Skip to Main Content
Design of distributed power amplifiers has been simplified through the use of a set of design charts and simplifying circuit techniques. A circuit in which the anode and grid lines are built from bridge-T constant-resistance networks seems to be best. These lines have an image impedance that is resistive and of constant value for all frequencies, and therefore do not require terminating half sections. For a given characteristic impedance and shunt capacitance, the bridge-T lines have about twice the bandwidth of the constant-K lines. The design of the ferrite transformers for matching the anode and grid lines to standard line impedances has been simplified by means of design charts and tables. These amplifiers are simple to build and very stable. A 3.5-kW amplifier which operates from 1.0 to 70 MHz is used to illustrate the technique.