n6gn
About
- Username
- n6gn
- Joined
- Visits
- 5,425
- Last Active
- Roles
- Member
- Points
- 31
Comments
-
FWIW, I had very similar symptoms when Comcast/Xfinity (US cable ISP) changed to a new on-line administration tool for my router. They 'kindly' added something that must be akin to an iptables entry at their gateway which flagged all the kiwi traff…
-
Rob is the expert but I saw symptoms that weren't too different when my RPI ran out of file system space because the tempfs hit its cap. Maybe clean it out and start over.
-
Ulli Interesting observations, thanks for posting. I'd add from my experience that in attempting to measure galactic noise at ~20 MHz , as the University of New Mexico reported, that horizontal polarization of a dipole is down at > 6 dB from ver…
-
Only slightly related to the BW issue, though Shannon says things stop improving very much after a while, once inter-symbol interference pretty much goes away, I guess. I'm really intrigued by the spectral plots of DRM. Having a bandwidth filled fai…
-
Ulli writes : "Any pre-amp made for short monopoles with high impedance will just amplify the common-mode current as well... " Which is why I build active short dipoles instead of monopoles and use them with very high CM rejection, high i…
-
Ulli, Another advantage of the preamp, beyond simply improving the kiwi's noise floor, is that it pushes common-mode ingress occurring after the preamp further down by the amount of the gain. A disadvantage is that it may push the kiwi closer to OV.…
-
If WD is started with verbosity level 1 then simply typing cat ME*/*/posting.log will show a comparison among all merged receivers or something like cat ME*/20/posting.log to show recent results from a single band (20 meters in this case) Jim's met…
-
There's also a tool/method to compare the posts (SNR ) from each of Merged receivers. This is interesting because it gives insight into angle of arrival, noise and other aspects of each receiving system. Unfortunately I've forgotten how to invoke i…
-
2W sounds like a good estimate. I think that this might be workable, especially on a 28V system. One 28V panel, two 12V deep cycle/marine batteries, a linear battery charge controller (may have to build it and add an Arduino/PIC to get good perfo…
-
Interesting. Can you measure the power consumption of the switch alone. Their web site says 5W but I'm wondering if that is typical. For a remote (solar) site power can sometimes be a secondary issue.
-
I think I might try a battery located at the preamp, powering the preamp, in order to determine whether they are coming in before or after it. Then work on the problem that the results indicate. One possibility is that they are entering via common…
-
Bob, Yes, you've just described the essence of recent endeavors. It appears that a 1-2m antenna (I've been using a 2m dipole) and available components can get one to the propagated noise floor up to somewhere around 10-12 MHz. I think it doesn't…
-
Bob, Thanks for posting. I find this kind of detail helpful. Your four measurements seem just about right. If I understand things correctly, your spectrum display has bins 30MHz/1024 wide so KTB should correspond to a display of about -130 dBm. S…
-
http://forum.kiwisdr.com/discussion/1683/combining-diplexing-antennas-to-single-kiwi#latest I'm confused by this thread. Are there two with the same title? I guess I don't know what "comments" are...
-
NEC2 file from 4NEC2 but the deck should run on most of the flavors
-
If redqueenuy.ddns.net:8073 is the kiwi in question, it looks me like a family of 20 kHz lines, probably BJT at that frequency, SMPS lines with 2nd harmonics lines of 20 kHz visible but only at the low end of the kiwi. It's remarkably close to 20 …
-
CM 4 leaf biconical with double wire conductor for upper HF CE SY len=3.0 'cone element length SY angle=30 'with respect to z-axis SY xdim=len*sin(angle) 'major yardarm SY zdim=len*cos(angle) SY feed=0.05 SY feed_width=0.0 'minor yardarm SY angle2=2…
-
@w1euj It's a four leaf subset of a biconical as shown near the beginning of this thread. I've not written up a construction article for it. Perhaps after we've put it at the remote site, maybe in conjunction with an existing active dipole to cover…
-
The problem with comparing with a small antenna is that the real part of the radiation resistance is swamped by the antenna material, matching loss and on receive, preamp noise and ingress, thus efficiency isn't as easily deduced. The (small) Rr is…
-
Too bad. Even the results from a nanoVNA measurement (which are generally pretty good) would allow a pretty good estimate of broad band efficiency and give an idea over what range in the spectrum it might be sufficient to get down to the ITU noise f…
-
His comment "When I listen those signals in 160m in AM, sounds like a MW stations pile up (IMD). When I turn the antenna amp off this is what happens:" leads me to think it is not a family of lines from a switcher... Worth studying thi…
-
Can you provide S-parameters for LF-through HF for that antenna as mounted? I have a hard time believing that it 'works well' at the low end since it is too small to have good efficiency against real world materials/grounds. It is very likely just…
-
N0EMP built a prototype of the modified biconical that I suggested and previously modeled with NEC2. We measured it in situ with the bottom less than 1m above earth and I then built a simple matching network intended to match it over 12-30 MHz. He…
-
I haven't analyzed the IMD of your cascode MOSFET and follower but from your screen shots I think it is clear that you have almost no common mode rejection at upper HF. The transformer you are using probably has no more than a very few dB inter-win…
-
The cluster around 25 MHz looks like it may be the 60 kHz LAN family and is an indication of insufficient common mode rejection, not surprising for an unbalanced antenna and coax. If this is conversion from common mode current on the coax, possibl…
-
Next time you plot it, use the spectrum display instead of the waterfall so that relative levels can be discerned.
-
I agree that the waveform is interesting, not least so when viewed in the kiwi waterfall as you've shown. Looking at it, one can almost "hear" the results of frequency selective fading/multipath that are so often observed on HF broadcast …
-
I don't think it is possible with the kiwiSDR without redesigning the whole receiver, is it? The stock kiwiSDR has 12 kHz information bandwidth, the 3 rx version can do 20 kHz in each channel. If you want true wideband FM, you need an information …
-
Yes. I've done clean installs on an RPI3 but not with recent WD code.
-
I noticed on Jim's BB/AI that it took a longer time for changes in zoom to catch up in the waterfall - as suggested by Stu's image.