n6gn
About
- Username
- n6gn
- Joined
- Visits
- 5,359
- Last Active
- Roles
- Member
- Points
- 27
Comments
-
In the past, I've managed to notch WWVB at 60 kHz and only 20 km distant, with a simple series LC filter at the 50 ohm input. I can't easily find a schematic of what I used but from memory I think it was a high permeability toroidal core with whatev…
-
Actually eBay FM/TV cores with only 2 or 3 turns on each winding DO have enough permeability to get down to the low end of HF, though as you say not MF and LF as well. Asking any inductor for three to four decades of BW is a very tall order since…
-
You can measure 1 pf with a nanoVNA or similar VNA in 2-port mode. Connect the grounds at the end of the test cables and hook the primary/secondary as a two port device on the centers. This is just like measuring a small capacitor. If you see some…
-
I don't know about the ADT1-1+ but I do know that the T1-6T+, spec'd to go lower in frequency is NOT a good idea. Rather than being a simple flux coupled transformer with low inter-turn capacitance it appears to be a transmission line type, even t…
-
Just had a minor event. Here's the noise at N6GN/K2 https://forum.kiwisdr.com/uploads/642/IEYIV1JQTADN.png It might have to be a pretty short time period to differentiate antenna fault from absorption increase!
-
With an increasingly active sun, as we are now seeing, I wonder if it might be difficult to use S, N or SNR to determine antenna broken-ness. On a good receive system achieving ITU propagated noise floor, SIDs from X-ray emission induced absorption…
-
see edited file previously posted for .brd file to have fab'd.
-
Just 1:1 on small PCB, SMA male to Kiwi Completely isolated from SMA female to antenna feed line. This leaves only about 1 pF of common mode coupling between Kiwi and antenna line. https://forum.kiwisdr.com/uploads/075/BFPL5TMWNGYI.png top side of …
-
Not an answer to your questions but previous examination with an SA shows a lot 1575 +-MHz lines emanating from the SMA end of an enclosed Kiwi. I found, as you did, that moving the puck perhaps 5m away made a gread deal of improvement. This even …
-
At 100% modulation instantaneous power is very likely pushing the Kiwi into OV, if your calibrations are correct. This happens at around -15 dBm. An easy test is to insert 6 dB of external attenuation and see if the artifacts go away.. I suspect tha…
-
The inexpensive ~960 kHz buck converter mentioned elsewhere on the forum will likely get you low end performance uncompromised. I think they cost about US$1 each...
-
Sorry to say all this yet again... As one who successfully uses SMPS on multiple Kiwi's and has systems with noise floor below propagated noise levels at least through mid-HF, I would suggest that ferrites are almost never the solution. The prob…
-
Yes. Go to wsprdaemon.org and look it over. A greenfield tutorial is at https://github.com/rrobinett/wsprdaemon and in general the problem of getting the most performance from a KiwiSDR is discussed at length, in its various aspects at https://gr…
-
PS noise is generally due to conducted, common mode noise current. The Kiwi is pretty impervious to differential noise so more C's or series L's don't usually help. These small, cheap supplies have a high switching frequency and because they are …
-
While that might work for two Kiwis, especially if they start at different times, some of us have turned to an inexpensive alternative. While these run from DC rather than mains AC and one has to provide that separately, and while they are SMPS so d…
-
To the best of my knowledge, WF bins are each 1/1024 of the total span. I think the levels reported by the comms side more or less match what one 'reads' visually from the WF display. Be careful not to read to much into WF levels/bins though. It is …
-
One of the great benefits of an SDR like the Kiwi which has a controlled and known gain path from the input connection to the detector is that it is, in theory, possible to make absolute signal and noise measurements. Furthermore if the transfer fun…
-
IMO, this is an important problem. wsprdaemon calculates noise using two different methods, one looks at the (expected) quiet period at the end of the 110 second WSPR frame and the other looks at a value calculated over the entire frame. Not surpris…
-
Thanks jks ! I just tried it using an offset of 527987.5 and after reload at the browser got a display and calibration of an over-the-air 548.309440559 HDTV carrier (rubidium referenced, I think) to read within the limits of the (rather dirty) no…
-
In looking at it, do you see any way to remotely set the "frequency scale offset" mode, either by the URL or otherwise?
-
OK, that's better than nothing but not really quite optimum since a given Kiwi may be used on both HF and and a VHF/UHF converter where HF is 'perfect' with no residual error but a converter might have some. The ADC adjustment affects both so each c…
-
But still only to the nearest kHz, isn't it?
-
@studentkra that's another good reason that a software correction of both WF and Dial would be better than a hardware one. The Si5351 can be pretty clean if/when small, even integers are used in the frequency generation plan. But if small offsets …
-
This is an area that interests me in that I would like to see an API that will allow changing the scale programmatically to match user tuning of the 0-2 GHz Frequency Extender I have designed, built and which is now operational. I'd like this for b…
-
At the urging of Tom, WA2TP, I created a GPSDistribution PCB which isolates both the center and shield of the coaxes of up to 8 Kiwi's from one another at all but GPS frequencies: https://forum.kiwisdr.com/uploads/629/SSR5LF5RV33G.png It has an addi…
-
@jks would be the one to comment on diagnostics but do be aware that there is significant radiation from the SMA connectors/end of a KiwiSDR that can pretty easily QRM the rx. If you haven't already, move the antenna at least 15' away from the SDR a…
-
That's my understanding. The internal code has a value it calls "clock frequency" and if that matches actual external input then there is no error. When I first tried an external Bodnar reference on a KiwiSDR a few years ago, there was a …
-
If it isn't exactly 66.660000 MHz I think there will be frequency error. Isn't having a correct clock the whole point?
-
Photos of the Antenna Switch https://forum.kiwisdr.com/uploads/Uploader/5f/492f44efb5a272d715c5219da67b44.pdfare fuzzy but do show one of my Kiwis with an attached Bodnar coax: https://forum.kiwisdr.com/uploads/713/E4CO9VTEGJG1.png https://forum.k…
-
Have you set the callsign/grid under admin:extensions:wspr?