Jack and Bruce - many thanks. It all helps to work out what's happening.
I only posted a photo of what I saw with the default calibration where the SA is automatically set at 10dB. It's the exact same image I'm seeing when I force it into 0dB setting. So I'm getting nothing with 0 and 10dB. I've now taken pictures of what I see on the other settings from 20 to 70dB. I did try to describe these in another post, but a pictures worth a thousand words so I've attached pix for 20, 30, 40, 50, 60 and 70dB attenuation. Enjoy...
Jinxie
