20m WSPR at 50mW to a low end-fed antenna

I went QRT on 10m and 6m WSPR and switched instead to 50mW on 20m WSPR.  At this power I am still getting spotted. I am reducing power with a 10dB attenuator and 500mW from the FT817. This means I have a 10dB pad in circuit on RX. Even with this some stations are 0dB S/N on RX.

UPDATE 2056z:  Even with 50mW some spots were as strong as -2dB S/N. Later in the week I may make a 30dB attenuator so I can go as low as 500uW and try this. With very low output it is possible I'll still get the odd spot, especially by wintertime Es. Best DX spot today on 20m WSPR was 1200km, so far, from IQ5LU late lunchtime. I shall leave the 20m WSPR running overnight.

UPDATE 2121z:   The more recent spots by DL2JA (919km) of my 50mW 20m WSPR had lots of drift. This could be aircraft reflection, Es clouds moving or rig drift.