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 New:
Rectangular Waveguide Calculator. RF Cafe's spreadsheet-based
engineering and science calculator,
Espresso Engineering Workbook™, is a collection of electrical engineering and
physics calculators for commonly needed design and problem solving work. The filter
calculators do not provide just amplitude, but also phase and group delay (hard to get outside
of a big $$$ simulator). It is an excellent tool for engineers, technicians, hobbyists,
and students. Equally excellent is that Espresso Engineering Workbook™ is provided
at no cost, compliments of my generous sponsors. 51 worksheets to date...
 DAS DEALS
Marketplace, RF Cafe's newest supporter, is a B2B-only marketplace, meaning
we exclusively work with established businesses in the telecom, wireless, and
networking industry to buy and sell related products such as cables, antennas,
DAS systems, RF passives, accessories, and test equipment. All submissions are reviewed
and approved before any products are listed. Most products on DAS DEALS can be purchased
directly using a credit card at checkout. Can't find it on DAS DEALS? We probably
know who has it. If you're looking for a product that's not listed on our site,
visit the In-Demand Request page and submit a request.
 I did a little research on this article
about John H. Nelson's work on how the positions of planets affect
magnetic storms on Earth. It looked a little more like astrology
than science, but as it turns out, Nelson's findings gained support in both
the astronomical and meteorological fields. Naturally, the astrology crowd claimed
him as part of their goofiness, but that wasn't Nelson's fault. He published
a book in 1974 titled ,"Cosmic Connections." Yeah, even that sound like an astrology
title - poor choice (or maybe he was trying to fool the contemporary Pharisees in
to buying his book). The book is out of print now, and I could not find any contemporary
work that leverages Nelson's work...
 If you want to know what was really going
on at some point in the past, there is usually nothing more reliable than reading
a print story or advertisement from the era. That way you're getting the news
"straight from the horse's mouth," so to speak, rather than being interpreted
or filtered by some unassociated source. This report on "The Transistor in Industry" was written in 1956 by Mr. Frank
Durat, a product manager at Raytheon, at a time when transistors were first making
inroads for replacing the venerable vacuum tube (valve) which had launched and propelled
the electronics industry since 1908 when Lee de Forest introduced the triode Audion
amplifier. Germanium and silicon were the semiconductor base crystals du jour, and
achieving the requisite purity was a primary concern for advancing the state of
the art for higher frequencies, power handling, and circuit density (for integrated
circuits)...
 My
50-year high school reunion is here. Tempus fugit. These images were scanned
from my 1976 yearbook for
Southern Senior High School in Harwood, Maryland. Only pages
with information on Seniors is included. A full list of all the names that go with these photos can be
found at the bottom of the page. Having them in text format (versus a photo)
will allow search engines to find your name and associate it with Southern
Senior High School. Oh, and yes, all the photos are in B&W; there are only eight
pages with color in the entire book! I used AI to colorize a couple of them - a
technology not even deemed possible in 1976.
 Anytime I see a photo or story about the
1964 New York World's Fair, I immediately think of the scene
at the end of the first "Men in Black" movie when Agents K and J face off with the
alien invader who has come to Earth in search of "The Galaxy." This story from an
April 1964 issue of Electronics magazine reports on preparations made for
the grand opening on April 22 of that year. Based on the typical three to six month
lead time for publishing magazines back in the day, this material would have been
gathered long ahead of time. Of course now that half a century has passed we hardly
consider any of the whiz-band technology presented there as being anything wonderful,
but then half a century from now our grandkids will laugh at what we consider amazing
at the present time. Here is an interesting statement..."
 Welcome to the RF
Frequency Mixers
Quiz, a technical assessment focused on the critical non-linear components that
enable frequency translation in transceivers and test equipment. Whether you are
designing heterodyne receivers, analyzing local oscillator (LO) leakage, or striving
to minimize spurious intermodulation products in your signal chain, a deep understanding
of mixer dynamics is indispensable for high-performance RF design. This quiz covers
the core principles of frequency conversion, exploring topics such as conversion
loss, isolation, port-to-port feedthrough, and the generation of mixing products.
By testing your grasp of these essential concepts, you refine your ability to optimize...
 Albert Einstein declared and proved that
time is relative and depends on the observer's perspective. To someone sixty
years old, the year 1971 seems like it was just yesterday, but to people born a
couple decades ago, it seems like ancient history. Even so, I am taken by surprise
when I read a story from a 1971 issue of Popular Electronics that has produced
a list of "early computers" and it includes models like the ENIAC and Harvard
Mark I. Instinctively, the IBM XT, Apple II, and Packard Bell, and Compaq
lines of personal computers (PCs) come to mind. In 1971, there were no PCs. However,
if you compile a list of antique computers, then the aforementioned names apply.
This article does provide a nice recounting of the evolution of digital computers
from Charles Babbage's mechanical Difference Engine through those vacuum tube-based
electronic computers...
 These two advertisements appeared in the
July 1935 edition of QST. Bliley Electric is still in business here in
Erie, Pennsylvania as
Bliley Technologies. They make crystals and frequency sources.
Gross Radio has been out of business for quite a while. I included it mainly to
illustrated how large radio transmitters used to be - these things were installed
in people's attics and basements back in the day. This particular model, the
CB-100, is a "100-Watt Radiophone & C.W. Transmitter completely housed in an
entirely enclosed floor rack of ingenious design." It operated in the 1.7, 3.5,
7 and 14 MHz bands. For comparison, iCOM makes a 1 kW power amplifier today
covering those bands...
 Dr. Lee DeForest might have had something
like National Public Radio (est. 1970) in mind when he penned this article in 1933.
In it, the famous vacuum tube amplifier inventor lamented and criticized the commercialization
of broadcasts because of all the paid product announcements (aka commercials) that
had been steadily increasing over the years. He also was critical of the "hit-or-miss,
higgeldy-piggeldy mélange program basis" of programing; i.e., the same station playing
a mix of jazz, opera, swing, syndicated story-telling, etc. The good doctor did
not elaborate on where funding for such dedicated, uncorrupted broadcasts would
originate if not from paying advertisers, and I do not recall ever reading about
a DeForest Radio Network paid for by his vast fortune. I don't like commercials
any more than the next person, but a company deserves time to pitch its products
and/or services if it helps deliver a source of entertainment to you that...
 Each week, for the sake of all avid cruciverbalists
amongst us, I create a new
technology-themed crossword puzzle using only words from my custom-created
lexicon related to engineering, science, mathematics, chemistry, physics, astronomy,
etc. 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,
see someone or something in the exclusion list who or that is directly related to
this puzzle's theme, such as Hedy Lamarr or the Bikini Atoll, respectively...
 John T. Frye's monthly "Mac's Radio Service Shop" techno-drama, written in story form
- was usually an incognito lesson on circuit functionality or troubleshooting, how
to deal with customers, industry regulations and news, or an introduction to new
components and equipment. As the "Unusual New Equipment" title suggests, this time
Mac described a few new items added to the service shop to aid in their work. Often
when reading one of the episodes, I do a Google search on specific components or
equipment mentioned in the article. He describes a special-purpose CRT (Sylvania's
new 5AXP4 Television Receiver Check Tube) that could be used universally for troubleshooting
in place of a wide variety of installed picture tubes. I found one for sale on eBay
for $39.95. There is not much you cannot find on eBay if you watch long enough...
 This is a different type of
electronics-related quiz from Quizmaster Robert P. Balin.
Mr. Balin created many monthly quizzes for Popular Electronics magazine.
Here you are provided a series of images and a list of men's first names, and you
need to match the image to the name. There are nine in all. Sure, it's kind of hokey
(especially B and I), but it is a good end-of-the-work-day challenge challenge to
help pass the time until the weekend begins...
 While not a second-hand store junkie, I
do like to occasionally make the rounds of the local Salvation Army, Goodwill, and
other independent shops to see what kind of relics are donated. Since eBay, Etsy,
and their kind have gained immensely in popularity, it is getting harder to find
anything useful other than clothes and kitchen wares. A few months ago Goodwill
had a 1910s vintage
cabinet -style Edison disc phonograph (as opposed to wax cylinder)
that was in very good condition, complete with a handful of styli and a couple old
records. The original finish over smooth mahogany and burl veneers had only a few
scratches and could easily be polished to look practically new. The metal hardware
could have stood a fresh coat of black paint due to nearly a century of oxidation.
Even the original nomenclature plate looked factory-new, and a clearly legible paper
plaque...
 Bell Labs, having been responsible for creating
the first positive amplification point contact transistor just before Christmas
1947, continued to lead the way in semiconductor research and new product announcements
for many decades. This little tidbit was tucked away at the bottom of page 120 in
the May 1954 issue of Radio & Television News magazine. It reported on "the
purest substances in the world" being created there in the form of 99.99999999%
(aka 10N)
pure germanium crystals, which are used as seed for growing boules
for device production. That's one rogue impurity atom in ten billion germanium
atoms. Modern monocrystalline silicon boules are typically 7N or better...
 This
Attenuator Calculator
is probably unlike any you have seen. Not only does it calculate resistor values
for both balanced and unbalanced Pi and Tee topologies, but it also calculates the
power dissipated by each resistor, and calculates the input and output VSWR when
1% tolerance resistors are used rather than ideal values. Another page provides
all equations and schematics for all four configurations.
 Like so many things in life that
we take for granted - aspirin, automatic clothes washers, drill
motors and bits, eyeglasses, rifles, bicycles, transistors, to name a few - we rarely
think about the effort that went behind the end product that is now enjoyed. Even
relatively simple devices like scissors are the result of someone saying to himself
or herself, "Self, I need something to make cutting fabric and paper and hair simpler
and neater, so what might that thing look like?" Then, after making a working prototype,
improvements are made based on empirical testing from usage, improvements are made
in the form factor, materials, size, etc., until evolution results in what can be
purchased today. If you have ever been in a product design cycle, either privately
or corporately, then you know the process well...
 Found in what is the first issue of
Electronics Illustrated magazine that I have bought are these Amateur radio
related comics entitled, "Over and Out." The cartoonist's signature is simply "Rodrigues,"
which according to a Google search might be Charles Rodrigues (who also contributed
to other tech magazines as well as to National Lampoon). I have to admit
to needing to look up the "Yanqui aggressors" thing on the one comic, and then it
made sense: Yanqui= Yankee. The last comic with the parrot is pretty funny; it's
sort of the Ham radio equivalent to an auto-repeat telephone dialer like what you
would use to call into a radio show during a listener contest...
 During World War II, the government
created a specification for military-grade cable and assigned the designation RG-#/U, where "RG" stands for Radio Guide and the "U" stands
for Utility. The "dash number" was sequentially issued and has no bearing on the
characteristics of the cable. Founded in 1902 in St. Louis, Missouri, by Joseph
Belden, the eponymously named company has been and continues today designing and
manufacturing coaxial cable. Most of the RG-x/U coaxial cable types displayed in
this 1951 Radio & Television News magazine advertisement are still
being used today, in particular the very familiar RG-58/U (50 Ω), RG-59/U (75 Ω),
RG-8/U (50 Ω), and RG-11/U (75 Ω)...
 Welcome to the RFCafe
Isolators &
Circulators Quiz, a technical overview focused on non-reciprocal microwave components.
These specialized devices are the primary tools used to protect sensitive signal
sources from reflected power and to route signal flow in multi-stage RF systems.
Whether you are isolating a high-power transmitter from a high-VSWR antenna, developing
duplexers, or optimizing the signal isolation between cascaded amplifiers in a precision
measurement setup, a solid grasp of circulator and isolator physics is essential.
This assessment addresses the fundamental properties of ferrite-based non-reciprocal
hardware, including insertion loss, port-to-port isolation, power...
 How far do you commute each day for the
privilege of doing your part to push back the frontiers of technical ignorance and
to boldly go where no engineer - or technician - has gone before. Do you know what
the cost equates for you each year? This handy-dandy infographic lays out some
gruesome
numbers. Those with a weak stomach probably should pass on viewing this one.
Here's a hint at what you will see: See that big $795 in the thumbnail image?
That's the average cost per year for commuting -- per mile! Yessiree, if you
live just 10 miles from work, you're losing nearly $8,000 per year, depending
on you automobile type, on gas, tires, maintenance, devaluation, and loss of your
personal time (which is valuable, after all). Back in the early 1990s I drove about
45 miles each way...
 Joe Cahak, owner of Sunshine Design Engineering
Services in Ramona, California, has written a white paper entitled, "Measuring Semiconductor Device Input Parameters with Vector Analysis."
This article covers a recent test experience that utilized some thinking about the
test fixture, the bias requirements and the device mounting and special calibration
offsets needed to de-embed the test fixture response from the device response within
the test fixture. The device also had to have bias on several ports simultaneously.
We had to establish a "reference plane" within the fixture, from which we can use
the Vector Network Analyzer's Port Extension or Phase Offset to dial out the
distance from our 1 port calibration reference plane to the point of short reference
within the fixture. With this phase offset compensation we can then measure...
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Loading history...
The RF Cafe Homepage
Archive is a comprehensive collection of every item appearing daily on this
website since 2008 - and many from earlier years. Many thousands of pages of unique
content have been added since then.
 When is the last time you heard someone refer
to electronics as "solid state?" It was a necessary differentiator during the era
of transition from vacuum tubes to semiconductors. Mere utterance caused fear in
some, and futuristic hope in others. "Solid State" was a big buzz phrase in marketing
to household consumers and industry planners. Why, I ask, was "solid state" chosen
as the term to counter vacuum tube electronics? Did we ever refer to tubes as "gaseous
state" or "plasma state" devices? Maybe the "solid" part of "solid state" evoked
a sympathetic emotion with the coincident hippie / beatnik era population's usage...
 While doing a little research about a
Popular Electronics article, I ran across some examples of
electronic
component art / sculpture. A Google image search on the topic yields hundreds
of results, with most being duplicates. I always try to locate the original image
so as to give proper credit to the designer, but more often that not the pictures
are posted on websites without a reference. To avoid unfairly attracting attention
from the creator's work, I always use thumbnails and provide hyperlinks to the websites
where I found...
 Filtering, timing, coupling, and energy storage
are the most common uses for
capacitors (not to mention their use in electronic component sculptures).
Metallized paper or plastic, plastic film, mica, ceramic, electrolytic, and a few
other capacitor types have been around for a long time, with newer formulations
of electrolytics providing higher charge storage density, lower leakage, greater
stability, lower cost, wider operational temperature ranges, more robust construction,
etc. We now have supercapacitors that...
 Thanks
to RF Cafe visitor Alois B. for providing additional resources for the material
dielectric constants page. Now included are
Electrical
Properties of Insulators and
Dielectric Properties of Materials...
 RF, IF and baseband amplifiers; RF, IF, and
baseband filters; fixed and tunable local oscillators, single- and double-balanced
mixers, attenuators, envelope detectors and phase detectors, directional couplers,
power combiners and dividers, et cetera, are all component types used for
receiver systems regardless of whether vacuum tubes or transistors
comprise the active parts. In 1972 when this article appeared in Popular Electronics
magazine, people were beginning to get comfortable with the idea of transistorized
products replacing the familiar tube. Instant-on televisions and radios were...
 This rare
HP 5212A Electronic Counter was found in a second-hand shop
sitting in with a bunch of random electronic gear. The "HP" on the front panel piqued
my attention, so I carried it to the sales desk and asked the nice lady to plug
it in, figuring if the front panel lit up and none of the smoke that makes electronics
work leaked out, I'd buy it. It did, it didn't, and I did, respectively. The outside
condition is pretty good, with most of the scratches being on the top and bottom.
Some oxidation is present on the bare aluminum chassis components, but a little...
 The July 1966 issue of Popular Electronics
began a series of
anecdotal instances of stupid and/or funny remarks made by people
about electronics. Some are supposedly by those who are in the trade and should
know better. I have to take issue with and question the veracity of one instance
in this first sequel, which claims a technician coming out of military service are
apt to make statements such as fuses being bad because they are "shorted." It must
have been submitted by an anti-military hippie of the era, because there's no way
anything other than a vanishingly small minority of techs who have spent two to
four years or more years servicing real electronic equipment would say ...
 Each week, for the sake of all avid cruciverbalists
amongst us, I create a new
technology-themed crossword puzzle using only words from my custom-created
lexicon related to engineering, science, mathematics, chemistry, physics, astronomy,
etc. 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,
see someone or something in the exclusion list who or that is directly related to
this puzzle's theme, such as Hedy Lamar or the Bikini Atoll...
 When you think about wireless (radio) saving
the day for reporting trouble at sea, most of us (including, until now, me) think
of the RMS Titanic incident that occurred on 14 April, 1912. Her telegraph operator,
Jack Phillips, managed to get off an SOS (actually "CQD" in the day) message that
was picked up by the ship Carpathia. In fact, this story of the SS Republic recounts
events on January 23, 1909 when the good ship collided with Italy's Florida. Radio
operator Jack Binns managed to get off a CQD message using backup batteries once
he discovered the ship's power had gone down. Jack Phillips had the...
 Is it permissible to say, "Pig Latin," these days without being jailed for engaging
in hate speech or being accused of cultural insensitivity? ...not that I really
care. Carl Kohler's story from the November 1966 issue of Popular Electronics
had me waxing nostalgic over a similar scenario from my own boyhood. It begins with
Mrs. Kohler (aka "Goodwife") suggesting that she and Mr. Kohler resort
to speaking in Pig Latin in order to prevent their mischievous sons from learning
where the Christmas presents were being hidden. My parents did exactly the same
thing to my sisters and me - and that...
 Here are a couple more
electronics-themed comics from a 1969 edition of Electronics
World magazine. I like the radio astronomy comic. Enjoy...
 You probably won't find too many people
stacking television antennas these days, but many Hams still do
it. Vertical stacking is used primarily to increase overall gain without appreciably
altering the azimuth beam, while horizontal stacking forms a tighter azimuth beam
without appreciably affecting the overall gain. When it comes to optimizing antenna
designs installations for operations below about a gigahertz, Amateur Radio practitioners
have pretty much written the book on the subject - actually, they have written hundreds
of books on the subject. Antenna stacking is often used...
 Before there were electric generators onboard
airplanes to power communications equipment, aviators relied on storage batteries
to operate their radios. Before that, there were no radios at all aboard airplanes.
Although Wilbur and Orville Wright first piloted their Wright Flyer in 1903, by
the end of the decade airplanes were becoming a common sight across the country
and across the civilized world. By the middle of the second decade experiments were
being done with airborne radio. They were heavy vacuum tube units with heavy
lead-acid batteries. Antennas sometimes hundreds of feet long needed to be
reeled out and in once at altitude. The earliest transmitter (for 2-way
communications) were spark gap types, meaning of course Morse code was the
medium...
 Each week, for the sake of all avid cruciverbalists
amongst us, I create a new
technology-themed crossword puzzle using only words from my custom-created
lexicon related to engineering, science, mathematics, chemistry, physics, astronomy,
etc. 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,
see someone or something in the exclusion list who or that is directly related to
this puzzle's theme, such as Hedy Lamar or the Bikini Atoll, respectively...
 Here's a gimmick that never really caught
on. In the 1960's, Antenna Specialists promoted their Model M-148 Co-Ax Omni Antenna
"with visual RF indicator." That indicator was a neon light bulb
at the tip which lit up when the transmitter was keyed on. Not only would this novel
feature let you know when your transmitter was broadcasting, but it would also "guide
mobiles visually to your 10-20." OK, maybe at night, but it certainly wouldn't have
been bright enough during the day to even see. Alas, the public evidently didn't
impress the buying public as much as it did the designers. Maybe it had something
to do with... |
You probably won't find too many people
stacking television antennas these days, but many Hams still do
it. Vertical stacking is used primarily to increase overall gain without appreciably
altering the azimuth beam, while horizontal stacking forms a tighter azimuth beam
without appreciably affecting the overall gain. When it comes to optimizing antenna
designs installations for operations below about a gigahertz, Amateur Radio practitioners
have pretty much written the book on the subject - actually, they have written hundreds
of books on the subject. Antenna stacking is often used...
