As a radio amateur, you have likely run across these crystals in countless parts bins, swap meets, and vintage schematics. The reason 43.333 MHz crystals are so common comes down to a classic, elegant piece of frequency math that bridged the gap between early VHF operation and standard HF rigs: the 2-meter to 20-meter transverter/converter.
The 2-Meter to 20-Meter Magic Number
Historically, amateur radio operators wanted a way to receive and transmit on the 2-meter band (144–146 MHz) using their highly sensitive, existing 20-meter HF receivers (14 MHz) as a tunable Intermediate Frequency (IF).
To mix a 144 MHz signal down to a 14 MHz IF, you need a highly stable 130 MHz local oscillator (LO):
144 MHz (RF) - 130 MHz (LO) = 14 MHz (IF)
Creating a stable, fundamental-frequency quartz crystal at 130 MHz was physically impossible for decades because the quartz wafer would have to be sliced microscopically thin and would easily shatter.
Instead, designers utilized a robust, lower-frequency third-overtone crystal operating at 43.333 MHz. When you multiply 43.333 MHz by three in a simple tripler stage, you get exactly the 130 MHz LO signal needed:
43.333 MHz times 3 = 130 MHz
Why They Flooded the Market
Because the 2m-to-20m conversion was the gold standard for VHF operation in the 1960s, 70s, and 80s, these crystals were mass-produced. They were the heart of legendary gear like the Drake SC-2 receiver converter and dozens of homebrew transverter designs featured in the ARRL Handbook and 73 Magazine.
If a ham wanted to monitor the popular 146.94 MHz repeater frequency of the era, they would use a 2-meter converter with this exact crystal, allowing them to tune their HF dial to precisely 16.94 MHz.
Other Multiplier Matches
Additionally, 43.333 MHz has convenient harmonics for other bands. For instance, multiplying it by 10 yields 433.33 MHz, which sits perfectly inside the 70-centimeter amateur band and the widely used 433 MHz ISM band (common for low-power key fobs, weather stations, and remote controls).
Whenever you see a strangely specific, non-integer crystal frequency like 43.333 MHz, 38.667 MHz (used for 2m to 10m conversions), or the famous 3.579545 MHz color burst crystal, there is almost always a legacy of mass-production and clever math behind it!
This is really interesting and represents one of the best explanations of the Smith Chart that I have seen.
One quibble: In the beginning, they make it sound like all refelcted power in a transmission line is lost. That is not really true. Much depends on the frequency, the type of line used and the length of the line. The video presents this "SWR loss" as being very significant, and many hams seem to think that any SWR worse than 1:1 will kill their signal.
Look at the question that I put to Gemini:
I am a radio amateur. My SWR meter shows an SWR of 2:1. I am using 50 feet of RG-58 coax to a dipole antenna. The dipole is cut for 40 meters and I am operating on 40 meters. My rig is putting out 100 watts. How many watts are being reflected? How many watts are being radiated?
Gemini calculated:
Assuming your SWR meter is located at the transmitter and shows exactly 100 watts of forward power, 11.1 watts are being reflected at the meter, and approximately 76.1 watts are actually being radiated by your 40-meter dipole.
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That means that in this scenario, I am putting into the transmission line 100 watts and 76.1 watts are being radiated. That means that the loss resulting from this SWR of 2:1 will be about 1.186 db. With one S unit equaling about 6 db, this is clearly not enough to worry about.
Also, lets remember that we could put a 50 ohm dummy load at the far end of our transmission line and achieve an SWR of 1:1. But that dummy load would not radiate.
Three cheers for Veritasium for doing this Smith chart video.
Thanks to Rogier PA1ZZ and to Mike WN2A for sending this video to me.
Please put below your comments on the video and my observations.
First, kudos to this fellow for pronouncing "solder" correctly. The L is silent (sorry to our British readers). He does have an accent, but he is in Texas, and has picked up the CORRECT pronunciation. So kudos.
I really liked the video. It represents a movement into the modern age of electronics. I know that we usually talk about HDR, and homebrew rigs that -- while solid state -- are from the early 1970s. There has been a lot of progress since that time. This video is a reminder of that, and talks about what we can do to participate in this modernity.
Some observations:
-- The microscope. Looks cool, but it is kind of scary...
-- The tiny digital rechargeable soldering iron looks like a great idea.
-- I agree on the mechanical (non chemical) soldering tip cleaner idea.
-- The 3D printer info is very useful.
-- Enclosures? I am still in the 1/8 inch plywood era. I have a ways to go.
-- We could use more info on CNCs.
-- I didn't know that you could get a pick-and-place machine for the home. Probably just as well!
-- I like the thermal camera. I also like his suggestion that you could just burn your fingers!
-- I think an oscilloscpe is a must, even early on. I agree on the need for a multimeter.
Denton E. Nelson (amateur radio callsign W7UHF) was an electronics engineer and a notable figure in mid-century amateur radio history, best known for co-founding Parks Electronics alongside fellow operator Loren Parks (K7AAD) [3.1.3].
Tektronix Background
Nelson spent part of his career in the 1950s working at Tektronix in Oregon, where he moved through various roles from assembly into test and production engineering [1.2.2, 3.2.3]. During his time there, he was also an active member of the Tektronix Employees Radio Amateur Club [3.1.2].
Parks Electronics and VHF Converters
In the 1960s, Nelson (W7UHF) and Parks (K7AAD) partnered to build high-performance VHF (Very High Frequency) converters, initially starting their production in Parks's garage [3.1.3]. At the time, amateur radio operators who wanted to operate on the VHF or UHF bands often relied on outboard converters to shift those higher frequencies down so they could be tuned on standard shortwave communication receivers.
Leveraging their rigorous professional backgrounds at Tektronix, Nelson and Parks applied strict commercial test-equipment standards to their amateur gear [3.1.3]. Parks Electronics quickly became famous for its superior "little black boxes" [3.1.3]. Unlike much of the consumer equipment of the era, every converter Nelson and Parks produced was individually tested for precise gain, bandwidth, and low noise figure before it was shipped [3.1.3]. This commitment to quality made their equipment highly sought after by VHF and UHF enthusiasts worldwide [3.1.3, 4.1.6].
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One question about W7UHF: If you go to QRZ.com, you will see that there is still a listing for W7UHF, under the name of Denton E. Nelson. But it is for a Technician license. And it lists a previous call as KD6EFF. Who is that? Could that be OM Nelson's son? The holder is in Silicon Valley, and the license seems like it is about to expire.
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Loren Parks (1926–2023), who operated under the amateur radio callsign K7AAD, was a man of three distinct legacies: he was a skilled electronics engineer who built highly respected amateur radio gear, and a pioneering manufacturer who made millions in the medical device industry. [3.1.1, 3.1.6].
Tektronix and Amateur Radio (K7AAD)
After serving in the U.S. Navy and earning a degree in psychology, Parks moved to Oregon and took a job in the 1950s with Tektronix, the pioneering test equipment manufacturer [3.1.1, 3.1.6]. He was heavily involved in the local amateur radio scene and the company's ham radio club [3.2.1].
Recognizing that operators needed better ways to tune into the VHF and UHF bands, Parks partnered with his Tektronix colleague Denton Nelson (W7UHF) to build outboard receiving equipment [3.2.2]. What started as a garage project became Parks Electronics [3.2.2]. By applying rigorous commercial test-equipment standards to their amateur gear, their VHF converters became famous for their high performance and exceptionally low noise figures. Parks was also a dedicated supporter of the wider ham community, at one point stepping in to purchase and run the VHF'er magazine to ensure the publication survived [2.3.2, 3.2.2].
The Medical Device Fortune
While his amateur radio converters were a critical success among hobbyists, Parks found his vast fortune in the medical field. In 1961, he founded Parks Medical Electronics in Aloha, Oregon [3.1.1, 3.1.7].
Pivoting his electronics expertise, Parks designed some of the world's first impedance plethysmographs and Doppler ultrasound systems [3.1.1, 3.1.7]. These devices are used by doctors to measure blood flow in vascular studies, detect faint pulses, and monitor patients during surgery [3.1.1, 3.1.5]. His company became a global pioneer in vascular diagnostics—making Parks a multi-millionaire in the process—and it remains one of the oldest manufacturers of Doppler systems in the world today [3.1.5, 3.1.7].
Asianometry always does a great job with this stuff, although I find myself grimacing when he speaks positively about Sarnoff. Nevertheless the tube history is good (although he fails to mention that De Forest never figured out how his tubes worked).
I have four Nuvistors! They are in a 2 meter converter from Parks Electronics of BEAVERTON, OREGON. I may have this wrong, but I think the video said the Nuvistors were very expensive. This can't be right. Gemini AI says the 6CW4s in my Parks device sold for $1.50 to $2.50 in 1961.
Three cheers for the Nuvistor! I may try to see if they still work.
Now we report on a more recent effort by Nakamura, this one is focused on nuclear fusion.
I think the inspirational thing about the Nakamura stories has to do with his persistence, his refusal to give up, and -- in this most recent story -- his willingness to take on big challenges at age 72.
Shuji Nakamura already transformed the world once. His invention of blue light-emitting diodes (LEDs) changed everything about our daily lives.
Computers, phones, big screens, traffic lights and electronic billboards light up because of his invention.
Nakamura earned the Nobel Prize in Physics in 2014, along with two other Japanese scientists, Isamu Akasaki and Hiroshi Amano, for their contributions to his LED breakthrough.
Some experts have hailed his invention as important as Thomas Edison’s incandescent light bulb.
And so, it’s big news when one of the world’s greatest inventors says his next invention will far surpass the importance of his previous one.
His goal: To create a power plant that uses a new kind of high-pulse laser for nuclear fusion, producing an “endless” supply of efficient, clean energy. With nuclear fusion, there is no uranium involved and no chance for a meltdown.
If he cracks the code, its potential is limitless, said Nakamura, a professor of materials and of electrical and computer engineering at the University of California, Santa Barara (UCSB).
At an age when many look to retire, Nakamura, 72, bursts with energy.
“Retirement is very boring,” he told CNN.
‘I became so desperate’
Long before Nakamura earned Nobel recognition, before he was inducted into the National Inventors Hall of Fame, he was maligned and ridiculed — an engineer best known for explosions in his lab and for his lack of productivity.
Nakamura worked at a then-little known Japanese chemical company called Nichia Corporation, in 1979, heading its research and development team, comprised of just two people.
But after about 10 years in, he’d developed only three products — and none sold well. At company soccer and softball games, his colleagues harangued him saying, “Why haven’t you produced anything? You need to quit!”
Afterward, on Friday nights, Nakamura often returned to the office and roamed the halls taking on extra duty as an overnight security guard.
“Yeah,” Nakamura said with a laugh, “I had to check the whole company walking around.”
Feeling isolated, Nakamura developed a mentality of what he calls “invention by anger,” an extreme drive to prove others wrong. All his managers told him the same thing: You must quit.
“I became so desperate,” he said.
A last-ditch effort to save his job
Nakamura grew up in a small Japanese fishing village where he learned to love nature and the color blue because of the ocean.
His experience tinkering, toiling and blowing up stuff in his lab had given him the idea to chase his dream of cracking the code to blue LEDs.Major corporations like IBM, General Electric, Bell Labs, Sony and Toshiba invested millions over the decades trying to solve the mystery. Red and green LEDs were easily mastered, yet the solution to making blue LEDs remained elusive because blue light has a shorter wavelength and requires significantly more energy to emit.
At stake was the potential for a multibillion-dollar industry.
In a last-ditch effort to save his job, Nakamura approached Nichia’s founder and chairman Nobuo Ogawa.
“Can I develop blue LEDs?” Nakamura asked.
He couldn’t believe what came next.
“OK, no problem,” Ogawa said.
Nakamura was given a budget of $3 million, an unheard-of amount in 1988 that represented 2% of the company’s annual sales. Two-thirds of the money was for equipment; the rest was to be spent on studying and learning techniques that could lead to a breakthrough.
‘I feel resentful when people look down on me’
Nakamura then spent a year in a lab at the University of Florida learning about metal-organic chemical vapor deposition, or MOCVD.
At 34, he’d never stepped foot on a plane. He also never had a scientific paper published — a fact that earned scorn in Florida. To those with PhDs in the lab, Nakamura was a nobody with zero academic chops. They treated him like a lowly technician, he said, constantly asking him to fix this and fix that.
He quietly raged. “I feel resentful when people look down on me,” he once said. “At that time, I developed more fighting spirit. I would not allow myself to be beaten by such people.”
Nakamura is a professor of materials and of electrical and computer engineering at the University of California, Santa Barbara. At 72, he has no plans to retire because he feels he's on the verge of his biggest breakthrough to date.
Matt Perko/Univ. of Calif.-Santa Barbara
When he returned to Japan in 1989, more hurdles were thrown his way. His biggest fan, the founder of Nichia, stepped aside as president.
And in his pursuit of a breakthrough, Nakamura chose to go all-in on studying the material gallium nitride as the key to unlocking blue LEDs. Almost every other researcher in the world worked with a different material, zinc selenide.
This became a huge problem, he said, when a renowned researcher held a seminar at Nichia with an emphatic message: gallium nitride was a dead end. Among those in the audience was Nakamura’s new boss.
By day’s end, a hand-written note arrived on his desk, ordering Nakamura to halt all work.
He rejected the order. “I threw it away in the garbage,” he told CNN, smiling.
More notes arrived every few weeks with the same order. He tossed them in the trash, too.
In Japanese culture, he said, it is nearly unheard of to ignore a superior’s orders. In fact, Nakamura stopped attending weekly R&D briefings so that he wouldn’t have to tell colleagues what he was doing.
“I became so angry,” he said, “so that I make the decision” to keep going and keep chasing his dream.
Within months, Nakamura was vindicated. He experienced “the greatest moment of my life,” when he made a simple LED that illuminated with a soft violet-blue light. He wasn’t sure how long the light might last.
He left for the night, and, in the morning, the light still glowed. “It was still very dim, but it’s surviving,” he said. “That moment is very ‘Oh my gosh!’”
On November 29, 1993, Nichia held a news conference that shocked the electronics world. The blue LED had been conquered.
It turned out Nakamura was right: Gallium nitride proved to be the key.
“The tamer of nature and successor to Edison,” Forbes magazine once wrote, “turned out to be an unknown researcher at a Japanese company few had heard of.”
Endless energy as his final chapter
Nichia and Nakamura eventually had a public falling out with back-and-forth lawsuits. The two sides settled their landmark dispute in 2005 — with Nichia agreeing to pay him $8.1 million, far less than the nearly $180 million a Japanese court had ruled Nakamura deserved for his invention.
Almost all of the money, he said, went to “attorney fees and also taxes.”
He prefers not to dwell on that part of his past. He’s proud of what he invented. Plus, he said, “Winning the Nobel Prize was greater.”
“I’m very happy,” he said.
Nichiadidn’t respond to CNN’s request for comment.
A recent report by the International Atomic Energy found that if old light bulbs were still used around the world, global electricity needs would be nearly unsustainable — “around 70% higher electricity consumption for indoor lighting in buildings.” The electricity saved on home lighting from LEDs, the report found, roughly equals the power used by the entire country of South Korea.
Nakamura is focused on the future and what he feels will have an even greater environmental impact by producing limitless energy with zero emissions.
To meet this goal, he has formed Blue Laser Fusion, a company that uses his blue LED technology to create laser power that could transform energy generation around the world.
About 99.5% of nuclear fusion research over the decades, he estimated, has focused on using powerful magnetic fields to create endless power. Nakamura believes the answer lies in the 0.5%.
“The story is very similar to the blue LED development,” Nakamura said.
In December 2022, researchers at the National Ignition Facility at Lawrence Livermore Lab in California, a core part of the US Department of Energy (DOE), achieved the first-ever “fusion gain,” a major scientific breakthrough, when a laser-induced reaction produced more energy than it takes to trigger it.
Nakamura was not involved in that experiment. However, he had already begun developing a new high-power laser concept for inertial fusion, drawing upon his pioneering work in LEDs and laser diodes.
He co-founded Blue Laser Fusion in November 2022. The DOE fusion breakthrough further energized him. Nakamura is determined to take what was proven as scientifically possible in the lab and turn it into a functioning power plant.
He said Blue Laser Fusion has seen breakthrough after breakthrough in the years since.
To contain the continuous fusion reaction without burning everything up,Nakamura and his team have created what is called the optical enhancement cavity, which stores the high-pulse laser energy in its optical chamber, then amplifies the laser power by up to 100,000 times, which drives and contains the burn.
“In layman’s terms,” UCSB said in a 2025 news release, “the laser is the hammer breaking into a tiny pellet of hydrogen isotopes (atoms). The chamber is the anvil, keeping everything contained. The result? Genuinely clean, secure fusion energy.”
At this point, it’s far from Nakamura’s goal of limitless energy with far-reaching benefits.
More work is needed. The company is scaling up to meet its goal to construct a 1-gigawatt pilot fusion power plant — big enough to power 750,000 to 1 million homes — by 2032 near Santa Barbara, California.
Will this be his greatest achievement and gift to the world?
“Yeah, yeah,” Nakamura said simply.
Asked how he might react if a young scientist in his lab defies his orders and continues doing whatever he or she wants to do, Nakamura laughed.
His message to young scientists everywhere, he said, is this: “Taking a risk is most important.”
L to R: Farhan, Roy Lewallen, Eric Guth and Hans Summers
Back in 2018, I remember Farhan telling me that "Hans has cracked the code" getting stable I and Q from the Si5351. But I never really appreciated the importance of this breakthough until I recently started looking at the receiver from Macedonia. Then I asked AI (Google Gemini) for a readout on who was responsible for the I and Q innovation. Here is what I got yesterday from Gemini:
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The credit for solving this problem and unlocking stable, single-chip I/Q quadrature generation from the Si5351 goes to Hans Summers, the British QRP developer and founder of QRP Labs.
While other talented developers in the amateur radio community—most notably Jason Mildrum (NT7S)—wrote the definitive, widely used standard open-source Arduino libraries for basic Si5351 tuning, it was Hans Summers who fundamentally cracked the math required to force the chip into a stable 90 degree phase shift over a wide frequency range without breaking lock.
The Breakthrough Discovery
Around 2014 to 2015, while designing highly compact, low-cost transceivers like the QCX and ultimate VFO kits, Summers realized that standard programming libraries were completely incompatible with generating stable quadrature signals.
He pioneered a completely reversed architectural method to control the chip, which became the blueprint for homebrew SDR builders everywhere:
Flipping the Fractional Math: Standard libraries fixed the primary internal Voltage Controlled Oscillator (VCO/PLL) at an integer value and used the second stage (the MultiSynth fractional dividers) to dial in the exact frequency. Summers realized this broke the phase shift. He discovered that you must lock the MultiSynth divider to a fixed even integer and force the first stage (the PLL VCO) to do the fractional math instead.
The "No Reset" Discovery: Standard practices issued a soft PLL reset command to the chip every time the user turned the tuning dial to ensure clean frequencies. This reset caused the phase relationship to drop out or randomize. Summers proved that after an initial startup reset to align the phases, you can smoothly glide the VCO frequency up and down via the I2C bus without resetting the PLL, keeping the I and Q signals locked in a perfect mathematical embrace.
Thanks to Hans Summers publishing his detailed engineering application notes and open-sourcing his mathematical methods, developers around the world were able to write the code that modern microcontrollers (like the ESP32 in your receiver) use today to keep the I/Q phase rock-solid as you dial across the bands.
