Abstract: A modular amplifier comprising a plurality of modules receives a signal to be amplified and provides an amplified signal through power divider and power combiner circuits which are mirror images of each other. In particular, 2-way Wilkinson hybrid circuits are combined to deliver the input signal by providing a divided signal to each of the amplifier modules. The output of each of the modules is combined by 2-way Wilkinson hybrid circuits to provide the amplified signal output. In order to provide discrete power reduction switching from a full power condition to a reduced power condition, at least one of the inputs to a module is connected to a quarter-wave stub which is selectively grounded and open-circuited to reflect respectively an open circuit and a short circuit condition. In this way, each amplifier module performs similarly in the reduced power output condition as well as in the full power output condition.

Abstract: Dimeric indole alkolids-vinblastine, des-N-methyl-vinblastine and vincristine-are purified by extracting leaves of Vinca rosea with acid, neutralizing the acidic solution, extracting the dimeric alkaloids into an aromatic solvent, optionally subjecting the extracted alkaloids to gel exclusion chromatography, precipitating the dimeric alkaloids as sulfate salts and finally separating the dimeric alkaloids by high-pressure chromatography.