question by non-hobbiest

Never really had any interest in vintage electronics, more of a home theater guy (any questions about front projection systems, I'm your guy). However, somebody on my street threw out an old RCA Victor Model 7-T103. I hated to see that, so I grabbed it.

It's real clean, and in good shape from a looks standpoint. When I plug it in, a lot of vacuum tubes light up, and you get the tv hum, but no picture.

I was just curious to find out information about that model, year, whether it's at all rare, etc? Can anybody help me?

Thanks