Homepage Archive - March 2019 (page 2)

These archive pages are provided in order to make it easier for you to find items that you remember seeing on the RF Cafe homepage. Of course probably the easiest way to find anything on the website is to use the "Search RF Cafe" box at the top of every page. About RF Cafe.

Homepage Archive Pages

2024:  Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec

2023:  Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec

2022:  Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec

2021:  Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec

2020:  Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec

2019:  Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec

2018:  Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec

2017:  Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec

2016:  Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec

2015:  Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec

2014:  Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec

2013:  Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec

2012:  1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 (no archives before 2012)


See Page 1 | 2 | 3 | 4  of the March 2019 homepage archives.
col-width

Friday 15

New Technology Sparks an Expansion for Germanium Transistors

New Technology Sparks an Expansion for Germanium Transistors, April 6, 1964 Electronics Magazine - RF CafeWhilst reading articles on semiconductor research and development in the era of this 1964 Electronics magazine, it often occurs to me that much of the terminology presented is new to most people in the electronics field, having been just recently coined by those developing the technology. To wit, here author Landress shows diagrams of planar and mesa structures for transistors. We are so familiar by now with those configurations that it hardly seems there was a time when engineers did not speak so matter-of-factly of them. Hole and electron mobilities were terms familiar to a niche group of atomic materials scientists a decade earlier, as were diffusion depth and doping concentrations. As the 1919 electronics practitioner would confabulate upon matters of thermionic emission and getter flashing in vacuum tubes ...

PEI-Genesis Connectors & Cable Assemblies

PEI-Genesis Cables & Connectors - RF CafePEI-Genesis is a global leader in the design and assembly of custom engineered connectors and cable solutions for harsh environments. PEI develops custom interconnect solutions that support the harsh environments of the aviation, energy, military, industrial, rail, and medical sectors worldwide. Proprietary automation in mirrored factories around the world allows PEI to assemble, from one of the largest inventories of electronic components, according to customers' specific requirements. PEI-Genesis has been listed on the related Vendors listing pages. Free shipping for orders >$40 ...

Withwave Intros VNA Automatic Calibration Module

Withwave Intros VNA Automatic Calibration Module - RF CafeWithwave's Automatic Calibration Module (W1202A) is ideal for users who want fast and easy calibration for various Vector Network Analyzers (VNA). This module is powered up via USB or F5.5 DC connector and communicate with VNA via USB or LAN and designed for full one-port through two-port calibrations of VNAs by One-Push START button. This module works as host systems, measures and calculates calibration coefficients and sends it to VNA easily. Most of Electronic Calibration Kits work for same manufacturer's VNAs only. But, this module provides cost-effective calibration solution for users by supporting various VNA models: Keysight PNA & ENA series, R&S ZVL, ZVA & ZVT series, Anritsu ShockLine Series ...

1000s of Semiconductor Nuclei 'Quantum Dance' in Unison

Thousands of Semiconductor Nuclei 'Quantum Dance' in Unison - RF Cafe"A team of Cambridge researchers have found a way to control the sea of nuclei in semiconductor quantum dots so they can operate as a quantum memory device. Quantum dots are crystals made up of thousands of atoms, and each of these atoms interacts magnetically with the trapped electron. If left alone to its own devices, this interaction of the electron with the nuclear spins, limits the usefulness of the electron as a quantum bit - a qubit. Led by Professor Mete Atature, a Fellow at St John's College, University of Cambridge, the research group, located at the Cavendish Labor ..."

Associate Layout Engineer Needed by QuinStar Technology

Associate Layout Engineer Needed by QuinStar Technology - RF CafeQuinstar Technology, an AS9100 certified aerospace hardware design and manufacturing company in Torrance, CA, is currently looking for an Associate Layout Engineer to join our team! We are primarily Looking for a highly motivated quick learner with a bachelor of science degree in electrical engineering or equivalent industry experience who is a US citizen. Should have experience creating hybrid RF circuit assembly drawings using AutoCAD or equivalent, drafting mechanical drawings, and/or using Vee test software is desired! Preference given to candidates with related experience. Primary job responsibilities include supporting MMIC design/development, reviewing engineering MMIC layouts ...

Empower RF Systems: RF & Microwave Power Amplifiers

Empower RF SystemsEmpower RF Systems is a global leader in power amplifier solutions. Empower RF Systems is an established and technologically superior supplier of high power solid state RF & microwave amplifiers. Our offerings include modules, intelligent rack-mount amplifiers, and multi-function RF Power Amplifier solutions to 6 GHz in broadband and band specific designs. Output power combinations range from tens of watts to multi-kilowatts. Unprecedented size, weight and power reduction of our amplifiers is superior to anything in the market at similar frequencies and power levels ...

Thursday 14

ConductRF Flexible & Hand Formable Solutions

ConductRF Precision D38999 RF & Mixed Signal Cables - RF CafeConductRF offers an extensive line of RF and mixed signal cable harnesses and assemblies with custom configurations, lengths and markings. Thousands of combinations of coaxial, power, and digital and analog signal connectors available. Flexible phase-stable, low-loss, phase-matching, high power, and other options per your requirements. Broad insert connector solution choices including BMA, SMPM, for cable sizes #8, #12 & #16 Custom marking and ruggedization enhancements capability. Contact ConductRF today and let us help your project ...

Notable Quote: Wernher von Braun

Wernher Magnus Maximilian, Freiherr von Braun - RF CafeWernher Magnus Maximilian, Freiherr von Braun, chief designer of the V−2 rocket that terrorized London in the 1940s and chief architect of the Saturn V rocket that launched the first men to the moon in the 1960s, is quoted as saying, "The best computer is a man, and it's the only one that can be mass-produced by unskilled labor." von Braun was one of many German scientists conscripted to do the National Socialist German Workers Party (aka Nazi) regime's bidding during World War II - formally an Schutzstaffel (aka SS) officer. He and his research team surrendered to the Americans in 1945 after escaping to Austria when the end of the Third Reich was imminent. His willingness to be part of the Nazi German war effort is fuzzy; therefore, I have a hard time fully appreciating his significant contributions to the U.S. space program. Reportedly, von Braun experienced a genuine Christian religious conversion that changed his life.

How Spread Spectrum Radio Control Systems Came to Be

How Digital Spread Spectrum Radio Control Systems Came to Be - Airplanes and RocketsThe March 2019 issue of the Academy of Model Aeronautics' Model Aviation magazine contains a letter from Dave Jones, of the AUAV website. Mr. Jones informs us that, contrary to popular belief, he was the designer, builder, and tester of the first frequency hopping spread spectrum (FHSS) radio control system (R/C) operating in the 2.4 GHz ISM band. He developed his system for the DoD back in the 1990s, many years before Spektrum R/C marketed its first commercial spread spectrum system in the early 2000s (see my Spektrum DX6 teardown). Prior to 2.4 GHz systems (now a combo of FHSS and DSSS), FM and to a lesser extent AM digital proportional R/C systems were primarily on the 72 (air, 50 channels) / 75 (surface, 30 channels) MHz band (a few on 50/53 MHz for licensed Hams). RF interference and unintentional "stepping on" frequencies in use often resulted in costly aircraft crashes. The 72 Hz systems were vulnerable to metal-to-metal noise (a problem in helicopters) whereas the 2.4 GHz systems are immune. Dave Jones made a Monkee of that issue and sent it to the bottom of the sea, figuratively speaking. And now you know... the rest of the story.

Design PCBs for EMI: How Signals Move

Design PCBs for EMI: How Signals Move - RF CafeKenneth Wyatt has an article on the EDN website titled, "Design PCBs for EMI, Part 1: How Signals Move," that should be useful to anyone looking for tips on the subject. Says Kenneth, "After helping clients get their products compliant for EMI, I've seen one underlying issue: Poor PC board design. In my experience, IoT product designers run into problems caused by poor PC board design. Poor design can cause endless delays when on-board energy sources disrupt sensitive receiver circuits, resulting in cellular compliance failures. GPS and Wi-Fi receivers can also lose sensitivity ..."

Smiths Interconnect Looking for an RF Test Technician

Smiths Interconnect Looking for an RF Test Technician - RF CafeSmiths Interconnect currently has a job opportunity for an RF Test Technician. Smiths is always looking for curious minds. For new colleagues who want responsibility and relish a challenge. Those who would like to use their talents to help make the world safer, healthier, more efficient and more connected. Job Description: To test and troubleshoot Smiths Interconnect products to ensure high quality. Duties & Responsibilities: Solid understanding of electronic and microwave test equipment including VNAs, signal generators, power amplifiers, pulse generators, o-scopes, multimeters and associated hand tools. Ability to assemble RF test fixtures and burn-in test fixtures, troubleshoot RF test fixtures and test setups, documentation of test procedures ...

NASA to Demonstrate X-Ray Based Space Communications Technology

NASA to Demonstrate X-Ray Based Space Communications Technology - RF Cafe"NASA is set to demonstrate a new experimental type of deep space communications technology on the ISS this spring. Currently, NASA relies on radio waves to send information between the spacecraft and Earth. Emerging laser communications technology offers higher data rates that let spacecraft transmit more data at a time. This demonstration involves X-ray communications, or XCOM, which has numerous advantages. X-rays have much shorter wavelengths than both infrared and radio. This means that, in principle, XCOM can send more data for the same amount of transmission power. The X-rays can broadcast in tighter beams, thus using less energy when communicating over vast distances. If successful, the experiment ..."

Anatech Electronics: Off-the-Shelf and Custom RF & Microwave Filters

Anatech Electronics logo - RF CafeAnatech Electronics (AEI) manufactures and supplies RF and microwave filters for military and commercial communication systems, providing standard LP, HP, BP, BS, notch, diplexer, and custom RF filters, and RF products. Standard RF filter and cable assembly products are published in our website database for ease of procurement. Custom RF filters designs are used when a standard cannot be found, or the requirements dictate a custom approach. Sam Benzacar's monthly newsletters address contemporary wireless subjects. Please visit Anatech today to see how they can help your project succeed ... 

Wednesday 13

Delco Radio Division of General Motors Employment Ad

Delco Radio Division of General Motors Employment Advertisement, March 6, 1964 Electronics Magazine - RF CafeI, along with probably most other people my age, habitually associate the brand name of Delco (Delco Electronics, technically) with General Motors (GM) electrical and electronic products such as radios, storage batteries, alternators, and spark plugs. Dayton Engineering Laboratories Co., of Dayton, Ohio, merged with GM's AC spark plug division in 1974 to become AC-Delco. I bought many sets of AC-Delco spark plugs for my cars over the years. Nowadays, GM's electronic products go by the name of ACDelco (no hyphen now). Attempting to research the full provenance of the modern-day AC-Delco is headache-inducing due to sell-offs to Delphi, Aptiv, and other entities. The best I can determine is that the contemporary ACDelco is a brand name for products that might be manufactured by many different companies. This advertisement searching for electrical and mechanical engineers ...

Axiom TE Blog: Learn More About Electronic Loads

Axiom Test Equipment Blog: Learn More About Electronic Loads - RF CafeAxiom Test Equipment, an electronic test equipment rentals and sales company, has published a blog post explaining how to source the right electronic load for your next project. Engineers working with power circuitry can use this post as a guide towards what specifications are important to know when selecting a load. The post goes over AC loads, DC loads, combination AC/DC loads, and whether the load will be used for manual or automatic measurements, for testing one circuit or unit under test at a time or multiple units under test. Reliable, high-performance DC and AC electronic loads are available from several manufacturers and are typically characterized as low, medium, and high-power loads. Mainframes with interchangeable modules to customize ...

R&S 15-Minute Tutorial: Understanding TOI Measurements

R&S 15-Minute Tutorial: Understanding TOI Measurements - RF CafeRohde & Schwarz has produced a 15-minute tutorial titled, "Understanding 3rd-Order Intercept Measurements." In Amplifier design, Third Order Intercept (TOI) is the most common measurement of the devices linearity. This tutorial explains the fundamentals of Third Order Intercept. It will include how to measure it and where the pitfalls are so you become aware during your testing. It's a short 15-minute tutorial so you get what you need quickly and can continue on with your busy day. You will learn about linearity, harmonics, higher order products and inter modulation products. We will also cover measurement considerations, test configurations and what to watch out for ...

Opportunity Awareness: Thoughtful Reflections on Your Future

Opportunity Awareness: Thoughtful Reflections on Your Future, April 1971 Popular Electronics - RF CafeThis 1971 article from Popular Electronics magazine was the twelfth in a long series of features reporting on electronics related college degrees, technical schools, on-the-job training, military training, areas of specialty, career planning and options, current hiring practices and companies doing the hiring, salaries and hourly rates, worker's compensation and insurance, etc. All the issues of importance today were being covered even half a century ago, although the names have been changed for some entities. For instance the state employment bureaus are now referred to as departments of labor and industry; e.g., here in Pennsylvania, the DLI supplies statistics on labor ...

Please Visit Triad RF Systems to Thank Them for Their Support

Triad RF SystemsTriad RF Systems designs and manufactures RF power amplifiers and systems. Triad RF Systems comprises three partners (hence 'Triad') with over 40 years of accumulated knowledge of what is required to design, manufacture, market, sell and service RF/Microwave amplifiers and amplifier systems. PA, LNA, bi-directional, and frequency translating amplifiers are available, in formats including tower mount, benchtop, rack mount, and chassis mount. "We view Triad more as a technology partner than a vendor for our line-of-sight communications product line." Please check to see how we can help your project ... Please check to see how they can help your project ...

The Critical Role OTA Testing Will Play in 5G

The Critical Role OTA Testing Will Play in 5G - RF CafeMaybe once quantum computers and übercomplex physical models of dense urban environments are available for simulation, there won't be a need for in-situ empirical testing of wireless coverage, but at this time the success or failure of impending 5G communications will be dependent on field tests. Of course part of that testing will be receiving service complaints from customers due to systems being activated before they are fully qualified - aka known as the Microsoft product release strategy  ;-(  This article titled, "The Critical Role OTA Testing Will Play in 5G," by Lawrence Wilson, in Microwave & RF magazine touches on the subject ...

Res-Net Microwave: Precision RF & Microwave Components

Res-Net Microwave componentsRes-Net Microwave has a complete line of precision RF & microwave components including attenuators, terminations, resistors, and diode detectors for commercial, military, and space applications. Products range from the small flange type to large 2,000 watt connectorized power attenuators and/or terminations at frequencies up to 26.5 GHz. In-house photo etch and laser trim capability. Please check out Res-Net Microwave's website to see how they can help with your current project ...

Tuesday 12

Saelig Intros Euroquartz SM Highly Stable Oscillators

Saelig Launches Euroquartz Surface-Mount Miniature Highly Stable Oscillators - RF CafeSaelig Company, Inc., has introduced the OC51T series of surface mount miniature oven-controlled crystal oscillators (OCXO) from frequency control specialists Euroquartz. These square-wave frequency sources are housed in a tiny surface-mount package and offer optimal frequency stability from a quartz IT-cut crystal. The OC51T series is available in frequencies from 10 MHz to 40 MHz and comes in a 9.7 x 7.5 x 4.1 mm miniature 4-pad package with 3.3 and 5.0 V supply voltage options. With voltage control as standard, OC51T OCXOs deliver a frequency stability ...

1953 Radio-Electronics Tech-Themed Comic

Electronics-Themed Comics, March 1953 Radio-Electronics - RF CafeIf you look through the hundreds of technology-themed comics that appeared various electronics magazines, many deal with the trials and tribulations of television repair and service. That is because in the introductory era of TVs, people were, understandably, infatuated with being able to not just hear but see what was happening in the broadcast. Radios and phonographs got a lot of coverage as well. Storylines involving a guy on the roof installing or repairing an antenna were considered particularly funny, especially if it depicted someone hanging precariously from a lead-in cable or a ladder rung. This comic addresses the all-too-common situation where sometimes a better picture was obtained using a makeshift antenna than with a bona fide, professionally designed antenna ...

ANSYS : EMI Scanner

ANSYS EMI Scanner - RF CafeANSYS is offering this free whitepaper titled, "EMI Scanner." This capability provides automatic and customizable EMI design rule check of PCBs. EMI Scanner can quickly identify areas of potential interference on your PCB design prior to simulation. EMI issues traditionally have been difficult to simulate and require hours of computational time. This new feature included within ANSYS SIwave and ANSYS HFSS quickly identifies potential trouble spots that require further investigation. It eliminates errors and speeds time to market ...

Astro Pak Chemical Cleaning Services

Astro Pak Metal Cleaning Services - RF CafeAstro Pak on-site and in-plant chemical cleaning services. On-site and in-shop services in precision cleaning, passivation, electropolishing, pickling & passivation, oxygen cleaning, derouging, sanitization & biofilm removal, hydrostatic & pneumatic testing, media blasting, cleanroom services. Same Day emergency service available. Astro Pak has been added to the RF Cafe Metal Preparation & Finishing Products & Services webpage.

Vintage Watkins-Johnson Tech Notes Additions & Updates

Vintage Watkins-Johnson Tech Notes Additions & Updates - RF CafeThanks to Chuck U. for providing new Watkins-Johnson (WJ) Tech Notes v10-3 and v15-2, and an improved copy of v5-2. A lot (but not all) of the TNs that I had or other people sent to me are made from B&W copies from old scanners, so the quality is not super good. Chuck's versions appear to be scanned from the originals in color, so they're very good ...

Please Thank PCB Directory for Supporting RF Cafe

PCB  Directory - RF Cafe

PCB Directory is the largest directory of Printed Circuit Board (PCB) Manufacturers, Assembly houses, and Design Services on the Internet. We have listed the leading printed circuit board manufacturers around the world and made them searchable by their capabilities - Number of laminates used, Board thicknesses supported, Number of layers supported, Types of substrates (e.g., material, flexible, rigid), Geographical location, and more ...

A New Spin in Nano-Electronics

A New Spin in Nano-Electronics - RF Cafe"In recent years, electronic data processing has been evolving in one direction only: The industry has downsized its components to the nanometer range. But this process is now reaching its physical limits. Researchers at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) are therefore exploring spin waves or so-called magnons - a promising alternative for transporting information in more compact microchips. Cooperating with international partners, they have successfully generated and controlled extremely short-wavelength spin waves. The physicists achieved this feat by harnessing a natural magnetic phenomenon, as they explain in the journal Nature Nanotechnology ..."

Monday 11

Many Thanks to ConductRF for Continued Support!

ConductRF coaxial cables & connectors - RF CafeConductRF is continually innovating and developing new and improved solutions for RF Interconnect needs. See the latest TESTeCON RF Test Cables for labs. ConductRF makes production and test coax cable assemblies for amplitude and phased matched VNA applications as well as standard & precision RF connectors. Over 1,000 solutions for low PIM in-building to choose from in the iBwave component library. They also provide custom coax solutions for applications where some standard just won't do. A partnership with Newark assures fast, reliable access. Please visit ConductRF today to see how they can help your project!

5G and the Connected Vehicle

ANSYS 5G and the Connected Vehicle - RF CafeANSYS is offering this free whitepaper titled, "5G and the Connected Vehicle." Combining fully autonomous (AV) technology with 5G-delivered, high-speed and low-latency wireless data promises a safer, more user-friendly driving experience. This impending merger is a result of the developing 5G infrastructure that will provide reliable vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I) and vehicle-to-everything (V2X) connectivity for a variety of new, real-time communication services. The simulation of these connected systems is key to assessing their performance and limits before deployment to ensure maximum performance and reliability ...

Nine of the Latest New Developments from G-E Research

Nine of the Latest New Developments from G-E Research, March 6, 1964 Electronics Magazine - RF CafeHalf a decade after Texas Instruments (Jack Kilby, 1958) and Fairchild Semiconductor (Robert Noyce, 1960) produced the first semiconductor integrated circuits, General Electric must not have been too confident that the newfangled technology was going to take hold. This 2-page spread from a 1964 issue of Electronics magazine, promotes their "Compactron" integrated circuit vacuum tubes. The Compactron is a building block concept where standardized stages of diodes, triodes, pentodes, etc., are encapsulated in a single vacuum tube package with necessary input and output pins for connecting external components. The incentive was smaller volume, lower parts count, lower power supply current, simpler chassis wiring or circuit board layout, and greater ruggedness. One source I found showed the availability in 1962 of 24 distinct Compactron models ...

Daylight Saving(s) Time - Again!

Graphical Look at Daylight Saving(s) Time - RF CafeCall me obsessive, but the switch to and from DST has bugged me not so much for its existence, but for butthead politicians that won't keep their hands off of it. A few years ago I wrote a piece titled, "A Graphical Look at Daylight Saving(s) Time," to deal with it, and then again last year with, "Daylight Saving(s) Time vs. Standard Time." Research the history of DST and you will see how often Congress has changed the days - always for good reasons, don't you know. In 1958, the year of my birth, DST began on April 27th 1958 Old Farmer's Almanac Daylight Savings Time - RF Cafe(vs. March 10th this year), and ended on September 28th (November 3rd this year) - See 1958 Old Farmer's Almanac pages. What else can I say on the matter?

Free Engineering Magazines for March 2019

Engineering White Papers & Books, March 2019 - RF CafeWhitepapers, pamphlets, books, magazines, and chapter examples listed here are a small sample of a lot of new items that are offered for FREE through TradePub. The publishers make them available to qualifying people as a promotional campaign for their full line of offerings. Whitepaper topics include careers, manufacturing, and engineering, while magazine titles include Microwave Engineering Europe, Electronic Design, and Microwave Product Digest. Note: I earn a few pennies (literally) when you download one of these or the many other pubs available, so please help yourself ...

First Carbon-Nanotube Mixed-Signal ICs

First Carbon-Nanotube Mixed-Signal ICs - RF Cafe"All the amazing carbon-nanotube logic circuits we've heard about over the years have a dirty secret: Some of those nanotubes are metallic rather than the semiconducting type that's wanted. This tiny fraction of bad tubes is no big deal for logic circuits. They add a bit of noise, but nothing the digital nature of logic can't deal with. The problem has been analog circuits. For analog, that stray metallic nanotube may as well be basilisk venom. 'A single metallic [carbon nanotube] causes a complete circuit failure in a simple amplifier,' Aya G. Amer explained to engineers at the IEEE International Solid-State Circuits Conference last week in San Francisco ..."

Many Thanks to Axiom Test Equipment for Continued Support!

Axiom Test Equipment - RF CafeAxiom Test Equipment allows you to rent or buy test equipment, repair test equipment, or sell or trade test equipment. They are committed to providing superior customer service and high quality electronic test equipment. Axiom offers customers several practical, efficient, and cost effective solutions for their projects' TE needs and is committed to providing superior customer service and high quality electronic test equipment. Please check out Axiom Test Equipment today! ...

Sunday 10

RF Cafe Engineering & Science Crossword Puzzle for March 10

RF Cafe Engineering & Science Crossword Puzzle March 10, 2019Since 2000, I have been creating custom science-themed crossword puzzles for the brain-exercising benefit and pleasure of RF Cafe visitors who are fellow cruciverbalists. The jury is out on whether or not this type of mental challenge helps keep your gray matter from atrophying in old age, but it certainly helps maintain your vocabulary and cognitive skills at all ages. A database of thousands of words has been built up over the years and contains only clues and terms associated with engineering, science, physical, astronomy, mathematics, chemistry, etc. You will never find a word taxing your knowledge of a numbnut soap opera star or the name of some obscure village in the Andes mountains. You might, however, encounter the name of a movie start like Hedy Lamarr or a geographical location like Tunguska, Russia, for reasons which, if you don't already know, might surprise you ...