(replying to my own query!)
I found the option -- you double-tap in the SV window and it gives you options for intensity (waveform and graticle), and for x-axis lin/log
So, to set up Spectrum View you have to visit three menus: 1. SV in the channel badge, 2. double-tap the SV badge, and 3. double-tap in the SV window. who woulda thunk...