Re: Spurs/Harmonics fixes for v4 based on v5 board design?

Bill Cromwell <wrcromwell@...>

Hi Evan, Dave,

I looked at the 'specs' as shown on the Amazon page Dave referenced. It didn't include information that Evan has given. The big deal about a spectrum analyzer is a requirement to display very weak signals that live right next to very strong signals. Good shielding is also required. There is nothing in those specs I saw to give clues about those requirements for the measurements we want to make. Maybe the RF Explorer can do the harmonics as Evan says. Maybe others can report their results.

We can get at least some usable information from just about any 'spectrum analyzer' system including the RTL-SDR dongle and our computer sound cards. Evan an old fashioned 'wobbulator' But maybe not good enough for the kind of "measurements" we want to make here. It could be better than nothing at all. Or it could even be worse than nothing at all. Worst case is they can say "something is there". Determining just what and how much may be out of reach. Let's see what others have to say about that RF Explorer. I just ordered some 'toys' from Amazon and that RF Explorer caught my attention. I took a pass on that.


Bill KU8H

On 1/21/19 9:55 AM, Evan Hand wrote:
>From my personal experience the RF Explorer seems to be good at the
harmonics.  I have measured the 3rd harmonic at the same levels as reported by others (between 35 and 40 DB down), which gives me confidence on that front.  I have not been able to measure the reported spurs on bands above 20 meters.  Makes me question the usefulness for that measurement.
The minimum bandwidth setting is 112khz, which is broken into 112 segments so that each segment is 1khz wide.  That is then measuring only 112khz of the spectrum.  If you open the bandwidth to cover more, the resolution goes down.  So that for a 1.12mhz bandwidth, the resolution is 10khz, and so on.  What ever is displayed can only be divided into 112 discrete measurement intervals.  Based on that spec, it should work.  I just have not been able to see the spur.  More likely an error on the operators part.
Overall I am not disappointed with the device, it is 1/8 to 1/10 the cost of a Siglent or Rigol.  It is also portable (the main selling point) so that you can use it in the field.  However, If you are going to get really serious on RF measurements, then it may not be enough.
Above is my opinion/experience.  Yours may vary.
bark less - wag more

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