Hi Jeroen, My comment was meant to double-check that it's not a PC-related SW issue of some specific sort. Take care, Klaus, DK3QN Am 04.12.2020 um 19:11 schrieb PF1JM via groups.io:

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Problem found - My 10MHz distribution box is based around LM7171 high speed opamps, and the 600kHz instability originated in there - and changed in frequency slightly with loading. I added a bit of ex

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Klaus, No, but I suppose that will work. Just as SDRconsole, FDM-SW2 gets its data from the RX port. Jeroen PF1JM

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Checked with FDM-SW2? Klaus, DK3QN Am 04.12.2020 um 16:30 schrieb PF1JM via groups.io:

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Hello group, Since a couple of days there is no audio in or out via the USB TX port of my FDM-DUO. Experenced this at first while it was connected to my raspberrypi, but on Win10 PC it’s the same... C

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RF sometimes takes some unexpected paths :-) I can speak from my own experience ;-) 73, Klaus, DK3QN Am 04.12.2020 um 14:25 schrieb Andy G4JNT:

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STOP PRESS !! Ignore the 670kHz spurious - it's my end I always run the Duo from an external 10MHz reference input. When I disconnect that and use the internal ref those wobbly 670Hz sidebands go away

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Just taken a look at the one spurii pair that SHOULDN'T be there, the two sidebands, approx -50dBc at +/- 673kHz This plot shows one of the spikes and varies in frequency over about 1kHz - appearing a

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I'll disconnect the USB ports and try SSB to see if the +-48 kHz stuff disappears Neil G4DBN

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I should have said that although the wideband plots 'look' very messy, there is nothing in there you would not expect from a DDS based source, using a sampled Numerically Controlled Oscillator clocked

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I spent a fruitful hour just now making some plots of the FDM-Duo, 0dBm output at frequencies of 29, 70 and 144MHz. Looking at both wideband and narrowband and very narrowband spectra. There's no sign

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Hi all, I forgot to thank David IW5BNL for his reply. Many thanks for all these measurements and ideas. The high frequency spurs should not be a problem, I use a LPF at output. Klaus I would be very i

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Hi Andy, And thanks very much for your comment. That will surely save my night sleep :-)) No bad dreams tonight :-)) Take care, Klaus, DK3QN Am 03.12.2020 um 20:03 schrieb Andy G4JNT:

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'735' is the second harmonic of the Tx sampling clock at 368.64MHz 1.47GHz the 4th harmonic. It looks as if they've used an elliptic filter on the Tx output and the peaks in the stopband are showing u

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(quote) The largest two are at 1.47 GHz and 735 MHz at -28 dBm. (unquote) Exactly Neil, that's what I saw today as well. Quite weird and I didn't have the time to think about that. So I didn't upload

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The results on SSB are definitely much worse than CW or TUNE. It will be interesting to compare if you have time to try USB and LSB modes. Of course there are other proiducts at 341, 401, 735 MHz, 1.4

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For completeness: here are the scans close-in of the carrier (with 20dB external attenuation): Klaus, DK3QN

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GE all, I did a quick scan today of my DUOs low level output (0 dBm output connector) on my SA. Test set-up: DUO in stand-alone config and powered by a 4S LiFePO4 pack. No other cables connected to th

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My thanks to all who replied.. I'll be trying the suggestions tomorrow.. Dave KK7SS

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Hi Andy et al, I will check my DUO (very early unit) tomorrow afternoon on my Siglent SA, when I have some leisure time. Klaus, DK3QN Am 02.12.2020 um 22:18 schrieb Andy G4JNT:

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