I'm not sure how much
mechanical filters are used in circuit design these days due to their somewhat
large size and complexity. They typically exhibit a high "Q" with a relatively flat
passband (with some ripple) and very sharp cutoff in the skirts, and the insertion
loss is low compared to lumped element equivalents (for comparative out-of-band
cutoff). Operational frequencies were limited to a few hundred kilohertz, so they
are useful only at intermediate and baseband frequencies. This article, appeared
in a 1953 issue of Radio-Electronics magazine, describes the basics of mechanical
filter design and construction. Mechanical filters from aircraft radio manufacturer
Collins and other can be found on eBay...
Anatech Electronics offers the industry's
largest portfolio of high-performance standard and customized RF and microwave filters
and filter-related products for military, commercial, aerospace and defense, and
industrial applications up to 40 GHz. The AE915-1380-2745TR1271 is a
ISM, GSM1800, LTE Band combiner. Used to combine all 3 bands into one antenna
or split the bands from an antenna to the system, it features an incredible 100 dB
isolation between the bands, very Low insertion loss, and a power handling of 300 watts.
The AE1200-1400DB5450 features DC-1200 MHz and 1400-3000 MHz bands with
a crossover insertion loss of 5 dB at 1300 MHz. Custom RF power directional
coupler designs can be designed and produced when a standard cannot be found...
"As the semiconductor industry witnesses
the winding down of the expectation that the number of transistors that can be shoehorned
into silicon microchips will double every couple of years, researchers are coming
up with new ways to keep the effect of Moore's Law rolling along. One such method
with exciting prospects employs
liquid metals to produce two-dimensional semiconducting materials with atomic-scale
thickness. This enables the creation of a transistor channel between source and
drain that is almost an order of magnitude thinner than those employed in silicon
transistors. In addition, they possess intriguing properties such as a variety of
band gaps and carrier concentrations, as well as unique transducing properties.
“The two-dimensional confinement of free charge-carriers..."
Prior to the advent of
FET-input multimeters, obtaining a very high input impedance meter required
the use of a vacuum tube circuit that used a buffer stage to isolate the measured
signal from the loading effects of the meter movement. As most people reading this
article already know, the voltage value indicated by a non-buffered meter can be
greatly affected by the meter's loading of the device under test (DUT) if the meter's
impedance is not many times greater than the DUT's impedance. The voltmeter is used
in parallel with the circuit under test, so for example if the impedance of the
DUT is 100 kΩ and the meter's impedance is also 100 kΩ, the meter will
display a value as if the DUT itself had only a 50 kΩ impedance, which represents
a huge error. The problem was that VTVMs were relatively expensive and beyond the
budget of most amateurs...
This assortment of custom-designed themes
by RF Cafe includes T-Shirts, Mouse Pads, Clocks, Tote Bags, Coffee Mugs and Steins,
Purses, Sweatshirts, and Baseball Caps. Choose from amazingly clever "We Are the World's Matchmakers"
Smith chart design or the "Engineer's Troubleshooting Flow Chart." My "Matchmaker's"
design has been ripped off by other people and used on their products, so please
be sure to purchase only official RF Cafe gear. My markup is only a paltry 50¢ per
item - Cafe Press gets the rest of your purchase price. These would make excellent
gifts for husbands, wives, kids, significant others, and for handing out at company
events or as rewards for excellent service. It's a great way to help support RF
Aegis Power Systems is a leading supplier
of AC-DC and DC-DC power supplies
for custom and special applications. Aegis has been designing and building highly
reliable custom power supplies since 1995. They offer a complete line of switch
mode power supplies and power converters for a variety of markets including defense,
industrial, aircraft, VME, and telecom. Supports military, aircraft, EV, telecom,
and embedded computing applications. Design and manufacture of custom power supply
solutions to meet each customer's exacting specifications. Please visit Aegis Power
The dichotomy between the customer who is
worried about the service
shop owner ripping him off and the service shop owner who is worried about the
customer ripping him off is an old one. Given how even normally honest people allow
themselves a "white lie" here and there to consummate a business deal or pacify
the whims of an acquaintance, it is understandable how such suspicions come to be.
In this 1958 issue of Radio & TV News, Mac McGregor and trusty sidekick
Barney Jameson discuss how to handle customers who imply the desire for or outright
request (even demand) special consideration on repair services and/or replacement
parts. The steadfast policy of Mac's Service Shop was "cash-only" - no exceptions.
In the days before readily available credit cards and cash advances from ATMs, it
was usually up to the business to extend and take the risk for credit. Often collecting
on the promised funds consumed significant effort and on occasion resulted in failure...
Properly determining and applying error factors
in measurements is fairly straightforward if you understand the basic principles
of how errors propagate through calculations. Savitha Muthanna of the R&D department
of Keysight Technologies has a short article on the topic posted on the EDN website
Mathematical Approach to Estimate Probable Errors in a Measurement Task." Says
Savitha, "Very often, in the test and measurement industry, a measurement is made
by instrumentation, which is often subject to errors. It is difficult to estimate
the true value of the measured quantity given a number of indeterminate, uncorrelated,
and random factors. This article describes a method to estimate the probable error
of a measurement, specifically, the probable error of a direct measurement and an
indirect measurement. A direct measurement is one in which the quantity sought is
obtained directly by a measurement made by instruments indicating the sought quantity.
An indirect measurement..."
"Despite a lot of progress in recent years,
practical laser weapons that can shoot down planes or missiles are still a ways
off. But a new
liquid laser may be bringing that day closer. Much of the effort in recent years
has focused on high-power fiber lasers. These lasers usually specially doped coils
of optical fibers to amplify a laser beam, and were in originally developed for
industrial cutting and welding. Initially, fiber laser were dark horses in the Pentagon's
effort to develop electrically powered solid-state laser weapons that began two
decades ago. However, by 2013 the Navy was testing a 30-kilowatt fiber laser on
a ship. Since then, their ability to deliver high-energy beams of excellent optical
quality has earned fiber lasers the leading role in the current field trials of
laser weapons in the 50- to 100-kilowatt class. But now aerospace giant Boeing has
teamed with General Atomics..."
If you like reading about the historical
inventions of the RF and microwave field, then you will probably want not want to
miss Dr. Carter Armstrong's piece on the IEEE Spectrum website entitled
11 Greatest Vacuum Tubes You've Never Heard Of." The Carcinotron, the Gyrotron,
the Coaxitron, the Ring-Bar Traveling-Wave Tube, and the Ubitron are a few of the
devices you can read about - and see some detailed photos of them. "In an age propped
up by quintillions of solid-state devices, should you even care about vacuum tubes?
You definitely should!" Says, Mr. Armstrong, "If you'd told me I'd spend my
career working on vacuum tubes, I'd have said, 'No way. That's crazy!'" He has in
fact spent the last 40-some years working on vacuum devices...
Frost & Sullivan has presented Copper
Mountain Technologies with the 2020
Customer Value Leadership Award, in recognition of the company's strategic innovation,
technical excellence, and uniquely cost-effective and high−value offerings in the
global vector network analyzers industry. This award specifically highlights the
impact of the S5243 2−Port 43.5 GHz Compact VNA, which delivers quality measurement
and reliable results within a convenient and portable package. The economically-
priced analyzer meets design needs across a range of industries, enabling enhanced
product validation for a previously untapped collective of customers at small-to-medium
NorthEast RF's comprehensive
services include linear | circular polarized antenna measurements and OTA cellular
device pre-compliance. Up to 18" diameter and <10 kg weight. Antennas can be
rapidly evaluated and optimized using our fast near field spherical system. Test
results supplied in data file with pattern viewer software. A picture of the test
configuration is included to help aligned axis. Our selection of human head and
hand phantoms are ideal for verification of body worn devices. Turnaround time is
Radio-Electronics magazines' "Service
Digest" column regularly reported on issues relevant to the electronics servicemen
who repaired radios, television sets, phonographs, recorders, and similar items
- often in the customers' homes. Then, as now, professionalism and courteous behavior
was often rewarded with word-of-mouth referrals to friends and relatives, resulting
in new business opportunities. An interesting topic also included was the need to
observe extreme caution when working around TV tubes (CRT's) not just because of
the lethally high voltages present, but because of the
danger of tube implosion and the resulting scattering of glass shards. An example
given is that due to standard atmospheric press of 14.7 lbs/in2 on the outside of
the evacuated volume, a 17-inch screen CRT tube supports a total pressure of 3,322
pounds, or 1.66 tons...
The state of Virginia has for as long as
I remember had a law prohibiting the use of radar detectors in vehicles. For the
same amount of time, controversy has existed over whether the ban violates the Federal
Communications Commission (FCC) rules regarding
interception and divulgence of radio communications. As outlined in the statement
on the the FCC website (see below), there does not appear to be justification for
Virginia's law. To wit, "The FCC and the Communications Act do not forbid certain
types of interception and disclosure of radio communications, including: Mere interception
of radio communications, such as overhearing your neighbor's conversation over a
cordless telephone, or listening to emergency service reports on a radio scanner..."
"A research team led by University of Buffalo
has developed a new
3D-printed molecular ferroelectric metamaterial. The advancement has been published
in the Proceedings of the National Academy of Science and is a step toward making
these extraordinary lab-created materials more affordable and adaptable to countless
multifunctional technologies. It could benefit everything from acoustic blankets
for aircraft soundproofing to shock absorbers and elastic cloaks that shield sensitive
electronic systems from external mechanical disturbances. A metamaterial is any
material engineered to have a property that is not found in naturally occurring
materials. Ferroelectricity relates to crystalline substances that have spontaneous
electric polarization that's reversible by an electric field..."
Not everybody with a high temperature semiconductor
application in need of heat dissipation has access to a thermal management program
with a database of available commercial
heat sinks and/or an ability to analyze a custom-made heat sink. This article
from a 1965 issue of Electronics World magazine contains simple equations,
a handy chart, and instructions on how to use them to figure out what kind of heat
sink you need for your project. At the time TO−8 and TO−3 metal cans were a couple
of the most common sizes for which a large variety of heatsinks were available.
Withwave's Precision Test Adapters are designed
based on precision microwave interconnection technologies. This
1.85 mm (M) to 1.85 mm (M) right angle adapter is manufactured
to precise microwave specifications and constructed with male gender on both side.
The precision microwave connector interfaces ensure an excellent microwave performance
up to 67 GHz. VSWR: 1.30:1 (max) to 67 GHz. Connector body is passivated
stainless steel and the center contact is gold-plated brass...
Since 1996, ISOTEC has designed, developed
and manufactured an extensive line of RF/microwave
connectors, between-series adapters, RF components and filters for wireless
service providers including non-magnetic connectors for quantum computing and MRI
equipments etc. ISOTEC's product line includes low-PIM RF connectors components
such as power dividers and directional couplers. Off-the-shelf and customized products
up to 40 GHz and our low-PIM products can meet -160 dBc with 2 tones and
20 W test. Quick prototyping, advanced in-house testing and high-performance.
Designs that are cost effective practical and repeatable.
Here is a bit of "outside-the-box" thinking
from the vacuum tube era that is essentially a form of integrated circuit, where
the active and passive components are discrete rather than semiconductor. The concept
was to provide an assembly that could be plugged directly into a signal gain path
tube socket and provide an additional amount of amplification without needing to
do any special wiring or mounting of components to the chassis. The cost of $9.95
in 1951 is the equivalent of $99.99 in 2020 money, so it wasn't a cheap upgrade
- and that did not include the cost of an additional tube (about another $10 in
today's money). Given typical electronics service shop rates of just a couple bucks
per hour in the early 1950s, it might have been cheaper to pay the local guy to
do a customization of the circuit, and then tweak the operation of the entire television
or radio set. Having high voltage connections exposed outside the metal chassis
posed a serious electrocution potential (pun intended), and might have even made
the set more susceptible to interference...
"Electronics engineers continually look for
better insulating materials to use in their projects. Finding the right ones leads
to a longer product lifespan, along with improved performance and reduced heat during
use. Over the last several years, researchers have achieved particularly promising
results while using boron nitride to insulate electronics.
Boron nitride is a synthetic ceramic material available in solid and powder
forms. Since it has a similar microstructure to graphite, some people refer to it
as 'white graphite.' Unlike graphite, boron nitride performs well as an electronics
insulator with a higher oxidation temperature than that material. Scientists are
working hard to test and verify boron nitride's usefulness as an electronics insulator..."
Shakespeare Marine Electronics, a division
of- Jadex, Inc., is a U.S.-based manufacturer of both industrial and consumer products
for a wide variety of industries and applications. Shakespeare has an opening in
our Marine Electronics Division for a
Product Development Engineer. Position Summary The Product Development Engineer's
primary focus is to create and deliver technology solutions, which align with our
market needs, to drive growth within Shakespeare's Marine Antenna businesses. The
engineer will actively collaborate with the business teams and internal technical
team to deliver on project milestones and commercialize new offerings which meet
customers' needs. The development process is managed from the initial customer request
through final product transition to manufacturing. Project consideration is given
to product performance and cost enhancements which drive the businesses growth and
RF Cafe typically receives 8,000-15,000
website visits each weekday and about half that on weekends.
RF Cafe is a favorite of engineers, technicians, hobbyists, and students all
over the world. With more than 13,000 pages in the Google search index,
RF Cafe returns in favorable
positions on many types of key searches, both for text and images. New content
is added on a daily basis, which keeps the major search engines interested enough
to spider it multiple times each day. Items added on the homepage often can be found
in a Google search within a few hours of being posted. I also re-broadcast homepage
items on LinkedIn. If you need your company news to be seen, RF Cafe is the
place to be. Advertising begins at $40/month.
There are lots of audiophiles in the RF Cafe
audience who might appreciate this article on the characteristics of human hearing
and ways in which stereo hi-fi equipment attempts to reproduce realistic sound,
as if from a live performance. A handy-dandy chart is provided that shows the characteristics
of various audible frequency ranges, and the
kinds of speakers best suited for reproducing the sound. It was published in
a 1955 issue of Popular Electronics magazine when stereo hi-fi system building
was a major pastime, but still should be applicable today. If you do a search on
RF Cafe, you will find many articles covering stereo hi-fi equipment...
Berkeley Nucleonics Corporation (BNC) is
a leading manufacturer of precision electronic instrumentation for test, measurement,
and nuclear research. Founded in 1963, BNC initially developed custom pulse generators.
We became known for meeting the most stringent requirements for high precision and
stability, and for producing instruments of unsurpassed reliability and performance.
We continue to maintain a leadership position as a developer of custom pulse, signal,
light, and function generators. Our designs incorporate the latest innovations in
software and hardware engineering, surface mount production, and automated testing
Listen to the RF
Cafe Podcast! Hugo Gernsback, a name familiar to anyone who has been reading
some of the vintage electronics articles posted here on RF Cafe over the years,
was never short on ideas - both serious and fanciful. In 1947, when this editorial
appeared in his very popular Radio-Craft magazine, radio had become ubiquitous
in the commercial and consumer worlds, but he laments that the appliance had not
yet received its due compliment of
ancillary devices. Telephone, which had been around even longer that radio,
had a fair market of add-ons like a shoulder rest for the handset, an amplifier
for the hard-of-hearing, remote ringers, etc. There was not yet a selection of similar
devices for the convenience of radio listeners, and here Mr. Gernsback suggested
a few. Big money was to be made on such products. Among them he mentions a couple
humorous ideas like the "Warmeradio," where a chassis with inset...
Pronamic has introduced
high precision rain and precipitation gauges with unique technology. Resolutions
in the range of 0,1 (0.1) - 0,2 (0.2) - 0,25 (0.25) or 0,5 (0.5) mm gives ±2%
accuracy. Useful for various professional applications. Other notable features are
capability with LoRaWan and Sigfox (IoT) networks, weather, frost and heat resistance
and customizable cable connections. Pronamics precipitation gauges are designed
for high precision measurement of rain and snowfall. The base of our products is
the patented unique single spoon tipping bucket. One of the most accurate and reliable
automatic rain gauges on the market. All our professional rain gauges are manually
calibrated and offer very accurate measurement...
"The dangers of lithium-ion batteries, like
those used in smartphones and electric vehicles (EVs), catching fire or exploding
has been well-publicized. But the true impact of an EV battery catching fire and
the dangers that could result aren't known on a wide scale, which remains a question
mark as they become more widely adopted. To find out, researchers in Switzerland
EV batteries on fire in a series of experiments to test the potential for damage
and disaster in the case of EVs catching fire in parking structures or a tunnel.
What they discovered is that while in some cases, electric vehicle battery fires
are no more dangerous than other types of car fires, the smoke and soot they give
off contains toxic metal oxide..."
Listen to the RF
Cafe Podcast! "The Whistler and His Dog" is one of those tunes that you have
probably heard dozens of times but never knew the title of it (video at bottom of
page). It is mentioned in this installment of "Mac's
Radio Service Shop" from the November 1948 edition of Radio & Television
News magazine. Barney is said to have been whistling it while replacing an
output transformer on a receiver-recorder... a wire recorder that predated magnetic
tape types. The "20 Questions" theme is from the game where the player attempts
to guess the answer by asking a series of questions that narrows the possible results
until only the correct one is left - aka deductive reasoning...
Professional high frequency
TSA89 series of RF test cables with performance to 40 GHz. Precision connector
choices include; SMA, Type-N, 3.5mm, 2.92mm, & 2.4mm. Key features: High-frequency
point to point cable, light weight rugged double-shielded, flexible cable, low loss <0.68 dB/ft
@ 40 GHz, low VSWR < 1.35:1 (Typical < 1.25:1), RF leakage >−100 dB
to 18 GHz, temperature rated from -55ºC to 125ºC. 100% factory VSWR and insertion
loss tested. Wide selection of configurations & lengths. RoHS & Reach compliant.
Ideal for lab & production testing. Cables are in stock and available immediately
from Digi−Key. Made in the USA.
LadyBug Technologies was founded in 2004
by two microwave engineers with a passion for quality microwave test instrumentation.
Our employees offer many years experience in the design and manufacture of the worlds
best vector network analyzers, spectrum analyzers, power meters and associated components.
The management team has additional experience in optical power testing, military
radar and a variety of programming environments including LabVIEW, VEE and other
languages often used in programmatic systems. Extensive experience in a broad spectrum
of demanding measurement applications. You can be assured that our Power Sensors
are designed, built, tested and calibrated without compromise.
SF Circuits' specialty is in the complex,
advanced technology of PCB
fabrication and assembly, producing high quality multi-layered PCBs from elaborate
layouts. With them, you receive unparalleled technical expertise at competitive
prices as well as the most progressive solutions available. Their customers request
PCB production that is outside the capabilities of normal circuit board providers.
Please take a moment to visit San Francisco Circuits today. "Printed Circuit Fabrication &
Assembly with No Limit on Technology or Quantity."
November 1st's custom
Engineering Technology themed crossword puzzle contains only only words from
my custom-created lexicon related to engineering, science, mathematics, chemistry,
physics, astronomy, etc. (1,000s of them). You will never find among the words names
of politicians, mountain ranges, exotic foods or plants, movie stars, or anything
of the sort. You might, however, find someone or something in the otherwise excluded
list directly related to this puzzle's technology theme, such as Hedy Lamarr or
the Bikini Atoll, respectively. The technically inclined cruciverbalists amongst
us will appreciate the effort.