Tuesday, June 19, 2018

Comparing SDRPlay's spectrum analyzer function with calibrated HP8563A

With identical attenuators on each analyzer's input - and with the KX2 set for a 5-watt output, I re-ran the test comparing SDRplay's spectrum analyzer program with an HP 8563A. That program, intended for SDRplay' sline of receivers, can be downloaded here.

A previous comparison was made using the KX2's minimal output of 100 mW and with the rig being incorrectly keyed (misinterpretation of the XMIT/TUNE button) to produce a steady carrier.

The results below are an accurate portrayal of how each device responds to the KX2 on 3.5 MHz. The HP is calibrated annually and was last calibrated in Feb 2018 (four months ago) and it, of course, is displaying accurate results.

(For those interested, I also looked at the KX2's other bands and posted those plots here. Given the 10 MHz span of the SDRplay's Spectrum analyzer program, it is not possible to look at bands higher than 40 meters).
HP8563A spectrum analyzer, 80m: second harmonic is 52.63 dB below carrier

SDRplay's spec-an function, 80m: second harmonic is indicated (falsely) as being 41.9 dB below carrier


1 comment:

  1. Two readers have emailed me about the OVERLOAD (above, in red) indication on the RSPduo's software.

    Unfortunately, even though it shows Overload, this was the best-case scenario for the RSPduo. I tried different input levels from the KX2 and different dB offset and reference level settings on the software. Either the 2nd harmonic wouldn't show up at all or it only displayed when the fundamental (or the software) showed Overload.

    I will keep tinkering with it and make other measurements as well. For now, the 10 MHz BW is quite limiting - wider BW settings will be enabled in the next version of the program.