HB9TMC
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Comments
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Works, thank you!
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Does the kiwi boot if the GPSDO is connected but with its clock output disabled? It could be RFI to the BBG. You could try to reduce the signal level from the GPSDO. Or add a 50(?) Ohm load across J5 on the kiwi.
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@studentkra Yes there is harmonics from the SMPS radiated on VHF. They only start to show up above about 40 MHz. I think it is radiated from the kiwis antenna cable. I do receive them too on my 6m antenna very weak, which is about 10 meters away. I…
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If I understand studentkra's issue corretly, the problem is radiated interference from the kiwi to a different receiver? I can measure the SMPS harmonic at 65 MHz from the kiwi with a H-field probe about 5-6 meter along the antenna coax. But that s…
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It's probably a lot of work, but you could try to debug, using strace -p to see what kiwid does when you access the web interface.
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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.
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I got the resistor arrays replaced and everything is now as it should be. Also the noise floor without antenna connected, which was too low with the dysfunctional D3/D4.
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Yes, field strengths are high on VLF/LF, but most broadband antennas are either severely mismatched or have low gain in this frequency range. For example the noise floor on my 50m endfed wire antenna is just -150 dBm/Hz at 50 Ohm on the 136 kHz ham …
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I use every tenth of a dB in that frequency range, that's why I mention it. But agreed, CM rejection isn't as good, particularly on the higher frequencies. Here's a rough measurement of my FTB-6-1 https://forum.kiwisdr.com/uploads/886/76S2I9NPUX8U.p…
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ADT-1-6 has 0.08 dB at 50 kHz. I think it is better suited for the kiwi than the ADT-1-1 and it has the same footprint. I think there was ambiguity whether they are galvanically isolated, but mine are. (And from the datasheet they are as well)
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https://forum.kiwisdr.com/index.php?p=/discussion/comment/14238#Comment_14238 "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…
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Does anybody have insertion loss measurements for the ADT1-1+ at VLF/LF range (10-150 kHz), the specs in the datasheet are only for above 150 kHz and it seems to be increasing towards the lower end.
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Good to hear! Which input transformer do you use? According to the data sheet, the PE4312 has a lower frequency limit of 1 MHz. What are the implications for frequencies below 1 MHz? Maybe I read it over, but I can't find anything about it in the da…
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Maybe the logs give a clue why kiwid crashed /var/log/messages and the "dmesg" command.
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In that case, the coax shield was positive. If the bias-T's power supply has negative connected to mains earth, there could have been current running through the kiwis GND. I would check the voltages too. (Also since the AI-64 might draw more power …
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It's the resistor array. The resistors for D3/D4 are open. I don't know how i missed that before. And I don't know how that could happen. Considering the circumstrances, the FPGA input might be damaged as well. Its input resistance is not suspicious…
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The TVS diode shows >200 MOhm, I think it should be ok. Resistors are good and caps are not shorted. I probed the ADC output again and i noticed that two pins are not switching, D3 and D4 are both always low. Does this explain the behavior? https…
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Something seems to be off though. During the evening hours in the presence of strong signals I noticed a higher noise floor. Noise floor without cable attached: Good Kiwi: -119 dBm, fixed Kiwi: -124 dBm Noise floor with -20 dBm test signal on 28 MH…
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Yes, it was just the LTC22481 and the GPS is working. The preamp is ok. I didn't had a differential probe to properly measure the gain, but I measured about 10 dB gain to ground, so I thought it was good enough, and it turned out, it is ok. The ante…
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The ADC has been replaced and everything works again :)
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Although not all flares come with radio emissions, and not all radio emissions are due to flares. For example, solar jets often produce intense type III bursts, but they cause almost no x-ray emissions. Radio emissions are produced when a coronal ma…
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What's your antenna Martin? It's also interesting to compare the own plots with the e-callisto solar spectrometers: http://soleil.i4ds.ch/solarradio/callistoQuicklooks/
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That's a beautiful spectrum of type II and III emissions Martin. I see solar radio emissions too, but unfortunately i have a lot of PLC noise above 15 MHz, so it doesn't look as great as in your spectrogram. I'm actively following solar activity for…
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Yes, I would give the kiwi to a company which does repairs. But I think having a full diagnostic done by them would be too expensive. I measured the semi-high with the oscilloscope, there is no switching on any output. Resistors are good. So I will …
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The ADC is definitely broken, but out of curiosity I set it up again with a proper signal generator as external clock source. Sometimes I get a waterfall with -120 dBm, sometimes it's black, but tunable and it shows a -127 dBm level with overflow fl…
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The DC voltages and GPS clock are good. The only thing which is definitely not good is the input resistance of the ADC clock (30 Ohm). I think it is pulls the clock voltage to a level which is too low. Or the input is completely broken. Bypassing U4…
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Could it be that you chose the wrong subnet/netmask for the kiwi? Or that the PC is in a different subnet than the kiwi, respectively. You could access the kiwi through a usb network interface: http://kiwisdr.com/quickstart/#id-net-usb
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No, i've only used the external clock for diagnostics. I just wanted to ask for the options, before i put my hands on the U403/U406 because I'm not very experienced with SMD soldering and don't have the right tools currently here. Unsoldering: yes, …
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When the kiwi is powered off, i measure 30 Ohm from the XO output to ground, which seems to be low. On the good kiwi it is several 100 kOhm. With "external ADC clock off", I measure 670 mV on the input of U406 and 3 mV on it's output. U406…
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The oscillator appears to be running, on the output pin I measured 670 mV (1.39 V on a healthy kiwi). But it doesn't make it to the test point. I'll look into it again tomorrow, Anything particular that i could test on the ADC?