Updates! ...
Old portable CRT TV + Zeinth DTT900 DTV converter box:
57-83 channels found (did two scans): KCBS2, KNBC4, KTLA5, KABC7, KCAL9, KSCI18, 22, KCET28, ION30, 31, 34, 46, 52, 56, 57, KLCS58 (soso), 62, and 63.
Portable DTV (ATSC; Digital Prism):
88 channels found (wow): KCBS2, KNBC4, KTLA5, KABC7, KCAL9, 22, 28, ION30, 31, 34, 46, 52, 56, 57 (soso), 58, and 62.
Note that I gave the channel the station code/ID names for the ones I care for.
As you can see both of them are missing the ones I care for: KTTV11 (I watch FOX's shows a lot and sports sometimes), KCOP13 (I used to watch it for its Star Trek, but don't care any more), and KOCE50 (rarely though).
I find it amusing with a Terk FDTV1a Digital Pro antenna (vertical flat one), that my father/da/pa bought from Best Buy which I did not approve [sighs], worked for these missing stations: KCAL9 and KTTV11. The catch is that this antenna has to be on the middle the kitchen floor (no furnitures yet!) facing the garage's wall with an old central air condition (AC) unit throuhg the big window doors. LOL! That makes no sense though! There's wall! Maybe reflective from the wall and/or AC? Of course, this antenna is useless for every channels for its weakness (duh, we knew that).
I wonder if there something else to try to get KTTV11 and KCOP13. Then, I really don't need cable/satellite service!
I do need to test the channels again to be sure they are really that stable. As you noticed, some scans don't get all or missed them. I even tried forcing them like 11-1, but no signals.