I couldn’t wait for Monday when the wind will be down and weather expected to be good – I set up the Octagon LNB on the dish and pointed it out through the window. Tricky to point, but worth trying!
One problem is that I don’t really know what I’m looking for as far as broadcast satellite signals are concerned. A second (slight) problem is that the gqrx display bandwidth is only 200kHz, as I had forgotten how to change it, so it’s hard to get a broad picture. I’ve found out how now, so that will make things a bit easier next time.
The signal in the screenshot is from a satellite at (I think) around 5° E. The 964MHz IF corresponds to 10714MHz into the LNB. At least my setup can receive something from a geostationary satellite. The steps in the waterfall are due to me changing the frequency.
I haven’t managed to find the Astra satellite at 28° E yet, but don’t really know what the signal looks like. It will be easier out of doors next time I try.