HAMNET Report 6th June 2021

As forecast, the central Eastern Cape, Lesotho and the Drakensberg received a fair amount of snow this week. High ground around Barkly East, Rhodes and Tiffindell in the Eastern Cape, and Bethlehem, Warden, Reitz and Harrismith in the Free State were to be well blanketed, and possibly areas around Newcastle in KZN and Volksrust in Mpumalanga.

Travelers are advised to take plenty of warm cover and protective clothing, and also be well stocked with food and liquids in case they get stuck along their routes, as driving in snow, even if light, is very challenging, and it is easy to lose control of a vehicle and end up in a ditch.

The whole country is experiencing cold nights, except perhaps the KZN coastline, but typical Western Cape rains haven’t really started yet. Days are balmy and still, and autumn sunsets are spectacular in Cape Town.

All radio amateurs are asked to have their radios on, monitoring or scanning their local repeaters, and keeping an ear on 3760 KHz, 7110 KHz, and 14.300 MHz, for emergency traffic. Please be available to help your fellow South African.

Brian Jacobs ZS6YZ, HAMNET Deputy National Director, has sent me an interesting tale from Division six. He reports that flying is a very dangerous hobby, even more so if you need to fly and there’s interference on the radio frequency you have to use to communicate with other pilots in the same flying area.

This happened in the Special Rules Area East in the Gauteng area where 125.400 MHz had a constant carrier that made it very dangerous and basically unusable.

This was a big concern as this frequency is used over a great area, from the south of Johannesburg to the north of Pretoria and from O.R.Tambo Airport all the way to Bronkhorstspruit in the east.

On the 7th of April 2021 HAMNET Gauteng was made aware of the situation,  and they immediately offered the skills of Team Interdiction (this being a code name for the HAMNET Gauteng interference specialist team) to locate the source of the interference.

Seventeen members of HAMNET Gauteng joined the hunt. Every night the teams went out to locate the source. About 60 man hours were spent.

Leon ZS6LMG got a strong signal close to O.R.Tambo airport cargo area and asked ICASA to assist (as HAMNET does not have the power to enter premises and has to rely on the goodwill of people to open if asked).

ICASA came out and started looking for this signal source and found that the signal origin was not at the airport but more to the west. On Friday the 16th Henry ZS6IIX used a 7 element UHF Yagi and a USRP SDR from his home and got a bearing of the source. He then used a 3 element Yagi just to confirm that the signal was not a reflection off a building or any other structures.

The signal was coming from the North West.

On Saturday at the HAMNET meeting he suggested that somebody close to the Magaliesberg area be asked to drive out there and see if the signal was coming from that side. Awie ZS6AVI, staying in the Randburg area, volunteered to drive out that way on Monday before going to work and there he found a very very strong signal at Hekpoort School (even with the antenna removed from his mobile radio).

On Wednesday Henry ZS6IIX drove out to Hekpoort armed with a R&S FH3 Spectrum Analyser, a USRP SDR, a 100 dBm attenuator, a Dell Laptop and other odds and ends. He did a RF simulation and found the source to up the mountain. He and Leon informed ICASA, whose inspector confirmed the location and contacted the owners of the site.

It turned out that the interference was caused by an Airband transmitter whose PTT locked on after load shedding and the generator had kicked in. The owners went out and switched off the transmitter.

Brian notes that the strong signal on a high site caught a lot of interference experts out, and that Team Interdiction is adjusting its protocols for engaging strong signal interference.

On behalf of HAMNET Gauteng, Brian thanks all the pilots and aviation personnel that gave feedback on the areas of interference. Special thanks are due to the ARCC Chief for collating the pilot reports and feeding it to Team Interdiction.

And thank you Brian for that welcome report from Gauteng, compiled by Henry Rood ZS6IIX. My apologies for not listing the names and call signs of all seventeen HAMNET members involved.

The amateur radio fraternity as well as the radio astronomy fraternity has lost a giant of a man, with the passing, at age 95, of Emeritus Professor Gordon Pettengill, W1OUN. He was the former Professor of planetary physics and former director of the MIT Centre for Space Research, and a great pioneer in radio astronomy.

Pettengill pioneered the use of radar for planetary astronomy applications, making ground-breaking observations of the moon, the inner planets, and other solar system objects. His work was instrumental in the development of multiple NASA missions including the Apollo moon missions and the Mariner 2, Pioneer, and Magellan missions to Venus.

Interested in matters electronic since the age of six, he acquired his amateur licence in his teens, but his studies in Physics at MIT were interrupted by
World War 2. He finally finished his Ph.D in high-energy physics in 1955.

He returned to MIT just as a special government-funded experimental missile-tracking radar system was being built there, and with it, he made break-through observations in the developing field of radio astronomy. He aimed the system at Venus, and measured its distance by radar, recalibrating the astronomical unit by three orders of magnitude. He was able to generate a 2D radar map of the moon, used by NASA to plan future Apollo landings.

In 1963, he moved and eventually became director of the new Aricebo Radio Observatory in Puerto Rico. He helped with the installation of the powerful radar transmitter used to measure Mercury’s period of rotation, and also described surface properties of several asteroids and comet nuclei.

There were not many awards he did not win, but he retired in 1995, and pursued his hobbies of ham radio and bird-watching. Quaintly, he is quoted as being survived by his wife, two children, two grand-daughters, and an asteroid named 3831 Pettengill!

Not many of us will be able to boast something like that.

Thanks to MIT News for this abbreviated version of his obituary.

This is Dave Reece ZS1DFR reporting for HAMNET in South Africa.