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I receive very little feedback overall on RF Cafe content. Surprisingly, though, the 'Day in History' feature on the homepage generates the most e-mails either due to a typo by me or someone commenting on a particular item. It's nice to know they're read. Website visitor Steve Gilbert just wrote regarding Oldsmobile founder Ransom E. Olds' entry from August 26. Says Steve, "Ransom Olds was born just a few blocks away from where your friends at Tegam have their business located in Geneva, Ohio. Fittingly the site of Ransom Olds' birthplace is today an auto parts store." A quick Google search turned up a historical marker located on Old's property, and it gave the GPS coordinates. Plugging those into Google Maps placed me right at the spot, and then a Street View ...
Manmade electrical noise (QRM) and natural electrical noise (QRN) has been the nemesis of communications - both wired and wireless - since the first signals were sent. While it is true that over the last century the amount of 'background' noise has increased significantly, the ability of modern circuits to deal with (reject) it and/or accommodate (error correction) it has pretty much kept up with the advancement. You might be tempted to think that 'back in the good old days' such problems did not exist, but operators were plagued by poorly designed and inadequately filtered transmitters as well as really deficient electrical service installation that spewed noise from transformers, inadequately grounded transmission lines, lousy connections, ...
month I randomly select one or two people from my e-mail inbox who are entered for the
FREE book drawing (I pay the shipping
cost from my ever-thinning
To date I have shipped over 120 books that are typically valued at over $100 each; all are recently released volumes
by top engineering publishers like Artech House
and Cambridge University Press. These two titles
have been added for the September drawing:
- RF Positioning: Fundamentals,
Applications, and Tools (GNSS
Technology and Applications)
- The Art and Science of
Just as the test and measurement equipment manufactures scrambled to produce lines of spectrum, network and communications analyzers, oscilloscopes, power meters, electromagnetic field sensors, and many other types of products specifically for the cellphone and Wi-Fi industries, companies were scrambling to provide for the needs of FM radio and television development labs and production lines. This 1947 advertisement from Radio Corporation of America (RCA) is an example that appeared in Radio News magazine. In fact, TV was so new that just a few months later, in September of 1948, editor Hugo Gernsback changed the publication's name to . BTW, did you even know RCA made ...
Don't let the title fool you. This 'Ultrafax' system developed by RCA in the late 1940s was essentially the first attempt at video on demand, or streaming video. Rather than piping the signal over cable or local broadcast frequency towers, a microwave link was used. While initial system equipment space and financial requirements meant only corporations, universities, and governments could procure an Ultrafax, engineers who developed the system envisioned an eventual culmination of equivalent systems in every home. Even at the end of the last century it was still not possible for program providers to personalize broadcasts to individuals. It wasn't until broadband Internet came on the scene in the 2000s that such services were possible. Now, a decade later, people watch any video they want on cellphones while riding in a car ...
Mechanically generated electrical noise has been the bane of wireless communications since the days of Marconi. I recently posted a 1930 article from Radio-Craft titled "More About 'Man-Made' Static" that addressed the plague. Electrical noise adversely affects electronics in a manner ranging from relatively harmless but annoying interference to destructive discharging. We are very familiar with ESD and the hazard it presents to electronic devices. Triboelectric charging and a subsequent rapid discharge is the culprit. Much research has led to ingenuous mitigation and prevention techniques that have practically eliminated the problem. Still, electrical noise crops up in some of the most unexpected places and must be dealt with. An article dealing with triboelectric charging and static discharge in radio controlled (R/C) helicopters, with the resultant radio interference ...
At least for now, I am going to only scan and post schematics & parts lists like the ones listed below, rather than use OCR (optical character recognition) software on them to separate the textual content. There are still many people who restore and service these vintage radios, and often it can be difficult or impossible to find schematics and/or tuning information. I will keep a running list of all data sheets to facilitate a search.
- RCA Victor Portable Table
- Atwater Kent Model 305Z 5-Tube
32 V. D.C. Superhet
- Kadette Jewel Model 40 Chassis
3-Tube Ultra-Midget Receivers
Models 41, 43, 44 and 48
- General Electric Model N-60 6-Tube
You can buy a pretty good metal detector today for a hundred dollars that will find coins buried many inches deep and larger metallic items even deeper, and you even get discriminator functions to filter out unwanted objects like tin cans. They weigh just a couple pounds and can be used with one arm. Compare that to early metal detectors that had huge induction coils on a frame so heavy that shoulder straps were needed just to lug them around. Some models came on wheels for pushing or pulling like a cart. You could plan to spend a few hundred dollars (a thousand or more in today's dollars) for one. Even then, they were not as sophisticated as the $50 models sold in Walmart now. In classic fashion, teen electronics hobbyists Carl and Jerry use their technical prowess to design and build their own metal detector and then unintentionally using it to convince ...
A lot of people like to demean engineers and scientists for their propensity to want to conduct experiments and obtain measured, empirical data rather than 'winging it' and being satisfied with 'intuitive' knowledge or the contemporarily popular term 'gut.' If mankind had not adopted scientific methods and ventured beyond the 'cradle of civilization' on the African continent, we would all still be living in grass huts, hurling rocks at prey, and foraging for berries. Quantifying and categorizing all things in nature helps inventors create new and improved implements that help make life better. Early on it was mostly individuals like Archimedes, Euler, Newton, and Edison who built the pool of knowledge that fed and evolved into corporations, governments, and universities doing the vast majority of the work. Bell Laboratories is probably one of ...
Linx Technologies, a Merlin, OR based developer and manufacturer of Internet of Things (IoT) Products and Solutions, is pleased to introduce its new pre-certified, low cost RF data modules. The HumPRO™ Series transceiver is built on the popular Hummingbird platform, and is a frequency hopping spread spectrum (FHSS) transceiver designed for the reliable transfer of digital data. Available today in 900 MHz, the HumPRO™ 900 MHz version outputs up to 10 dBm. This results in a line-of-sight range of up to 1600 m (1.0 mile). The HumPRO™ Series module is a completely integrated RF transceiver and processor designed to transmit digital data across a wireless link. It employs a fast-locking FHSS system for noise immunity and higher transmitter output power as allowed by government regulations ...
Fairview Microwave, a supplier of on-demand microwave and RF components, introduces their new family of precision waveguide directional couplers. This release consists of 28 models covering a frequency range from 18 GHz to 110 GHz in seven popular frequency bands including K, Ka, Q, U, V, E and W bands. Fairview Microwave's waveguide couplers are available in waveguide sizes from WR-42 up to 18 GHz all the way to WR-10 up to 110 GHz. These directional couplers are offered with 10 dB or 20 dB coupling values and have high directivity of 30 dB typical with insertion loss is as low as 0.6 dB in certain models. Fairview’s new waveguide couplers are available in both standard and split block configurations and are also available in both E-Bend and H-Bend designs. They utilize a multi-hole ...
United States Patent 9,093,731 B2, recently awarded to Empower RF Systems, validates the uniqueness of the hardware architecture in use on Empower's high power, next generation amplifiers. The embodiments of this patent protection are related to the design, associated materials, and integration of the high power combiner that is integral to delivering multi-kW broadband power (CW) and narrow band pulse in an air cooled, 5U chassis (and other combinations of power and chassis sizes utilizing this architecture). "We are pleased to receive this additional recognition and patent protection for our next generation amplifiers," said Jon Jacocks, CEO. "This is a second award this year that is specific to our next ...
WiSilica, the smart environment enabler creating a more intelligent IoT, has launched an end-to-end solution for connecting millions of devices that can understand their environment and use predictive intelligence to improve the user experience, reduce cost and improve efficiency. Taking advantage of the existing smartphone ecosystem and WiSilica's proprietary mesh networking technology, the WiSe platform enables customers to easily configure smart homes, buildings, lighting, sensors and wearables into intelligent devices that they can manage via mobile apps and in the cloud. "WiSilica provides customers with the building blocks and framework to create complete smart IoT environments," ...
MECA is pleased to announce the addition to our 662 series, 2 watt SMA attenuators operating now up to 6 GHz! The 662-dB-1F6 series attenuators cover all wireless applications from Hz – 6.0 GHz and available in standard values of 3, 6, 10, 20 & 30 dB. And as always made is USA carrying MECA's 36 month warranty ...