"Squashed" DTV picture on analog CRT TV

[Jeffhs]

My RCA CTC185 CRT TV works well on cable, but lately I've noticed the pictures on most cable channels do not fill the screen vertically. This set was working perfectly well before the DTV transition; has something happened to the TV since then (it has not been used much since I've had a flat screen), or is this just the way analog CRT TVs handle digital TV signals? My Zenith Sentry 2 CRT set does the same thing, so I seriously doubt the set itself is at fault. I wouldn't be concerned about this too much, but I intend to use one of these sets as a daily watcher if and when my flat screen quits; I don't want to have to use a cable box if it isn't necessary to get a full picture.

Thanks much.