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Mondays 18:30 CAT
SA AMSAT EZINE
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AMAZING CONTACTS ON 46 YEAR OLD AMATEUR RADIO SATELLITE
Tom Ambrose ZS1TA, from Cape Town has recently reported AO-7 contacts. Why is this remarkable? There are plenty of satellites up there!
Well, the satellite was launched on 15 November 1974 which is 46 years ago. Technology has progressed dramatically since then. The satellite went silent due to a faulty battery in 1981. That was 7 years after launch which was a good life for a satellite designed to be operational for 3 years. In 2002, 21 years since it went silent, one of the shorted batteries became open circuit and the spacecraft was able to operate off its solar panels again. It can operate while in sunlight, so its operation is intermittent, but it is still being reported almost daily since January 2020. Read more, listen to contact and view video here
For the past year, in parallel with the development of |Kletskous), analogue CubeSat, AMSAT SA teams have been working on a digital software defined transponder named AfriCUBE. For many of its functions the digital version relies on a Raspberry Pi 4.
‘While the latest version of the analogue transponder performed well during a high balloon test flight into near space last October, it showed that further development was needed to improve the transponder’s receiver sensitivity. This prompted our decision to prioritise the digital SDR development”, Project team leader, Dr Hannes Coetzee (ZS6BZP) said. “Prioritising the digital transponder enhances our opportunity to have it considered for inclusion on the South African Space Agency’s EOSAT-1 project, a high-performance Earth-Observation satellite designed to produce data for a broad range of Earth observation applications.”
The main driver behind the AfriCUBE project is Anton Janovsky (ZR6AIC) who is assisted by a team of volunteers.
AMSAT SA have not abandoned work on the analogue transponder and are looking for budding engineers to join the team. Interested volunteers should email their details to email@example.com. Get the full story here
Join the AMSAT SA CubeSat team
AMSAT SA invites radio amateurs with RF, electronic and software experience to join the Satellite Development team and make a contribution to technology and human capital development in South Africa. The team meets every alternate Monday on a Skype conference and quarterly face-to-face. Send your contact details and your main interest in the CubeSat project to firstname.lastname@example.org. Hannes Coetzee ZS6BZP or another team member will contact you.
AMSAT SA Dual Band Yagi
FOR EXPORT IF ORDERED IN BATCHES OF 6 UNITS
Following requests from many amateurs outside South Africa we can offer the yagi for export if ordered in a batch of 6, at R950 each (approx US $65), total for a batch of 6 R5700. (approx US $ 390). Available to countries in the European Union and the USA. The Yagi has a unique element called a ‘Open Sleeve’ which is a director very close to the driven element. The driven element is sized for 2M. When operating on 70cm the ‘Open Sleeve’ acts as part of the driven element on 70cm (Third harmonic of 2M).
The original concept was developed in 1946 by Dr J T Bolljahn of the Stanford Research institute but was not introduced into amateur radio until the 1950s. The AMSAT SA version is based on a design by DK7ZB with modifications by WB5CXC. More details and order form here. Order form for South Africa here
The downlink frequency is 10 489.550 to 10 489.800 MHz with the centre of the band being 10 489.675 MHz. Vertical polarization will be used.
The preferred modes of operation will be SSB and CW. 5 Watt uplink power to a 60 to 75 cm offset dish should be more than sufficient for the uplink. The transponder will also be fitted with a “LEILA” (LEIstungs Limit Anzeige) input power limiter to ensure fair play and that the AGC of the transponder is not triggered (hogged) by a single, high power transmission, thus reducing the sensitivity of the satellite. In short, running higher uplink power than necessary will be counterproductive,
A detailed paper was presented by Hannes Coetzee ZS6BZP at the 2018 AMSAT SA Space Symposium. Plans are being made to have a live demonstration at the 2019 AMSAT SA Space Symposium on 16 March 2019. Down the ZS6BZP paper here.
AMSAT SA SPACE SYMPOSIUM 2020 First call for papers
Amateur Radio in Space – exploring VHF, UHF and Microwaves
Papers are invited for presentation at the conference and publication on the web. Please send your synopsis by 28 February 2020 in a word document of no more than 300 words to email@example.com.
Please tell us if you will be available to present your paper at the conference.Speakers attend free.
DATE: 11July 2020
Note new date
Venue: Premier Hotel Midrand
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a component sponsor for the KLETSkous project.
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