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AMSAT SA
Registered as a non-profit company
Registration 2016/111111/08
Follow AMSAT SA on FaceBook https://www.facebook.com/AmsatSA00/
AMSAT SA
P O Box 90438
Garsfontein 0042
South Africa
Tel: 082 781 4631
Email:
admin@amsatsa.org.za
Weekly satellite News
Amateur Radio Today is
Sundays 10:00 CAT
7082 kHz
Mondays 18:30 CAT
3230 kHz
Quick links
listen to Focus on VHF and above here
Previous conference presentations
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 R150 (Postnet to Postnet) Ask for a quote for other courier options. Get order form here
SARL NEXT GENERATION BEACON CROWD FUNDING
Current Fund R30 400
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.
Contributions can be made by clicking on the pay button for R50,
R250 or R1000. Your contribution is appreciated and will be
acknowledged.
R50
R250
R1000.00
Thank You. You an make it happen!
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