Basic Radio is a free introductory textbook on electronics based on tubes. See the editorial for more information....


Author: J.B. Hoag

In order to call attention to the necessity of shielding each stage and each decoupling unit from the rest of the circuit, the complete circuit of a linear amplifier is shown in Fig. 25 D.

Fig. 25 D. A linear amplifier, filtered and shielded

A linear amplifier is one in which the output voltage is directly proportional to the input voltage. In the figure, the dotted lines represent metal shields. In this circuit, the first tube must be. non-microphonic, of fairly high input resistance, and of low input capacity. Noises which might originate in this tube are minimized by operating it at subnormal voltages. See also Sec. 7.3 for additional discussion of shielding.

Last Update: 2009-11-01