National Director Paul van Spronsen ZS1V has announced the new-look HAMNET website, accessible at hamnet.co.za. A basic description of emergency communications is provided on the home page, the weekly news bulletin you are listening to now is printed on the news page, a page for news from all the divisions is next, to be populated with news by a designated reporter from each division, and then a page for operations reports and another for event reports. Calls for volunteers to help with activities may be placed here too. The website is open and available for all to read, and we hope you will learn to access it regularly to keep up with HAMNET news in South Africa.
A very clear and concise discussion of the types of solar panels available and their uses has been provided by Chris Warren, who runs a blog called “Off Grid Ham”. He notes that hams are not well versed with the attributes of the 3 types of solar panels available: Monocrystalline, Polycrystalline, and Thin Film.
Monocrystalline panels use high quality silicon cut into individual cells, attached to each other and seen as small separate patches on the panel with electrical connections. Polycrystalline panels have molten silicon poured into a mould. They have thin metallic wires dividing the panel into cells, but are in actual fact one single large patch. Thin film panels have a silicon photo-reactive semiconductor applied to a substrate, usually thick plastic. These latter are flexible and may be rolled up.
Monocrystalline panels are more efficient than polycrystalline panels, producing 4% more wattage per square metre, and have a longer service life and a greater tolerance for extreme temperatures, but the differences do not justify the extra price per square metre of panel, not in the kind of sizes used by radio amateurs. Both systems’ service life can run over two decades, more that you might ever need.
Thin film panels are inexpensive when used at low power levels, and are freely available. Their flexibility also carries an advantage if you are doing a Summit On The Air activation and want to carry them up a mountain! They are usually below 10% efficient, compared to about 13% for Polycrystalline and about 19% for Monocrystalline panels.
On balance, you will get the most wattage for your sized total panel layout per Rand spent on a polycrystalline panel system, their slightly lesser performance compared to monocrystalline panels more than offset by the reduced cost. And if you’re thinking of spending money rigging up a sun-following panel system, let me tell you that it would be cheaper to buy another polycrystalline panel or two and gather more sunlight that way, than to have your smaller layout follow the Sun.
Thanks to Chris Warren for the concise summary.
This week’s ARRL newsletter carries a mention of a training Webinar set for 24th July, hosted by Ward Silver N0AX, entitled “Contesting as Training for Public Service”.
“Think of contests as a ham radio fitness centre,” Silver said. “Public service teams are always looking for enjoyable activities to improve operator skills. Just as sports provide good physical exercise, contests are great at developing radio skills, and both are a lot of fun.” Silver pointed out that contests originated as a way to hone traffic-handling skills and develop an effective station.
The ARRL’s recent National Field Day is a good example of a huge experiment, by thousands of hams, working in groups mostly, working to test their radios, antenna systems, and off-grid power systems, with a view to establishing an understanding of the best way they can offer an emergency service in time of need. It is just unfortunate that this year’s solar conditions are so poor that high numbers of QSO’s were not possible.
Astronomy Magazine’s weekly newsletter tells us that China’s Five hundred metre Aperture Spherical Telescope, or FAST, has been completed 3 months ahead of schedule. The surface area of the radio dish is equivalent to that of 30 soccer fields, it cost $180 million to build, and took 5 years to complete.
FAST is tasked with many projects involving studying strange objects such as quasars, pulsars, and gravitational waves, as well as searching for extra-terrestrial life, all with the intention of understanding better the origin of the universe.
The previous biggest radio-telescope is the 305m Arecibo dish in Puerto Rico, which has been doing similar research for 40 years. From there the most powerful broadcast ever deliberately beamed into space was made in 1974. A megawatt transmitter’s signal was concentrated into a beam, equivalent to a 20 trillion watt omnidirectional broadcast, but aimed at an area in the globular cluster M13 about 21000 light-years from us, and containing about 300 000 stars. The total broadcast took less than 3 minutes to send, and consisted of 1679 bits of information, sent by frequency shift keying, at the rate of 10 bits per second. An answer from the stars is not expected any time soon, so don’t hold your breath.
The experiment was useful in getting us to think a bit about the difficulties of communicating across space, time, and presumably a wide culture gap!
This is Dave Reece ZS1DFR reporting for HAMNET in South Africa.