KiwiSDR 2 production status

edited April 16 in KiwiSDR Discussion

[please see: latest production status info]

I received 5 prototypes three days ago (Oct 7) built by MacroFab. They work fine. I'm in the middle of characterizing them. The photo below lists most of the new hardware features (click for larger).

Some of the prototypes will be sent to beta testers who have exceptional reception and can split an RX antenna between a Kiwi-1 and Kiwi-2 so we can do some A/B comparisons. We should also have samples of the new enclosure soon.



  • RF attenuator in action. Signal generator set to -60 dBm. Attenuator set left to right: 0, -10, -20, -30 dBm as generator frequency stepped +1 kHz. Slight glitch in left waterfall trace is where attn was changed from -20 to -30 dBm before gen frequency changed from 10002 to 10003 kHz. Click image for larger.

  • edited October 2023

    Wonderful! Are you looking for beta testers? I would be happy to volunteer my site and time. I have a very low noise set up and the needed antenna port capacity.

    Carmine K1VL

  • Awesome!

    That attenuator will be greatly welcomed in my environment. I'm about 4 miles (~6.44 km) away from a 50 kW AM station on 1500, about 3 miles (~4.83 km) from a 5 kW AM (daytimer, thank God) on 770, and about 7 miles (~11.26 km) from a 50 kW (500 watts at night, also thank God) station on 900. I need to keep my attenuation adjusted enough to avoid having he Kiwi overloaded during the day when 770 is on and 900 is on day power. The attenuator also needs fine adjusting several times a year when the seasons change. Would be nice to be able to make those fine adjustments and perhaps adjustments between day and night right from the Kiwi.

    If I ever get around to putting my loop on a rotor that I can control remotely, that attenuator adjustment will be great for when the loop is turned.

    I have planned on adapting the antenna switch extension to be used with switching a step attenuator, but have yet to get around to it.

    Will this new enclosure work with the original Kiwi and will it be available separately? I know someone who bought an original Kiwi right before they were sold out and never managed to get an aluminum enclosure for it.

  • jksjks
    edited October 2023

    Some VLF/LF measurements. -90 dBm signal from an hp 8657D. Stepped from 40 to 10 kHz. Click images for larger.

    • KiwiSDR 1, unbalanced input, for reference.
    • KiwiSDR 2, balanced input, MCL T1-1 transformer (current design).
    • KiwiSDR 2, balanced input, MCL T6-1 transformer (for comparison).

    What conclusions can we draw? Well, if you want identical VLF response to KiwiSDR 1, replace the T1-1 with a T1-6. But note the greater amount of junk that seems to come through. This is probably greater common mode noise due to the higher inter-winding capacitance of the T1-6 as Glenn has warned us about.

    Don't be put off by the seemingly higher noise floor of the KiwiSDR 2. This is due to the extremely high local noise environment at my QTH that is more readily picked up by the balanced input configuration. This needs to be re-evaluated later at a quieter beta test site.

  • Thank you for sharing the measurements.

    Maybe it would be also interesting if you could do comparisons of the sensitivity across the frequencies.

    For example feeding a -120 dBm signal to the antenna input and measuring the audio SNR.

  • "I need to keep my attenuation adjusted enough to avoid having he Kiwi overloaded during the day when 770 is on and 900 is on day power."

    Have you tried adding some external notch filters or an equalisation network ?



  • Awesomeee!! So Excitingg!!

  • edited October 2023

    I do have a multicoupler on my four current KiwiSDR v1 receivers. I do have two more ports on it so I am able to do the A/B test. I run a 80-6m OCF dipole at 65 ft and have a decent location to be able to produce some meaningful results. Please let me know if that is suitable for a beta test site.


  • It looks so good that I already know what I will buy soon... I'm waiting for availability

  • Martin,

    I thought about implementing notch filters, especially for 1500, but I use the Kiwi mostly for MW/AM dxing, so I don't want to knock down parts of that band if I don't have to. Especially after sunset when 770 is off and 900 is on night power. I did have a step attenuator set up with a relay on a timer for a short while that was switching between a day setting and a night setting. Right now I just have everything in a fixed position.

    The built in RF attenuator would be good for those fine adjustments that are needed every so often.

  • a simple MW notch filter for one station will do little to impact the rest of the band.

  • If this station cause an overvolrage of ADC, then a notch filter will help. But it will be difficult to build such a narrow filter.

  • look at the MWBC on I have 3 notch filters on there on 1280, 950, 1370.... not much impact on the rest of the band. It will be full after sunset here in 4 hours

  • I'll have to revisit making a few notch filters, at least one for 1500 sometime. Not too long ago, I had another local DXer ask if I could construct a notch filter for 830 since he lives almost on top of 50kW 830 WCCO.

  • Just an update. Lots going on as you can imagine.

    • We are working with the beta test sites to understand some issues.
    • The online store is just about ready.
    • The software is getting there. The KiwiSDR 2 will ship with Debian 11.8 installed.
    • The NZ-based manufacturer has given us a final quote.

    Here are some photos of a prototype version of the case. The SMA connectors are reversed from Kiwi-1 because the Kiwi/BBG board stack is mounted "upside down" internally to make access to the SD card slot easier.

  • Somehow I've missed the physical dimensions of the KiwiSDR2 case some where along the line.

    Could they be repeated please?

    Also, thank you John and the Beta testers for their very appreciated efforts.

    Zeak, K6RRP

  • 120 mm long, and about 75 mm wide and 55 mm tall. This is without considering clearance for the connectors and the feet (another 8 mm).

  • Looks great John! It's encouraging to see how far this has progressed.

  • That's good news John and I like the design of the case, will the completed KiwiSDR2 ship from NZ? I ask since I'm located in New Zealand!!

  • will the completed KiwiSDR2 ship from NZ?

    That's the plan.

  • I'm really looking forward to being able to get one...

  • Looking forward to helping swamp the order store 😁

  • Any plan or date for production? 🙏

  • The third (and hopefully final) prototype version went out for fabrication last Monday (20 Nov). Being built by the manufacturer in NZ we have chosen to work with (the prior two prototypes were manufactured elsewhere).

    We need to be certain they can produce the exact production board without any problems before we place a volume order.

    So the online store will very likely open in December. Then my guess is a first batch will be available to ship late January to early February. NZ takes this holiday period seriously as it's the middle of summer here. So everyone (except me, lol) takes at least two or three weeks off.

  • Great news John, yes indeed I'll be off for two weeks during that period but likely chomping at the bit for the SDR. Cost?

  • Cost will be revealed when the store opens.

  • i Am interested. iT would be interested in 1, assuming budget approval from Mrs. DU9GT.

    George DU9GT

    Mindenao Philippines

  • This is awesome news. There doesn't appear to be a cooling fan in this design is that correct?

  • Correct.

  • "There doesn't appear to be a cooling fan in this design"

    Christmas has arrived early :-)

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