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RS assists radio amateurs to gain access to satellite for R&D purposes

RS South Africa is one of the component sponsors of the SA AMSAT (South African Amateur Radio Satellite Association) amateur radio CubeSat project called KLETSKOUS. The CubeSat is being developed and built by radio amateurs.

titleThe mission of KLETSKOUS is to give radio amateurs (and educational institutions) in Southern Africa, easy access to an amateur radio transponder on a Low Earth Orbit (LEO) satellite on as many of the available passes as possible and thus stimulating interest and activity in space, satellites and amateur radio, the world’s best technical hobby

The transponder uplink will be on the amateur 70 cm band, and the downlink on the 2 m amateur band. The linear transponder with a bandwidth of 20 kHz will support FM, SSB and various data modes. A sub-carrier for a telemetry downlink will be included. For command and control purposes a separate 70 cm frequency will be used.

The latest contribution from RS for this project is again components for the satellite power unit. The project leader for this part of KLETSKOUS is Fritz Sutherland jnr.

He has already built most of the sub-systems on the higher voltage design. The higher voltage of a 2 cell Li-ion battery simplifies the design somewhat because there is more voltage available to 'play' with, and the current through most of the parts are lower.

In order to work with this 2-cell design the voltage supplied by the solar panel had to be boosted. This could either be done by a DC-to-DC converter in boost-configuration, or by reconnecting the individual cells within the solar panel in a different series/parallel configuration. The test-panel currently consists of 20 individual (Spectrolab TASC) solar cells. Each cell has an open-circuit voltage (Voc) of 2.52V and a maximum power point (Vmp) at 2.19V (at standard test illumination). By connecting 5 cells in series and 4 sets in parallel, the panel then delivers an open circuit voltage of 12.6V and the maximum power point is just below 11V.

The rest of the power system's components are 2 DC-to-DC converters in buck configuration to deliver the system power at 3V3 and 5V. There is also a buck-regulator driven charge controller circuit for the Li-ion battery, along with a disconnection switch which can be activated from the main controller once the battery has completely died.

All of this has been built on bread-board and tested, including a throttling mechanism on the battery charger. The idea is to limit the battery charge-current when the solar panels are unable to deliver enough power to keep the battery charger and the load running simultaneously.

titleThe first version of the PCB has been laid out and produced. Fritz will start the process of populating the board with most of the components supplied by RS. Once it is completed, several tests will be done to confirm that the EPS is working as designed, and then it needs to be integrated with the other sub-systems of the satellite. Once that has been completed, all the changes that were required on the first version of the PCB will be transferred to a second version and the process will be repeated. The second version will then be used as a flight test board to confirm that everything still works while flying at high altitudes.

Keep a look out for future developments on KLETSKOUS! Thanks to RS South Africa for supporting this initiative.

Written by Hans van de Groenendaal (SA AMSAT)

Read more about this exciting mission - SA AMSAT 

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