HAMNET Report 24th March 2024

The amateur radio world has lost a huge font of knowledge of the measurement of RF signals as they are transmitted or received by radios in the amateur bands, with the passing last week of Adam Farson AB4OJ/VA7OJ, at the age of 84.

For many years, Adam has maintained a website of deeply insightful technical reports on all new ICOM products as they have been released, and has also co-administered a collection of groups.io on every ICOM radio as it came out. His reviews are extremely technical, but at the same time, not biased towards ICOM only, because he has compared them to Yaesu, Elecraft and Kenwood competitors along the way.

He immigrated to South Africa as a youngster with his parents in the 1960’s, and originally worked for Racal here, before moving to the UK, America, and finally Canada, which is where he died, of age-related causes.

Adam was an officer and a gentleman, with a great sense of humour, friendly and willing to share his knowledge and offer advice on any radio-related subject, no matter how simple the question asked of him. He will be greatly missed. The groups.io will continue, and his website will make all his reviews permanently available, so consider viewing his material on www.ab4oj.com/

A formal obituary to Adam has not been released yet, but he is deserving of the highest tributes.

Rob Sherwood, NC0B, of Sherwood Engineering is in the same category of super-giants, but he has specialized in the review of receivers, comparing all major brands with each other for sensitivity and selectivity, together with a host of other very technical parameters. His reviews are also available on the web.

I note that HAMNET Gauteng has had a change of leadership, with Regional and Deputy Regional Directors moving sideways, to take on a training role in improving member’s communications skills. Leon ZS6LMG and Johan ZS6DMX are to be thanked for their long years of service as directors, and I hope they rise to the challenge of the new duties. Until such time as a proper appointment of new regional and deputy directors is made, Brian ZS6YZ and Hannes ZS6EMS will hold the reigns, and we wish them well, as they fill in for Leon and Johan. Best wishes, fellows!

David Ingram, writing for NBC news says that several online retailers and drone technology companies are marketing the sale of radio frequency jammers as drone deterrence or privacy tools, sidestepping federal laws that prohibit such devices from being offered for sale in the U.S. 

Radio frequency jammers are devices that interfere with communications systems, usually by sending out competing radio signals to confuse nearby electronics. It is a decades-old technology that federal regulators have tried to crack down on, but interest in jammers persists because people can use them to keep away unwelcome drones, disable security cameras or block Wi-Fi networks. 

The Federal Communications Commission has warned that jammers can interfere with emergency communications, disrupt normal phone use and have other unintended consequences such as confusing airport navigation systems. According to the FCC, jammers are illegal to sell and may not be operated, marketed or imported into the United States. In general, even local police aren’t legally allowed to use them. 

“These jamming devices pose significant risks to public safety and potentially compromise other radio communications services,” the FCC says on its website. 

But those warnings haven’t stopped some companies from marketing the devices online. These companies take many forms: from Amazon third-party sellers to separate online stores based in China to small domestic companies that specialize in drone-related equipment.

After NBC News published this report, an FCC spokesperson said on Wednesday that the commission had several ongoing investigations into jammers. Those investigations have not been previously disclosed.

Thanks to nbcnews.com for this news.

In general, the average citizen is aware of RF jammers being used to block their attempts to lock their cars remotely as they walk away from them. I don’t know about you, but I unconsciously press my car’s remote button about 6 times as I leave my car, in case the first attempt was blocked. This is a simple form of the same jamming which the FCC is attempting to declare completely illegal.

A team of aroma chemists at Friedrich-Alexander-Universität Erlangen-Nürnberg, working with psychologist colleagues from the Technical University of Dresden, has uncovered the reasons for the dissimilar smells between babies and teenagers. The study is published in the journal Communications Chemistry.

Prior research and anecdotal evidence have shown that babies have a pleasant smell, often described as sweet. Teenagers, on the other hand, especially males, have often been described as smelling less pleasant. In this new effort, the research team sought to find out what causes the difference.

The researchers recruited the parents of 18 children aged up to 3 years old to wash the youngsters with a fragrance-free gel and to take swab samples of the armpits of their pyjamas prior to sleep. They did the same with 18 teenagers between the ages of 14 and 18. All the cotton pads were then collected and analysed in a lab setting.

The research team used mass spectrometry to identify the chemical compounds in the pads, and used gas chromatography along with a human sniffer to assess the odourousness of the smells associated with each chemical compound.

The researchers found that most of the chemicals responsible for body odour were similar between the two groups of volunteers. But there were a few that made the difference. Teenage sweat, for example, had high levels of many kinds of carboxylic acids, which the assessors described as “earthy, musty or cheesy.”

They also found two steroids in the teen sweat not present in the baby sweat, one of which resulted in “musk or urine-like” emanations—the other, the assessors suggested, smelled more like “musk and sandalwood.” Without such chemicals, the sweat of babies smelled much sweeter.

The researchers suggest that study of the chemical compounds in teen sweat could prove fruitful for makers of odour-control products. They also suggest that more work could be done better to understand the impact of such odours on parents.

Silly me! All along I thought the difference in smell was because one group washed, and the other group didn’t!

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