Figure 4 eh.7. Small signal model of a triode. There are two terminals on the left labeled G and K. The K terminal goes to the common line of the circuit. The G terminal goes to nothing as the grid of a tube is an open circuit. An AC voltage source is labeled minus mu times v sub g k. This source is drawn vertically. The bottom end of the source is connected to common. The top of the source is connected to one end of a resistor labeled r sub p. the r is lower case. The other end of the resistor connects to a terminal connection which is labeled P. Below this terminal is another one which is labeled K and is connected to the common line. Connected between the two terminals are two resistors in parallel. They are labeled Rb and Rcf. This time the letter R is upper case. End verbal description.