Homebrew 500 watt HF power amplifier

Jeff (K6JCA) has written a series of posts describing his homebrew project 500 watt HF power amplifier:

I started this project back in 2016 — I had finished my Automatic Antenna Tuner (seen in the upper-left of the picture, above) and a PA project that would integrate into my FPGA-SDR and ATU system seemed like the ideal next step.
While researching RF amplifiers, I discovered a Microsemi App Note, “A 700W Broadband Amplifier using VRF2944”. I decided to use its design as the basis of my PA and began gathering parts.

See the full post on K6JCA blog.

from Dangerous Prototypes https://ift.tt/2YrsTcf

Pattern Makers: Notes from Session 2 of TEDWomen 2019

“You don’t predict the future, you imagine the future,” says author Charlie Jane Anders. She speaks at TEDWomen 2019: Bold + Brilliant, on December 5, 2019 in Palm Springs, California. (Photo: Marla Aufmuth / TED)

In Session 2 of TEDWomen 2019, we meet some extraordinary pattern makers:  people helping us predict the future, improve our relationship to technology and unearth powerful discoveries.

The event: TEDWomen 2019, Session 2: Pattern Makers, hosted by Pat Mitchell and Cloe Shasha

When and where: Thursday, December 5, 2019, 8:30am PT, at La Quinta Resort & Club in La Quinta, California

Speakers: Lucy King, Jennifer Zhu Scott, Angie Murimirwa, Jiabao Li, Eva Galperin, Charlie Jane Anders

The talks in brief:

Lucy King, elephant advocate

Big idea: As their foraging territories shrink, African elephants encroach more and more on agricultural lands — and as a result, upset a delicate balance between elephants and their once-tolerant human neighbors. Amidst ever-more-frequent cases of hungry elephants devouring crops and wrecking farmhouses, Lucy King developed an innovative method to bar elephants from cultivated fields without erecting huge (and often ineffective) electric fences.

How? Through research inspired by local folklore, King discovered that elephants avoid beehives and the painful stings of their inhabitants. As a result, she developed “beehive fences” that release swarms of insects when elephants attempt to breach them, sending the pachyderms packing. In tandem with these fences, King’s “Human-Elephant Co-Existence Program” encourages farmers to plant crops that pollinators love and elephants hate — and that can help farmers establish new livelihoods.

Quote of the talk: “Can you imagine the terror of an elephant literally ripping the roof off your mud hut in the middle of the night, and having to hold your children away as the trunk reaches in looking for food in the pitch dark?”


Jennifer Zhu Scott, entrepreneur and technologist

Big idea: Our personal data is a valuable asset — but we’re not getting paid for it. Giving individuals pricing power over their own data could reduce inequality by empowering people instead of businesses.

Why? Data: the most successful companies in the world are either built on it or profit from it. We the people are producing this data, so why aren’t we getting a paycheck? Data ownership is a personal and economic issue, says Jennifer Zhu Scott, yet too often our conversations fixate on data privacy and regulation instead of the potential prosperity it can bring. And for some, this ownership could be a path out of poverty. Take Zhu Scott’s home country of China — a society that saw its extreme poverty rate drop from 88 percent in 1981 to 0.7 percent by 2015. It wasn’t a perfect transition by any means, she says, but this transformation is a case study for how personal ownership can improve people’s lives. We can create an economic model where individuals control and barter their own personal data, instead of letting Facebook or Tencent do it — and startups are already creating tools to make this a reality.

Quote of the talk: “Whoever owns the data owns the future.”


Angie Murimirwa, education activist, executive director of the Campaign for Female Education for Africa

Big idea: “Social interest,” or paying back interest on a loan through service rather than dollars, can promote economic prosperity in communities across Africa — helping girls stay in school, get job training and obtain and pay off loans.

How? Young women in sub-Saharan Africa often can’t afford school and have difficulty finding consistent wages and loans, keeping them trapped in a vicious cycle of poverty and inequality. Angie Murimirwa believes that the solution to this economic landscape lies in empowering young people through “social interest” — a kind of loan interest that can be paid off by service, such as mentorship and teaching, instead of traditional currency. Not only has social interest facilitated Murimirwa’s own success, but she has also watched it benefit thousands of others. In fact, nearly 6,300 young women have borrowed close to three million dollars — with a repayment rate above 95 percent. 

Quote of the talk: “We are building a powerful force gaining ever greater momentum, as we open the door for more and more girls to go to school, succeed, lead and, in turn, support thousands more.”


Jiabao Li, artist and engineer

Big idea: Technology affects the way we perceive reality, creating a hyper-fragmented humanity vulnerable to seemingly “mental” allergies. But as with many cures, the problem gives insight into the solution.

How? To emphasize this human-made phenomenon, Jiabao Li created a series of perceptual machines to help question the ways we experience the world in the age of digital media. Her conceptual designs include a bulbous helmet that mimics the amplification effect of social media, and two web browser plug-ins — one that would help us notice things we’d usually ignore, and another that would dilute algorithmic influence. Technology is designed to change what we see and what we think, and in many ways it’s separated us — but we could use it to make the world connected again.

Quote of the talk: “By exploring how we interface with these technologies, I hope we could step out of our habitual, almost machine-like behaviors, and finally find common ground between each other.”


Eva Galperin, cybersecurity expert and technical advisor

Big idea: Stalkerware is on the rise. We need to educate the public on how to protect themselves and convince antivirus companies to begin detecting it.

How? Eva Galperin was shocked to discover that an alarming number of people are being hacked by their current or former partners. A common and particularly insidious form of this modern-day abuse is “stalkerware,” software designed to track or spy on someone without their knowledge. Stalkers simply buy the program, install it on their victim’s devices and pay the software company for remote access, letting them see their victim’s every movement, text message or email. When Galperin discovered that most antivirus softwares do not detect these programs, she launched the Coalition Against Stalkerware to raise awareness and advocate for antivirus companies to begin detecting it. She hopes that by next year, antivirus software will be able to offer stalkerware detection to discourage abusers and protect victims. 

Quote of the talk: “Full access to a person’s phone is the next best thing to full access to a person’s mind.”


Charlie Jane Anders, author and futurist

Big Idea: Dreaming about our collective future is the first step toward creating a better one.

How: The world is changing so fast that no one — not even futurists like Charlie Jane Anders — can predict what it will look like in a few years. Now, she vaccinates herself against the acute onset of future shock by imagining it in all its wild possibilities, instead of trying to predict it. In a process that’s part fever dream and part research-based extrapolation, she constructs future worlds by living them through her characters and speculating about the delights and challenges that could arise. It’s by engaging in such directed flights of fancy, Anders suggests, that we can begin constructing a better world of tomorrow. 

Quote of the talk: “You don’t predict the future, you imagine the future.”

from TED Blog https://ift.tt/2s0tlSu

‘The Boys’, la brutal serie anti-superhéroes de Amazon, estrena el primer tráiler de su segunda temporada

'The Boys', la brutal serie anti-superhéroes de Amazon, estrena el primer tráiler de su segunda temporada

‘The Boys’ fue una de las más gratas sorpresa de 2019, un soplo de aire fresco ante la saturación de historias heroicas de superhéroes. Y es que aquí estábamos ante todo lo contrario, un mundo donde los superhéroes son una especie de dioses que son controlados por una mega corporación, que precisamente se dedica a proteger sus oscuros secretos.

Por tal motivo, ‘The Boys’ se convirtió en la serie más exitosa de Amazon Prime Video durante el año, por lo que era obvio que tendría una segunda temporada. Esta nueva temporada llegará en 2020, en una fecha aún por confirmar, pero ya tenemos el primer adelanto en forma de teaser tráiler sin diálogos, donde las imágenes hablan por sí solas. Leer más