I have to say, I really enjoyed the Time Tunnel, until a certain crutial point where it became disappointing to watch. What was this you ask? Well once they brought up Aliens, that ruined the series. The producers seemed to have run out of ideas to keep feeding into the scripts. Aliens and outer space was good only ONCE, not 5 or 6 times.
Aside from aliens, the show was very well written and well cast. Though the fighting dials was very unreal, it made for good entertainment. They could sucessfully send people back, but they could never bring them forward.
Anyways, this show is very good and out on DVD, check it out, there is lots of historical information and a bonus re-launch episode of the Time Tunnel from 2002!