LF disappointment

Yesterday evening and overnight I was on 136kHz WSPR RX with a preamp in circuit. Only 2 stations were spotted - G3XIZ (46km) and G8HUH (250km) and, if I am honest, the preamp made little difference, whereas I was hoping for much more.

With G3XIZ there may have been a slight improvement but with G8HUH he was no better. I am not quite sure what this is telling me. I think it means external noise is the limiting factor at this QTH. Unless I take further steps to reduce the external noise I am unlikely to spot many more stations. There was one station on OPERA (G3XDV?) who was quite strong, but I did not have any OPERA software running. I shall try again tonight. If possible, I'll run both WSPR and OPERA software at the same time.