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SA AMSAT EZINE
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AMSAT SA Space Symposium
10 July 2021
Presentation by Dr Gary Immelman ZS6YI
AfriCUBE Challenging the limits
Presentation by Anton Janovsky ZR6AIC
AMSAT SA Dual band 70cm/yagi Mark II
AMSAT SA has launched Mark II of is dual band 70cm/2m handheld beam antenna with a new, easier to hold handle and improved coaxial terminations. The Yagi has been retuned for maximum performance in the amateur radio 2 m and 70 cm satellite bands.
The coax cable is terminated crimped brass lugs instead of being soldered making it environmental more robust. The driven element has been adjusted to accommodate the change in the connection.
More about the Yagi
The antenna has a 50-ohm designed driver. 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.
The first South African version was a collaboration between Guy Eales ZS6GUY and Dr Gary Immelman ZS6YI. It was developed for YOTA 2018 where young people successfully used the antenna operating satellites using hand-held transceivers.
The mechanical structure was redesigned by Dr Gary Immelmann ZS6YI. A choke around the boom was added to isolate the antenna from the coax and reduce the effect human contact has on the antenna. A handle was added on the boom end which makes it more comfortable to hold and further isolates the antenna from the handler. The AMSAT SA yagi is manufactured in one of Dr Immelmann’s factories in Vereeniging. It has two elements on 145 MHz and 3 elements on 435 MHz.
For its size the antenna has excellent gain:
145 MHZ: 4.12 dBd or 6.3 dBi
435 MHz: 6.23 dBd or 8.4 dBi
The Yagi is broadband with measured SWR as follows and almost flat over the entire bands
The antenna is plug and play. No tools are needed except for soldering on a connector to suit the application. It comes complete in a carry bag with full instructions. This antenna can be assembled and dissembled in minutes.
The price of the MKII Yagi is R400 for AMSAT SA and SARL members. Non-members pay R500. The courier charge is R120 (Postnet to Postnet) Ask for a quote for other courier options.
Orderform click here
AMSAT SA Space SYMPOSIUM 2021
Saturday 10 July 2021
“Unlocking Amateur Space Technology”
Call for papers
In view of the continuing uncertainty about the Covid – 19 pandemic the conference will be a virtual event on the BlueJeans platform. The date is Saturday 10 July 2021 starting at 08:00 UTC.
The theme of the symposium is “Unlocking Amateur Space Technology”. The symposium will focus on amateur satellites, weak signal communication, space weather and allied sciences.
This is the first call for papers proposals. Prospective authors are invited to submit proposals in the form of a brief description of the subject to be covered in their paper by not later than 15 May 2021. Submit proposals in word format to email@example.com.
Authors will be advised on 20 May of the acceptance of their paper. The final paper will be required by 30 June 2021
AMSAT SA SUPPORTS SARL NEXT GENERATION BEACON PROJECT
VHF and UHF radio propagation remains a mystery; even tropospheric and sporadic-E propagation are not fully understood, with new long distance communication distance records being broken.
The enquiring nature of radio amateurs has over many years resulted in informal research with setting up beacons and monitoring signals. But this hand-to-mouth way of doing this has not really delivered the kind of data to make meaningful and scientific findings. All it’s really is showing is that long distance communication of frequencies above 30 MHz is possible and does regularly occur. The answer to the conundrum is to set up a reverse beacon network to monitor beacons. Reverse beacon monitoring has always been a major requirement for monitoring a beacon and has been discussed over the past two-plus years at various workshops arranged by the SARL and AMSATSA. The initial outcome of these deliberations was to monitor CW beacons using software like CW skimmer, but experience gained through actual testing has shown a number of flaws with this approach. The major flaw is that CW skimmer software is not 100% reliable when it comes to decoding. It requires a fairly strong signal before the software actually begins decoding the received CW signal. Aural reception of a weak CW signal can already take place way before the skimmer software starts to decode the signal. These findings encouraged members of the SARL VHF work group to start experimenting with digital modes like FT8 and JS8Call on VHF and UHF, and they found that the reception and reporting of the signals heard could take place at very low levels. This therefore seems to be a much better solution for a beacon than continuing with a traditional CW beacon.
Get the full story here
SARL NEXT GENERATION BEACON CROWD FUNDING
Current Fund R28 150
visit the SARL beacon page here Beacon
The SARL has provided funding for the
first beacon. However, the project will have to rely on crowd funding to
accelerate the project. AMSAT SA has launched a crowd funding project on
behalf of the SARL VHF work group.
Order 6 dualband AMSAT SA Yagi for delivery to Australia, UK and USA
R6000 courier charges included
Orderform here. Pay by credit card
RS, the component supplier in South Africa has become
a component sponsor for the KLETSkous project.
TRAX SPONSOR PCBs for KLETSkous More about TRAX
Avnet : a broad line supplier of semiconductors, passives, magnetics, enclosures, optoelectronic, GPS / GSM, interconnect, electromechanical, embedded products and components
Order for Mark (AUSTRALIA)