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|