Here is what I remember: This show aired during the daytime in the late 1970’s or early 1980’s on WITF, the PBS station in Harrisburg, PA. I don’t think it was locally produced though, so it probably aired on many PBS stations.
A girl and boy were the main characters, both American. They were helped by two “robots” who were more like machines in that they couldn’t move around. One looked like a fancy typewriter and would communicate by typing words. The other I think looked like a TV and had a voice but no face. Instead, when it spoke, a white light would go on and off on the TV screen. The show was kinda mysterious and sinister. I remember overtones that the boy and girl were reporters or some kind of journalists. Each show ended with a cliffhanger. The show was either 15 minutes or a half hour long, I don’t remember.
The distinguishing thing was the two robot/machine helpers. I’m positive about them.
Ring any bells with anyone?