From Vacuum Tubes to Transistors/Integrated Circuits
Some of the earliest radio transmitters used spark gaps and high voltage to generate the power for communication. Communication was by Morse code. Very early radar systems used a rotary spark gap to generate pulses for the radar transmitter.
However, vacuum tubes came into wide spread use beginning in the 1920’s and 1930’s. They were used in all communications and navigational aide equipment. Vacuum tubes continued to be used into the 1970’s.
The transistor was invented in 1947; in the 1960’s transistors came into wide spread use. In the 1970’s, the integrated circuit (I.C.) became popular as well. Together, these made the miniaturization of equipment possible while at the same time allowing for even more capabilities than vacuum tube equipment. They also reduced the amount of maintenance required to sustain equipment.
Guide to tubes/transistors/IC's
1 – High power RF output for Transmitter
2 – Full wave rectifier (octal base)
3 – Reciever RF or IF amplifier (Loctal base)
4 – Low level audio amplifier (miniature)
5 – IF amplifier (miniature)
6 – Small signal audio transistor
7 – Small signal RF amplifier transistor
8 – Medium signal audio driver transistor (early)
9 – Small signal audio output transistor (early)
10 – Small signal RF amplifier transistor
11 – Small signal audio amplifier transistor
12 – Medium signal power transistor
13 – Large signal power output transistor
14 – Integrated circuit (14 pin DIP, includes 4 transistors)
15 – Integrated circuit (40 pin DIP, Central processor for computers)