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4 of the February 2022 homepage archives. Monday the 7th
 This very extensive article on iron-core
inductors appeared in the November 1946 issue of Radio-Craft magazine.
The first part, published the month prior in October, was an introductions to terms
of
inductance and magnetism, while this one deals with actual design curves and
formulas. Iron core and air core inductors are the focus, and as you might guess
(due to the use of iron cores) the frequency range addressed is audio and relatively
low intermediate frequency (IF). In fact, separate treatment is given to coils operating
at DC (direct current) and AC (alternating current). Back in the day, not only were
most of the components inside a radio, television, record player, or other types
of electronics devices serviceable (i.e., replaceable), but the components themselves
were considered serviceable. That is, inductors, speaker coils, transformers, and
even some capacitors were often repaired or modified to fix non-working circuits
or to improve marginally functioning ones...
 Although this article was published in
Radio-Craft magazine at the very end of World War II, it describes
the efforts of the British Broadcasting Corporation (BBC) during the war years to
accommodate a large loss of trained electrical and communications engineers to active
military duty. The few qualified engineers remaining quickly went into action devising
a training regimen of electrical theory and hands-on training. Men (boys?) as young
as 16 years old, as well as women from 21 to 30 years old were selected after screening
for aptitude. More than 2,500 people became technical assistants and some top performers
earned certificates regarded in the industry as being on par with university degrees
in engineering. The effort once again lends credence to the old saying about necessity
being the mother of invention...
 Steve Taranovich has a good article on the
Electronic Design website entitled, "What
is the Essence of Quiescent Current?," a topic of importance to designers of
low power circuits and systems. With the plethora of battery powered devices ranging
from wristwatches to proximity sensors, long service life with minimal need to replacing
or recharging is essential and often is the prime factor for buyers deciding which
product to opt for given otherwise similarity of features. He begins: "For an electronic
circuit, a quiet state is one in which the circuit isn't driving any load and its
inputs aren't cycling. Most commonly used for the specification in a datasheet,
quiescent current is the current consumed by a circuit when it's in a quiescent
state. Quiescent current (IQ) also can be defined as the current consumed by an
IC in the no-load and non-switching but enabled state. Generally, quiescent current
is the input current consumed by the IC in any ultra-low-power consumption state.
Furthermore, IQ is the current needed to power a low-dropout (LDO) IC's internal
circuitry when the external load current is zero. Many designers may mistake quiescent
current as shutdown current..."
 Axiom Test Equipment, an electronic test
equipment rental and sales company has published a new blog entitled "Thermal
Chambers Boost Electronic Device Reliability," that informs people on the different
thermal chambers that can be used as part of a practical environmental test strategy.
This is vital when designing electronic devices for use over wide operating temperature
ranges. Depending upon their capabilities, thermal chambers can perform as many
as three types of temperature-based testing: thermal cycling, thermal shock, and
burn-in testing. When it comes to finding a suitable thermal test chamber for a
particular device under test, it's a matter of matching the capabilities of a thermal
test chamber to those test requirements. All in all, thermal chambers are typically
compared in terms of test volume, temperature range, the rates over which temperatures
can change, how tightly the temperature is controlled...
 Sure, there are lots of resources on the
Internet for identifying various
screw types, styles, shapes, and sizes, but sometimes there are so many that
it can be time consuming to peruse through them all, particularly if what you are
looking for is an older type. This chart from a 1960 edition of Popular Electronics
magazine might be just the thing you have been looking for when working on a piece
of vintage electronic and/or mechanical gear. Interestingly, at first I thought
there might be a typographical error in labeling one type screw head as "Bristo,"
thinking it is probably supposed to be "Bristol." I could not find many references
to a Bristo screw type in searches, but evidently it did exist back in the day.
They now go by the name Bristol...
 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 Cafe. Thanks...
 Copper Mountain Technologies develops innovative
and robust RF test and measurement solutions for engineers all over the world. Copper
Mountain's extensive line of unique form factor
Vector
Network Analyzers include an RF measurement module and a software application
which runs on any Windows PC, laptop or tablet, connecting to the measurement hardware
via USB interface. The result is a lower cost, faster, more effective test process
that fits into the modern workspace in lab, production, field and secure testing
environments.
Sunday the 6th
 This custom made
RF Amplifier theme crossword puzzle for February 6th is provided compliments
of RF Cafe. All RF Cafe crossword puzzles are custom made by me, Kirt
Blattenberger, and have only words and clues related to RF, microwave, and mm-wave
engineering, optics, mathematics, chemistry, physics, and other technical subjects.
As always, this crossword puzzle contains no names of politicians, mountain ranges,
exotic foods or plants, movie stars, or anything of the sort unless it/he/she is
related to this puzzle's technology theme (e.g., Reginald Denny or the Tunguska
event in Siberia). The technically inclined cruciverbalists amongst us will appreciate
the effort. Enjoy!
 With more than 1000
custom-built symbols, this has got to be the most comprehensive set of
Visio Symbols available for RF, analog, and digital system and schematic
drawings! Every object has been built to fit proportionally on the provided
A-, B- and C-size drawing page templates (or can use your own). Symbols are provided
for equipment racks and test equipment, system block diagrams, conceptual drawings,
and schematics. Unlike previous versions, these are NOT Stencils, but instead are
all contained on tabbed pages within a single Visio document. That puts everything
in front of you in its full glory. Just copy and paste what you need on your drawing.
The file format is XML so everything plays nicely with Visio 2013 and later...
 Triad 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 they can
help your project.
Friday the 4th
 Here is one of the first "call to arms" for
the
amateur radio community published in an American electronics magazine. It appeared
in the February 1942 issue of Radio News, which would have been the first
printing following the official declaration of war against Japan following the December
7th, 1941 bombing of Pearl Harbor naval base in Hawaii. A couple months of lead
time was required back then for submitting content and layout for a printing cycle,
so since the February issue was likely mailed in late January, anything that happened
in December probably wouldn't have made the cut. No mention is made of the soon
to follow prohibition against unauthorized transmitting by Hams for the duration
of the war, which went into effect December 8th (QST managed to get the
news into the January edition)...
 Innovative Power Products (IPP), with more
than 30 years of experience designing & manufacturing RF & microwave passive
components, is pleased to introduce their new Model
IPP-7164, 500-6000 MHz 90° hybrid coupler handles 100 watts CW
and comes in a SMD style package which is only 0.50 x 1.80 x 0.158 inches.
The IPP-7164 will combine two signals up to 100 Watts CW of total output power.
This part is ideal for many commercial, industrial or military broadband applications.
Electrical Specifications -- Frequency: 5000 – 6000 MHz, Power: 100 Watts
CW, VSWR: 1.70:1, Insertion Loss: <1.25 dB, Isolation: >13 dB, Phase
Balance: ±8°...
 For many years I have been scanning and posting
"Radio Service Data Sheets" like this one featuring the
Stewart-Warner 5-Tube Models 97-561 to 97-569 (Superheterodyne Chassis 97-56)
radio, in graphical format and with some or all of the text after running it through
OCR software. Electronics magazines back in the day would publish these for the
benefit of servicemen and do-it-yourselfers who did not have access to manufacturer
information documentation or could not afford to buy it from independent companies
like Sam's Photofact. 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. The thumbnail image of a beautifully restored example of a Stewart-Warner
Model 97-561 came from the RadioAttic.com website. I keep a running list of all
data sheets to facilitate a search...
 "Potential future transistors that consume
far less energy than current devices may rely on exotic materials called 'topological
insulators,' in which electricity flows across only surfaces and edges, with virtually
no dissipation of energy. In research that may help pave the way for such electronic
topological transistors, scientists at Harvard have now invented and simulated the
first acoustic
topological transistors, which operate with sound waves instead of electrons.
Topology is the branch of mathematics that explores the nature of shapes independent
of deformation. For instance, an object shaped like a doughnut can be deformed into
the shape of a mug, so that the doughnut's hole becomes the hole in the cup's handle.
However, the object couldn't lose the hole without changing into a fundamentally
different shape. Employing insights from topology, researchers developed the first
electronic topological insulators in 2007..."
 Little did Hugo Gernsback know when he wrote
this 1938 editorial in his Radio-Craft magazine about the
potential of television just how prescient he was - particularly in the realm
of eventually enabling remote commerce and banking. His vision involved having a
camera-phone type device that would allow real-time interaction between shoppers
and depositors, respectively, without either party needing to meet face-to-face.
76 years later we are not at that point (at least on a widespread basis); however,
the advent of online shopping and banking has fully permitted the kind of impersonal
transactions that Gernsback foresaw. Even with the growing popularity of Skype camera
phones, society still is far from the point where human-to-human transactions are
commonplace. Maybe at the century point (2038, a mere 16 years away) such a system
will be ubiquitous. There are probably some legal hurdles that will need to be resolved...
 It was a lot of work, but I finally finished
a version of the "RF & Electronics Schematic & Block Diagram Symbols" that
works well with Microsoft Office™ programs Word™, Excel™, and Power Point™.
This is an equivalent of the extensive set of amplifier, mixer, filter, switch,
connector, waveguide, digital, analog, antenna, and other commonly used symbols
for system block diagrams and schematics created for Visio™. Each of the 1,000 or
so symbols was exported individually from Visio in the EMF file format, then imported
into Word on a Drawing Canvas. The EMF format allows an image to be scaled up or
down without becoming pixelated, so all the shapes can be resized in a document
and still look good. The imported symbols can also be UnGrouped into their original
constituent parts for editing. Check them out!
 Please take a few moments to visit the
everythingRF website to see how they can assist
you with your project. everythingRF is a product discovery platform for RF and microwave
products and services. They currently have 267,269 products from more than 1397
companies across 314 categories in their database and enable engineers to search
for them using their customized parametric search tool. Amplifiers, test equipment,
power couplers and dividers, coaxial connectors, waveguide, antennas, filters, mixers,
power supplies, and everything else. Please visit everythingRF today to see how
they can help you.
Thursday the 3rd
 Introductory
tutorials on electronics are pretty much timeless in terms of fundamentals.
A few things have changes like the assumed direction of current flow from positive
to negative, to being what is now accepted as being negative to positive. A consequence
of that change is the "-hand" rules of electric and magnetic field generation and
induction have reversed from left to right and vise versa. Atomic models have changed
from the Bohr model of planetary behavior of discretely identified particles (electrons,
protons, neutrons) to the modern quantum mechanical model that uses wave functions
for defining the probability of a particle being at a certain location. None of
that really has a significant effect on learning Ohm's law and how passive components
like resistors, capacitors, and inductors influence voltages and currents in a circuit.
Accordingly, this 1942 "Practical Radio Course" appearing in Radio News magazine
is useful today for introducing readers to the basics of electronics...
 Exodus Advanced Communications is a multinational
RF communication equipment and engineering service company serving both commercial
and government entities and their affiliates worldwide. Power amplifiers ranging
from 10 kHz to 51 GHz with various output power levels and noise figure
ranges, we fully support custom designs and manufacturing requirements for both
small and large volume levels. decades of combined experience in the RF field for
numerous applications including military jamming, communications, radar, EMI/EMC
and various commercial projects with all designing and manufacturing of our HPA,
MPA, and LNA products in-house.
 Ironically, an RF Cafe visitor just within
the last couple days wrote about possibly getting his Amateur radio license in order
to permit live broadcasting of his kite-borne video camera system (known as "Kite
Aerial Video" [KAV]), or Kite Aerial Photography [KAP]). Slow scan television
SSTV has long been a popular facet of Ham radio since prior to broadband Internet
connections; it was the only practical method available. Older equipment was large,
heavy, power hungry, and relatively expensive, but today you can buy a much improved
camera for a few bucks that transmits real-time via an unlicensed 2.4 GHz wireless
link. That data stream can be recorded for later use of streamed real-time to the
Internet. As with so many other things, easy availability takes some of the challenge
out of it, but the world benefits from having all kinds of way-cool videos to watch...
 Reliance Test & Technology (RT&T),
a high-technology firm specializing in information systems, science and engineering,
and technical and administrative services, is seeking a
Radar Field Engineer for work at the National Radar Test Facility at White Sands
Missile Range. Note that this position only requires
an Associate Degree. The Radar Field Engineer (RFE) must be able to
collaborate as a contributing engineering team member providing technical expertise
and innovation to engineering staff in the development and sustainment of capabilities
and technologies. Specifically, the RFE plays an active role throughout the capability
development life-cycle by supporting the development, assembly, integration and
performance characterization of components, sub-systems and systems. Additionally,
the RFE acts as Technical Liaison between Development Engineering and Operations
Teams during the transition of capability insertion into operations by developing
documentation and providing both formal and informal training. The RFE follows capability
beyond initial operating capability and supports active Test Programs...
 One of the nice things about
antenna design articles is that regardless of when they were written, all that
is needed to make them entirely contemporary is to substitute a transistor schematic
symbol for a vacuum tube and substitute the units "kHz" and "MHz" for "kc" and "mc,"
respectively. If the article delves into detailed circuit design, a substitution
of "μF" for "mf" might also be required and depending on the frequency range, "pF"
for "mmf" or "μμF." Some readers might feel the urge to replace SAE units with metric
units, but even a hundred years ago there were people who needed to do that. "Aerial"
and "antenna" are still interchangeable in modern radio parlance...
 With more than 1000
custom-built stencils, this has got to be the most comprehensive set of
Visio Stencils available for RF, analog, and digital system and schematic
drawings! Every stencil symbol has been built to fit proportionally on the included
A-, B-, and C-size drawing page templates (or use your own page if preferred). Components
are provided for system block diagrams, conceptual drawings, schematics, test equipment,
racks (EIA 19", ETSI 21"), and more. Test equipment and racks are built at a 1:1
scale so that measurements can be made directly using Visio built-in dimensioning
objects. Page templates are provided with a preset scale (changeable) for a good
presentation that can incorporate all provided symbols...
 KR Electronics designs and manufactures
high quality filters for both the commercial and military markets. KR Electronics'
line of filters
includes lowpass, highpass, bandpass, bandstop and individually synthesized filters
for special applications - both commercial and military. State of the art computer
synthesis, analysis and test methods are used to meet the most challenging specifications.
All common connector types and package form factors are available. Please visit
their website today to see how they might be of assistance. Products are designed
and manufactured in the USA.
Wednesday the 2nd
 I wasn't able to verify Dr. Baker's
(VP of GE) prediction in 1957 of what the state of the television industry would
be by 1960. He said 10 million sets would be sold in 1960 vs. 7.5 million in 1957.
Some recent sources claim there were as many as
52 million TV sets total by 1960, so he might have been right. Transoceanic
scattering techniques were thought to be the method of choice for television broadcasts,
but we know that ultimately relay satellites would win out. It wasn't until 1962
that the Telstar bird carried the first TV signals, however. "Truly portable" transistorized
TVs would be appearing on store shelves within the next couple years. One in forty
Americans worked in the electronics manufacturing and service fields at the time.
I'm guessing the ratio is a lot lower today with only a small percentage of any
kind of manufacturing occurring domestically...
 "National Yang Ming Chiao Tung University
in Taiwan has reported
increased transconductance (gm) and reduced OFF-current (IOFF) for indium gallium
arsenide (InGaAs) fin field-effect transistors (FinFETs) from remote nitrogen plasma
passivation of the gate insulation layers [Hua-Lun Ko et al, IEEE Transactions on
Electron Devices, published online 20 December 2021]. The devices were fabricated
from n+-InGaAs on heavily p-type indium phosphide (p+-InP). The source/drain regions
were doped with silicon implantation and activation annealing. The fins were etched
with plasma, followed by citric acid sidewall smoothing and fin-width shrinking.
The fins were oriented in the (010) crystal direction to give the highest aspect
ratio. The gate insulators consisted of 0.8 nm aluminium nitride and 2.9 nm
hafnium dioxide, both applied using atomic layer deposition..."
 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. Three new
RF / microwave filter models have been introduced - an 11.875 GHz cavity bandpass
filter with a 100 MHz bandwidth, a 1750-1850 MHz / 2200-2500 MHz
cavity duplexer , and a 2.495-2.690 GHz cavity bandpass filter with a 195 MHz
bandwidth. Custom RF power directional coupler designs can be designed and produced
when a standard cannot be found, or the requirements are such that a custom approach
is necessary...
 Two items particularly caught my eye in this
group of news tidbits from a 1945 edition of Radio-Craft magazine. The
first was the drawing of a scheme for mobile-to-mobile as well as
fixed-station-to-mobile radiophone service - cellular telephones! A frequency
band of 152-162 MHz had been allocated for "urban mobile service." Towers and
base transceiver stations (BTS) would be erected along the most commonly traveled
routes to ensure contiguous coverage. Two years later, in 1947, Bell Systems initiated
its Mobile Telephone Service (MTS) based largely on the principle presented here.
The second thing that interested me was a plan by Raytheon to institute a microwave
relay system to facilitate intercontinental phone traffic. Bidirectional service
operated on 105 MHz and 107 MHz. Also in the news was rescinding of the prohibition
against production of non-war-related electronics for home use, government-funded
television research by the Ruskies, and FM radio stations...
RF Cascade Workbook is the next phase in the evolution of
RF Cafe's long-running series, RF Cascade Workbook. Chances are you have
never used a spreadsheet quite like this (click here for screen capture). It is a full-featured RF system
cascade parameter and frequency planner that includes filters and mixers for a mere
$45. Built in MS Excel, using RF Cascade Workbook 2018 is a cinch
and the format is entirely customizable. It is significantly easier and faster than
using a multi-thousand dollar simulator when a high level system analysis is all
that is needed. An intro video takes you through the main features...
 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.
Tuesday the 1st
 For those of us (most of us, actually) who
were born during or after World War II, mention of "the world war" can be ambiguous
since we have two to choose from. Chances are WWII is the one being addressed, but
it could also be WWI. When this "Aircraft
Radio Labs" article appeared in the February 1942 issue of Radio News
magazine, Americans had only been formally drawn into WWII two months earlier in
December 1941, so the stories and layout had already been formatted. Hence, when
author Lt. Col. Gardner wrote about "the World War," he was referring to WWI. The
Army's primary research and development facility was located at Wright Field in
Dayton, Ohio. Although the personnel there engaged in their own projects, they were
also responsible for generating specifications for private electronics companies
to bid on, and then to test those systems for conformance and performance once delivered...
 "A semiconducting material that performed
a
quantum "flip" from a conductor to an insulator above room temperature has been
developed at the University of Michigan. It potentially brings the world closer
to a new generation of quantum devices and ultra-efficient electronics. Observed
in two-dimensional layers of tantalum sulfide only a single atom thick, the exotic
electronic structure that supported this quantum flip was previously only stable
at ultra-cold temperatures of -100 degrees Fahrenheit. The new material remains
stable at up to 170 degrees Fahrenheit. 'We've opened up a new playground for the
future of electronic and quantum materials,' said Robert Hovden..."
 Exodus Advanced Communications, a multinational
RF communication equipment and engineering service company serving both commercial
and government entities and their affiliates worldwide, announces their
AMP2103P-LC, dual-mode (CW & pulse) solid state power amplifier (SSPA) is
ideal for automotive pulse radar, electronic warfare, EMC testing and commercial
applications. Pulse widths to 560 μsec, duty cycle to 10% with PRF up to 10 kHz,
60 dB gain and outstanding pulse fidelity makes the AMP2103P-LC perfect for
a wide variety of systems. Monitoring parameters for forward and reflected power
in watts and dBm, VSWR, voltage, current, and temperature, with unprecedented reliability
and ruggedness. Package format is a compact 7U chassis measuring 12.25"H x 19"W
x 29"D, weighs 90 lbs. (nominal)...
 In another blast from the past, I just found
an advertisement by Bell Telephone Laboratories announcing
"Twistor" memory in a 1958 edition of Radio-Electronics magazine. According
to Bell, their radically new "Twistor" magnetic memory matrix was vastly superior
to conventional ferrite core memories. It used hair-thin magnetic wires (more like
a flattened tape) interwoven with equally thin copper wires to store and read out
ones and zeroes. Doing so reduced manufacturing costs, by eliminating the relatively
expensive ferrite cores and eliminating the difficult job of threading the read,
write, and sense wires through the core centers. Twistor memory also required less
current to operate, was denser, and weighed less than core memory. Within a decade
CMOS RAM was available to replace the magnetic memory, but from a reliability standpoint,
the Apollo space program selected magnetic core memory for the manned flights...
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 Cafe. Thanks...
 Innovative Power Products (IPP) has over
30 years of experience designing & manufacturing RF & microwave passive
components. Their high power, broadband
couplers, combiners, resistors, baluns, terminations
and attenuators are fabricated using the latest materials and design tools available,
resulting in unrivaled product performance. Applications in military, medical, industrial
and commercial markets are serviced around the world. Please take a couple minutes
to visit their website and see how IPP can help you today.
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. I also
have an extensive list of
Recently Added topics.
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