n6gn
About
- Username
- n6gn
- Joined
- Visits
- 4,516
- Last Active
- Roles
- Member
- Points
- 18
Comments
-
Try a MiniCircuits T1-1 located right at the Kiwi. It has about 1 pf interwinding capacitance and a low end that will almost make it to 100 kHz. The dipole (what size?) no doubt has a great deal of mismatch loss at LF but ITU noise floor rises fas…
-
A careful assessment of the spectral purity from the Bodnar mini and original GPSDOs while tuning in the 66.66 MHz region would require quite a lot of effort. High resolution frequency generally means larger integers and the risk of boundary spurs …
-
Wow, can't help you there while there are higher current versions avaialbe I haven't found one that switches at higher rates and also has small area so as to minimize unwanted coupling. I think with some care you might be able to parallel two of th…
-
These https://smile.amazon.com/gp/product/B01MQGMOKI/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 have shown themselves to work pretty well. They switch at just below 1 MHz and have quite small area so don't generate a lot of field. Some of…
-
Thanks for measuring. That's a lot more power than BBG or even, I think, than the BBAI. Perhaps fine where there is sufficient power budget but not clear to me that it is a good choice for a remote solar power site.
-
The System Reference manual says "A 5V ≥ 3A supply is mandatory" has anyone measured the actual peak and average current or power under Kiwi-like operating conditions? I don't see it described in the documentation.
-
I think I might take exception to the ability of a native Kiwi/GPS to do a good job on 20m and above on modes longer than 120 seconds. Particularly for FST4W's -300 and longer modes, short term stability of the Kiwi's clock seems to incur enough sp…
-
Don't immediately fault the Kiwi HW because the reported SNRs are different. At low levels SNR numbers are suspect (ref K1JT) and it is likely that the algorithm has changed between the extension's decoder and WSJT-X. If the noise floor is establis…
-
@jks Now that you've already downloaded the monthly tome I thought I'd mention that wspr.rocks also (mostly) reports version, can go back to the beginning of time (well, you know what I mean) and is blazingly fast. Here's a search of unique calls …
-
See my previous post. FT50-61 and about .012 uF is one solution. Make the C from parallel .01 uF and a ~.002 uF trimmer. You can probably see where the center of the notch is by loking at noise floor. Tweak the .002 uF as necessary. Make it from mul…
-
"nearly 60 dB over so probably want at least 20 dB reduction ?" No. You really only need about 3 dB to get out of OV. This is an SDR not an analog receiver, level doesn't matter much until you run over the top of the ADC and then it tota…
-
Although a complex filter like this can no doubt be made to work just fine, it reallyl is over-kill for your problem. All you really need to make the Kiwi happy in your situation is a few dB of attenuatiom right at 272 kHz. For this, the simple seri…
-
I think you want a smaller core with lower permeability, maybe something like this (handy calculator here) http://toroids.info/FT50-61.php with about .012 uF. I don't think wire loss will dominate so small wire that lets you get 20 turns and prett…
-
There certainly was ! How quickly I forget... Apparently none of those previous suggestions were followed and the request "Any filter I could use to filter the LW band" doesn't include home constructed ones. oh well....
-
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…