Construction of Kiwi 1

This is an unusual question I suspect only JKS can answer but in the interest of not adding to his mountain of work, I'll ask here. In a moment of carelessness, I managed to tear the SMA antenna connector off of both of my Kiwi 1's. One has a big sensitivity issue and one has a smaller issue. My question is this : Is the antenna signal delivered to the receiver via foil traces or by wires ? As I have tried to understand how tearing off the SMA connector could have affected the remaining terminal strip input, I looked closer at the broken SMA jack--it has wires attached. Are these wires how the signal gets to the receiver input ? If so, I can see how the signal loss is so high now and how shorting the input doesn't drop the steady S9 noise. Assuming that is how it gets to the actual input, is there a way to get a signal to the actual input or have I damaged my babies beyond repair ?


  • edited February 9

    Strange. Never seen such wires. Looks like something provisional.

    As you can see here, the input signal normally goes via nothing else but a copper foil trace into the shielded box.

    I would try to resolder the two GND pins of the connector first in order to fix it electrically and mechanically in its original position. As the solder pads may be lost, I would try to scrape off the solder resist from the surrounding ground area to be able to solder there. If the signal conductor track is torn off, I would try to replace it with a thin wire (which should exactly follow the old course).

    It's fiddly and requires some skill, but I think it's possible.

    If then tests confirm that it is working properly again, I would additionally stabilize the connector by applying some two-component glue.

    Alternatively, the terminal block could be used to connect the antenna (assuming it is still properly connected).

    Good luck!

  • Are those really wires and not flat PCB traces that have been pulled off the board? Your photo is a little blurry so it's hard for me to tell. Also, I don't understand why the one ground lug of the SMA has a wire/trace. It normally only attaches to a PCB ground pad as @dl7awl's photo shows.

    Can you post a photo of your board(s) around the connector area?

    I'm also really confused by the screenshot in the 11th post of the "Sensitivity below 700 kHz" thread. That screenshot shows an audio signal with an S-meter reading of -50 dBm (~S9+20), but the waterfall in the corresponding passband is less than -110 dBm. A 60 dB difference!

    I know you said you set the admin S-meter calibration to 0 dB (it's typically around -13 dB or so). But what is the waterfall calibration factor set to? Is it around -13 dB or something much larger that would explain the 60 dB difference?

    The other possibility is that if the characteristic of the noise doesn't integrate well it may produce an abnormally low waterfall reading, even though the S-meter is high. All of that waterfall stuff looks like switch mode power supply noise to me.

  • I get Status 400 fails when trying to attach a photo now... The meter does show S9+20 and the noise floor around -110. Waterfall and meter are both at -13. I believe this started after the SMA connector was pulled off. Putting a short clip lead across the input terminal does not change the S meter but it does raise the noise level slightly above 10mhz.

  • If your photo file is too large (over 1 or 2 MB) you'll get the HTML 400 or some other upload error.

    That's just weird that there's such a discrepancy between the two. I can't imagine how that could happen.

  • I learned more today. When I put my portable SDR on the antenna, I get superb quiet MW. I tried putting a T on the antenna and when I attached the questionable Kiwi and SDR together, the portable SDR got an S9+ hiss across the band. The Kiwi is outputting the hiss that shows on its own S Meter.

  • I thought you ripped the connectors off. What's the rest of the story here?

  • I did....I have RG174 to the terminals. One outputs noise and one works normally. While I cannot explain my original photo, let's discard it as I see no way that it could have come from the Kiwi in that form. Likewise, I recall nothing else that would have produced such a photo so I'll write it off to a senior moment. Meanwhile, one Kiwi is great and one outputs lots of noise on the antenna terminals. That noise was leading me to think both Kiwis were bad. That has now been disproven. Is there any repair avenue for the one with noise in it and an S9+ reading with a short across the antenna terminals ?

  • Okay, I didn't know you had made direct connections.

    I have sent you an email about what our next step should be.

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