The GE Compactron 1960-1975

The transistor in 1960 was still an expensive component compared to vacuum tubes. General Electric engineers designed a lower profile but larger footprint vacuum tube that could contain as much as 5 separate vacuum tubes in an envelope. They patented the design and named it the Compactron. The Compactron is a 12 pin vacuum tube with the base design similar to the 7 and 9 pin miniature tubes. These tubes were designed for PC mounting and were mainly designed for television. Television makers can now reduce the tube count from say 12 to 6 and if any transistors were used to 3 or 4. It help reduce production cost and kept vacuum tubes in production for at least 5 years. During this transition period, TV's were hybrid  using both tubes and transistors. Often when you turn on a 1960's TV the sound would come on instantly and you had to wait about 20 seconds for the picture to come on. Often it is probably a hybrid TV. Many television manufacturers would taut being "transistorized" or "solid state", but they still had maybe two or three Compactron tubes. The damper and horizontal output tubes were the hardest to replace with transistors because of large pulse handling requirements. Many Compactrons were combo damper/horizontal output tubes like the 33GY7 and 38HE7. If you took  the time to study the tubes, they were established tubes stuffed into one envelope. Example is the 6B10 tube data sheet on the left. It is basically the design of the 6AV6 tube triode and diode parts.