Re: Your NanoVNA version - good clone, semi-bad clone comparison
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I actually question whether or not the ¡°spike¡± is ¡°real¡±. And I further question whether it actually affects operation.
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There is a discontinuity at 300 MHz in the NanoVNA. The Stimulus is operating at the fundamental frequency of the Si5351 up to and including 300.000 MHz. Beginning at 300.001 MHz it operates on the third harmonic. So, at 300 MHz the Si5351 is producing 300 MHz¡.. at 300.001 it drops back to 100.000333 for the fundamental and the output is boosted by about 6 dB. When ranges are selected that include passing through 300 MHz the detected level at the transition changes by about 2 dB from the fundamental to the harmonic. I suspect that the spike comes and goes depending upon where the bin boundaries hit. I do not see the spike on my ¡°worse¡± unit but I am wondering what effect others are seeing on measurements made with the spike visible. WA8TOD At 299 MHz the NanoVNA is operating on the fundamental frequency of the Si5351. At 300
On Aug 25, 2019, at 3:47 PM, John Herleman <jherleman@...> wrote: Would it be possible to tell us - in layman's terms - how the spike at 300 MHZ can be corrected through software? |
Warren Allgyer