCad too long and am out of touch with other tools! But the fact that of series L's, one burns up while the other survives it gets really interesting th…
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Wow. I doubt a pulse. Not enough energy to do this and not a lot of other damage as well. Maybe high power RF directly injected though. High as on the order of watts not milliwatts and for long enough to cause the heating/burning you see. Almost …
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I haven't checked for whistlers but I did go back and found that Alpha was Q5 in CWN on the 6m SA system here at the house: https://forum.kiwisdr.com/uploads/139/RPHQD5VZFGMR.png This at 1430 UTC from Northern Colorado and pretty far from any water…
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A couple of addenda: Solar controller power seems not to be a big deal as it only requires energy during periods of charging when there is a lot to be had. Our experience with snow at 7500' elevation in the Colorado Rocky Mountains is that while it…
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If I remember right, my remote+active_antenna+uwv_link is around 12W total with kiwi a bit less than half of it. Lots of places I think total storage can become the biggest deal but depends on days of sun/year etc.
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I didn't actually listen for it with CWN but you are probably right that I wouldn't hear it. This is from the very broadband Single Antenna system http://www.sonic.net/~n6gn/OSHW/BB/SA/SingleAntennaSystem.html only 15m from the house and neighbors…
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I remembered to look this AM from the house here in Colorado. I know nothing about Alpha. Is this it? https://forum.kiwisdr.com/uploads/654/7JQGRDZGPS1X.png