KiwiSDR 2



  • Okay, so we have a dual footprint for the antenna balun now:

  • edited August 2023

    Glad you could fit it there, thanks.

    I wonder if it would be useful to add a choke in series to the static drain resistors. Just to make sure there is really minimal common mode current. But 100k is probably enough.

  • I might have an idea about the Kiwisdr 2

    that you might increase the frequency range so that you can also hear the other bands such as from 30mhz to 1.3ghz

    73 Highspirit

  • That won't take place as it would be an almost completely other project.

    As Johns opening post indicates, KiwiSDR 2 is planned as a new edition of the previous one with only minimal and low-risk changes. No more, no less.

  • I don't think the chokes would contribute anything further.

    Stray capacitance between placement of the coax cable and case is likely to be a much more significant factor WRT common mode currents.

  • I'm getting lots of new forum registrations from people indicating they'd like to purchase a KiwiSDR 2.

    At some point I will conduct a proper poll to gauge interest. I have to know how many to build in the first manufacturing run. It's possible we might even do another Kickstarter or maybe a Crowd Supply offering. I would welcome any ideas about this.

  • New Kiwi? The best good news for me today! With the Kiwi I had the best SDR experience ever ... I got in contact with many users and would buy definitely a new Kiwi-V2 as a backup. It is so much fun to go anywhere and listen to the home receiver with my mobile phone or Laptop.

    The LF spectrum is important for me, too. Although some services are going to quit here soon in Europe, for example the Danish Brodcasting annd BBC Channel 4.

    Best wishes Michael

  • As I knew regarding one mini-handhe NXP-tef6686 radio project, the initiator still adopted crowdfunding to ensure a limited inventory and smooth distribution (in China). FYI.

  • No matter when or how much, I'm up for one.

  • Regarding the PE4312 step-attenuator low -frequency performance:

    As a former PSemi development engineer, I can tell you that there actually is a hint of the low-frequency performance on the first page of the datasheet, it's just not immediately obvious.

    "no external blocking capacitors are required if 0 VDC is present on the RF ports."

    This is confirming to me what I assumed, that the inputs and outputs are essentially DC coupled and that the 1 MHz lower limit is somewhat arbitrary.

    They certainly did some datasheet characterization down to 1 MHz and the Figures 14 and 15 show that step error was characterized down to 10 MHz. I'm fairly certain that they never tried to measure the part below 1 MHz, because that is simply not the area of focus. They don't want to indicate a low-frequency limit of DC as that brings in other complications, so 1 MHz is just a nice round number to use in the datasheet that won't "get them in trouble" with any customer.

    There won't be a series blocking capacitor directly in the RF path of the chip itself because, since they are specifying performance down to 1 MHz, any series capacitor would have to be quite large from an integrated circuit point of view. Anything more than ~1 pF (likely less for this product) will require far too much die area to be economically feasible. In addition, a series capacitor would represent an ESD risk. So there won't be standard single-pole roll off in performance below 1 MHz.

    I don't know exactly what the LF performance will look like but I'd say that there is a very good chance that it works well down to at least 100 KHz, probably lower.



  • Hi Steven,


    I saw that the input power de-rating curve falls quite sharply on frequencies lower than 15MHz, and is not projected any lower than 2MHz.

    This made me wonder if the IMD performance would also be degraded on these lower frequencies.

    However Real life / Bench testing should confirm that there isn't likely to be a problem.



  • Hi Steven,

    Good info -- thank you very much.

  • Such great news that this is even a possibility.🙏 I was late to the kiwiSDR party and managed to score one only literally weeks before they seemed to disappear from the marketplace. Needless to say I would certainly not let that happen with kiwiSDR2 and would be in the early queue.🤞🤞

  • Can someone who has had recent experience with JLCPCB's PCBA service, procuring non-LCSC available parts using their "pre-order, global parts sourcing" service, please email me at ?

    I'm finding the process to accomplish this very confusing.

    Thanks in advance.

  • Martin,

    I did not work on the PE4312 (and I left the company the same year that it was introduced, 2017) but their stuff has a lot of common characteristics due to IP reuse and they have evolved generally accepted good practices there. One thing they have had plenty of time and practice to get right is making switches and of course this step attenuator is essentially a series of switches around fixed attenuation blocks.

    I forget the exact reason why the power handling drops off like this at low frequency on basically all their products but I vaguely remember it perhaps having to do with longer conduction cycles as frequency decreases, current density concerns (a transistor of a particular style is specified to tolerate only a certain amount of current per area) and electromigration (which is mostly about metal interconnects). This seems more likely than pure transistor breakdown because BVdss should not change over frequency.

    In any case, putting the chip under stress close to maximum power handling is a very long way from a garden-variety IP3 measurement, which by definition has to take place below the compression point. I don't think the two are related here. Their IIP3 plot stops at ~10 MHz (due to measurement complications more than anything else) but I expect that as long as the insertion and return losses do not dramatically increase at LF (and I don't see evidence of that) then the IIP3 won't change much.


    Steven W6SPB

  • I'll happily back KiwiSDR 2's development! I really want to purchase one.

  • Hi Steven,

    Thanks for the detailed information regarding the device topology.

    That has answered a lot of the questions I had, and is more reassuring for use in this particular application.



  • Very interasset we will contact you and would like to join for distribution in Switzerland (neighboring German speaking EU area).

    73, Dani HB9HEH

  • Looking forward to buy one as I was too late for the first generation.

    focus here is VLF/LF (like several others as I noticed 🙂)

    73, Ulrich PA7EY

  • Great news. I consider the KiwiSDR network the greatest thing in ham radio in the last decades. I use it to compare my home built devices.

    Just wondering why a submission for an ARDC grant was not applied (AFAIK). Those people sit on a pile of money and some of their grants look "questionable", see for yourself.

    I would like to see a bigger and better network, and a reward for the people behind it, designer and operators.

    Sorry if this has already been pointed out.

    Alberto I4NZX

  • jksjks
    edited August 2023

    Re: ARDC: The last thing I need in my life is (more) politics, lol. Thank you for the suggestion however.

  • Glad to support with my purchase when you have it ready. Wspr skimming is my intended use of it. Hoping for better performance in a couple of areas compared to my Red Pitaya setup. (Frequency stability and sensitivity on upper HF bands)

    Thanks for your hard work on the project. I see the whole project as epitomizing the ideals of Amateur Radio both in the areas of advancing hardware development and promoting good will with the open network.

    Mike - KV4TT

  • Or the barrel connector on the BBAI-64, in my case, which works fine, and can be fed enough potential amps that I don't sweat underpowering anything.

    This is great news. I have toyed with many SDRs and will continue to experiment with others, but the Kiwi is my hands down favorite. The ELAD interface deserves mention as being nice too, but it is far more limited in what it can easily do. I was pretty unhappy with a future of being stuck with the available interfaces of some of the other options,

    I'm no electronics designer, but I would also be happy to test any early units if that was useful.

  • Great News John.

    Kiwi SDRs have provided a door for many to access 100s of KiwiSDR Radio RX from anywhere.

    Sincere thanks for staying with it and endeavouring to come back with more of a proven formula with subtle improvements. Having lost the Front Broadband Amp on a MK1 fully support the enhanced protection proposed.

    Great Job


    Murray McGovern


  • Oh this is the best news in quite a while. I am definitely down for the first run! My Kiwi is freaking awesome and I've just been dreading the possibility of losing it with no worthwhile alternatives..

  • Hello John, Dear all,

    That's very good news. KiwiSDR is a great system. As soon as available, I will buy you one or two new V2 cards for the Trémolat antenna. With pleasure.

    Best regards, Philippe

  • I'm certainly up for at least one Kiwi2.

    This is really good news. I like the idea of a buck/boost DC input. I'm not a big fan of the ubiquitous barrel connector either, but hard to beat I suppose when it comes to not eating up board real estate.

  • The DIN barrel connector is pretty popular across a number of devices. John, have you found issues? The only thing I have is that if you pick a PSU with USB, it's 5V a DIN barrel might be anything

  • Yep, and they are everywhere, but I find them fussy to build with appropriately sized conductors and the pre-made ones are usually of very poor quality with very little copper in them. I like the green rectangular connectors better, but I know they consume more board space. It's a "nice to have" rather than "must have", and I've made some robust DC cables with real wire cross section already.

    I'd be fine with participating in a kickstarter thing too, before I forget.

    The prospect of a Kiwi 2 is really exciting. There's so much software infrastructure already in place, it would be fantastic with a more contemporary SDR platform to run it on. Updating from the BB to a modern Pi would be a huge step up too, IMHO.

  • DIN barrels are available with "green" terminals too!

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