 Four radio masts mounted at 90 degree intervals on the base of the satellite and two experimental repeater systems provided store-and-forward for Morse code and teletype messages ("codestore") as it orbited around the world.The Mode-B transponder was designed and build by Karl Meinzer, DJ4ZC and Werner Haas, DJ5KQ.The Mode-B transponder was the first using “HELAPS” (High Efficient Linear Amplification by Parametric Synthesis) technology was developed by Dr. Karl Meinzer as part of his Ph.D. research.