G8JNJ

Does this PSU seem adequate for two KiwiSDR's?

G8JNJ

May 2024

Everything is inside the box as shown by the dotted line.

Does this PSU seem adequate for two KiwiSDR's?

G8JNJ

May 2024

Philippe's comments are valid, but more related to Linear convertors / regulators.

This is what I did, but it is for a switching DC-DC convertor running at around 1MHz.

The capacitors were… (more)

Protection for RF High Power -

G8JNJ

September 2019

Some additional notes on LZ1AQ's pages

http://active-antenna.eu/application-notes/receiver-front-end-protection/

Regards,

Martin - G8JNJ

AGC Again [fixed in v1.441]

G8JNJ

February 2020

I should have added.

I think the term AGC threshold may be misleading. I'd expect that if you reduced the AGC threshold level down to say -130dB, it would be operating all the time, but actually the… (more)

AGC Again [fixed in v1.441]

G8JNJ

February 2020

Hi John,

I know we have discussed AGC settings and possibly implementing a bandwidth defined threshold in previous threads.

However I've just had to clear the cookies in my browser, and I notice that… (more)

rx.linkfanel.net receiver map moving to Leaflet

G8JNJ

February 2020

Hi Pierre & John,

Thanks for doing this, it's much appreciated.

I find the S/N map and rating list extremely useful, especially when trying to optimise my own KiWi's and also when trying to find… (more) KiWi's that are suitable for TDoA purposes. In fact it would be really useful if the TDoA Kiwi selection map could somehow indicate the S/N ratings of each in order to make the selection process quicker by ruling out KiWi's with really bad (unusable) S/N values.

I'm not sure how frequently the S/N values on http://rx.linkfanel.net/snr.html are updated, but maybe an 'average' and 'recent' display would be worthwhile additions ?

I must admit I'm biased about this as I believe that across the whole 0 - 32MHz spectrum, my KiWi http://southwest.ddns.net:8073/ is probably in the top 3 worldwide, although it's currently sitting at number 23 on the list with a S/N of 31.72 dB.

However when I have actually examined the spectrum display or performed an 'auto scale' test with the spectrum fully zoomed out I get better results (currently auto scaled as -22 to -114dB) than other KiWi's that are higher up on the list.

Its main competitors (by manual examination of the spectrum display of each) are http://nsk.proxy.kiwisdr.com:8073/ with a listed value of 40.35 dB (currently auto scaled as -17 to -115dB) and http://kphsdr.com:8073/ with a listed value of 32.79 dB (currently auto scaled as -35 to -118dB). All the rest I have currently tried in the top 20 on the list are worse performers, but it does depend to a certain extent on local time at the KiWi and propagation conditions.

Obviously the derived S/N values are not that accurate, as the percentile of power levels across the whole spectrum (signal), and the median power level (noise) depend upon the distribution of signals across the spectrum, how they are filtered and what unwanted noise is present that may seem like a valid signal. However despite these limitations, the S/N map is still the best way I've found to quickly sort out the really bad performers.

It's a pity that the http://sibamanna.duckdns.org/sdr_map.html map is no longer functioning, as that (at my suggestion) was modified to split the frequency range into several different blocks of spectrum, and gave average and current values for each, which provided a better overview of the likely performance, especially if you were interested in a specific frequency range.

I'm not sure how you can actually improve the S/N calculation without a very large amount of effort, but splitting it into bands and taking measurements at the same local time for each KiWi, may help improve the resolution.

Regards,

Martin - G8JNJ (less)

Adding Kiwi to my website

G8JNJ

February 2020

>
>I'm curious why you chose the RPA-1 preamp instead of the LZ1AQ for this antenna?
>

Hi Ron,

The RPA-1 has a 50 Ohm input impedance, so it was easier to match to 450 Ohms, plus the IMD… (more)

Adding Kiwi to my website

G8JNJ

February 2020

Hi All,

Details of my 'Loop on the ground' (or technically just above it) can be found on this webpage.

https://www.g8jnj.net/loop-on-the-ground

Treat the page as a preview as it's more of a working… (more)

Adding Kiwi to my website

G8JNJ

February 2020

Hi All,

Details of my 'Loop on the ground' (or technically just above it) can be found on this webpage.

https://www.g8jnj.net/loop-on-the-ground

Treat the page as a preview as it's more of a working… (more)

RSDN-20 beacons reactivated on 11.9, 12.65 & 14.9KHz

G8JNJ

January 2020

Hi All,

The Russian RSDN-20 beacons on 11.9, 12.65 & 14.9KHz are active once again after quite a long absence.

They must have found some more coins for the electricity meter down the back of their… (more)

Howdy, Stranger!

G8JNJ

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Reactions

Does this PSU seem adequate for two KiwiSDR's?

Does this PSU seem adequate for two KiwiSDR's?

Protection for RF High Power -

AGC Again [fixed in v1.441]

AGC Again [fixed in v1.441]

rx.linkfanel.net receiver map moving to Leaflet

Adding Kiwi to my website

Adding Kiwi to my website

Adding Kiwi to my website

RSDN-20 beacons reactivated on 11.9, 12.65 & 14.9KHz