SPS RF System in BA3: Tetrode power amplifiers and high power coaxial lines

<!--HTML-->This picture shows one of the initially installed amplifier units of the SPS RF system. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also gradually increased: in 1980 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also <a href="https://cds.cern.ch/record/916924">7412017X</a>, <a href="https://cds.cern.ch/record/916919">7411048X</a>.