|
 In the early 1950s, the U.S. Navy built
what was at the time the world's largest and most powerful radio broadcast transmitter
station at the
Jim Creek Naval Station on Wheeler Mountain in Washington state.
Its 1.2 MW, 24.8-to-35 kHz VLF transmitter (call sign NLK) can reach anywhere
in the world, even to submarines. A half wavelength at 24.8 kHz is 19,830 feet.
Photos indicate that the transmitter is located in the middle of a dipole arrangement.
"Catenary cables," if you are unfamiliar with the term, refers to the sagging shape
assumed by both the antenna cables and the tower support cables. "Catenary" stems
from the word "chain" since it is in the form...
 Carbon tetrachloride (CCl4) was
a common cleaning agent used commercially through about the early 1950s when it
began receiving a lot of bad press due to a linkage to severe kidney damage from
exposure even in vapor form. I notice that Mac mentions having read an article about
the potential danger of "carbon-tet" in an edition of Radio & Television
News magazine, not coincidentally the publication where the "Mac's Radio Service Shop" series appears. He also mentions a publication
called International Projectionist, which included instructions for cleaning
movie film with carbon tetrachloride, and had...
 It is amazing to me how many times I read
an article, whether in a vintage magazine like this 1947 issue of Radio News,
or a current edition of QST, how when discussing maximum power transfer
from a source to a load, the author states merely that the load impedance must equal
the source impedance. The fact of the matter is that the source and load impedances
must be the
complex conjugates of each other in order for maximum power transfer
to occur. That is to say that if the source has a complex impedance of R + jX, then
the load must have a complex impedance of R - jX (and vice versa)...
 Unlike today when resources of all types
seem to be endlessly available, during World War II countries needed to collect
and recycle much in the way of metal, rubber, cloth, and other basic materials for
re-purposing into products used in fighting the enemy. Media coverage of bottle,
metal, and tire drives showed children pulling Radio Flyer wagons loaded to overflowing
with such items gathered from trash piles and soliciting neighborhood residents
for anything that could be spared. Raw materials were not the only type of items
needed, however. "Use
it up, Wear it out, Make it do, or Do without" was the slogan. Finished goods
like electronic components - vacuum tubes, transmissions cable, transmitters and
receivers, tuning capacitors, d'Arsonval meter movements, and other parts -
were sorely needed by manufacturers both for building new equipment and for servicing
damaged gear. After the war was won, the War Assets Administration...
 Around the time when this "The
Great QSL Quarrel" appeared in a 1960 issue of Electronics Illustrated
magazine, there was a long-standing friction between amateur radio operators and
shortwave listeners regarding the exchange of QSL confirmation cards. Far from mere
paper, many hams view their custom-designed cards as valuable reflections of their
personal rigs and efforts. Consequently, they often discard subpar listener cards
that are illegible, aesthetically dull, or lacking meaningful data. To ensure their
reports are actually welcomed, shortwave listeners are urged to adopt higher standards:
utilizing professional printing or clear handwriting...
 A momentous development that changed the
field of radio communications warranted merely a half-page announcement in 1935
when
frequency modulation inventor Edwin Armstrong had his article
published in Radio-Craft magazine. It indisputably changed the world while causing
poor Mr. Armstrong much grief while defending his right to the invention. Spread
spectrum modulation / demodulation would be the next big communications advance
that began with the frequency hopping (FHSS) scheme dreamed up by Hollywood actress
Hedy Lamarr and pianist Antheil George during World War II. Direct sequence
spread spectrum (DSSS) followed in the digital age, and since then I do not know
of any fundamentally new communications technology in that time...
 Since 2005, San Francisco Circuits has been
a trusted U.S. provider of advanced PCB manufacturing and assembly solutions for
R&D innovators, prime contractors, and integration experts.
Flying Probe Testing (FPT) has long been a reliable method for validating PCB
designs, particularly for prototypes and low volume production. Unlike traditional
in circuit testing (ICT), which relies on custom built fixtures, flying probe systems
use movable probes to test electrical connections directly, eliminating the need
for dedicated hardware. Flying probe testing uses multiple programmable probes to
contact pads...
 The February 1947 issue of Radio News
only had two
electronics-themed comics. Many months have up to half a dozen
comics. Maybe the winter blues had set in with the magazine's illustrators. The
first comic is a tad bit prescient in that it depicts a robber running past a television
store and seeing a TV in the front display window showing a real-time video of the
cop chasing him. That was way before there was a video surveillance camera on every
street corner. I haven't discovered a vintage magazine yet with someone taking a
"selfie." There is a growing list...
 These are the schematics and parts list
for vintage
Emerson vacuum tube radio models 501, 502, and 504;
Crosley model 56TD-W; and
Arvin model 140P as they appeared in the November 1947 issue of
Radio News magazine. I scan and post these for the benefit of hobbyists
and historians seeking such information. As time goes by, there is less and less
likelihood that records of these relics from yesteryear's archives will be made
available. As with all historical information, it takes someone with a personal
interest in preserving the memories in order to fulfill the mission...
 John Comstock created many crossword puzzles
for Radio & TV News magazine, and a couple others, in the 1950s and
1960s. This one titled "Test
Equipment Teaser," appeared in the March 1959 issue. It is not a densely populated
grid with complex intersections of crossing words (unlike the RF Cafe crossword
puzzles, which do have them), but at least with this kind, all of the words and
clues are directly related to electronics and technology (like RF Cafe crosswords).
Anyway, it shouldn't take you too long to zip through this one. The only clue/word
that might give you trouble is 32 Across. Enjoy...
 Exodus Advanced Communications' representatives,
in discussions during last month's EMV (Elektromagnetische Verträglichkeit) show
in Cologne, had many attendees express interest in receiving an Exodus brochure
covering our RF amplifier solutions for
drone (UAS) applications. Exodus supports defense contractors with a family
of RF amplifier modules optimized for UAV, drone, mobile, and fixed Counter-UAS
platforms. At the center of this portfolio is the
AMP10008, an ultra-lightweight solid-state RF amplifier module
that demonstrates what is possible when SWaP is treated as a primary design driver
rather than a compromise...
 The cover of this month's Radio &
Television News magazine is part of the issue's story on performance testing
of resistors. The author was an engineer for
International Resistance Company (IRC), which is still in business
as part of TT Electronics. The massive ovens were used for load-life testing to
certify resistor products for both military and commercial uses. When required,
humidity enclosures subjected resistors to increased levels to test for insulation
breakdown at high voltage. As the article observes, since a 10-cent resistor can
take down a multi-thousand system, it is important to guarantee every component's
integrity...
 Werbel Microwave is a manufacturer of RF
directional and bidirectional couplers (6 dB to 50 dB) and RF power dividers
/ combiners (2- to 16-way) with select models operating up to 26.5 GHz and
100 W of CW power (3 kW peak). All are RoHS and REACH compliant and are
designed and manufactured in our Whippany, NJ, location. Custom products and private
label service available. Please take a couple minutes to visit their website and
see how Werbel Microwave can help you today.
 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 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. 49 worksheets to date...
 Although the Japanese attack on Pearl Harbor
on December 7, 1941, was a complete surprise and shock to the nation, that fact
that the United States would eventually be drawn officially into World War II
was well known. The amateur radio community had begun talking about the potential
impact on radio communications hobbyists earlier in the year, as evidenced by articles
printed in QST and other magazines. Within a couple weeks of Congress declaring
war, all unauthorized transmissions from Ham stations were terminated in order to
prevent both intentionally and unintentionally conveyance of information that could
proves useful by the enemy. Along with being a patriotic bunch that were eager to
help defeat Axis powers, they also...
 Here, for your work-week enjoyment, are
a half dozen
electronics-themed comics that appeared in the January 1950 edition of Radio &
Television News magazine. When is the last time you saw a comic in a technical
magazine? I particularly like the one with the "green worm" displaying on the television.
There is a list of other comics at the bottom of the page...
 If this Radio-Craft magazine article
is accurate, it was sometime around 1935 that the
8-pin glass-encased vacuum tube base came into existence. The
glass-metal designation refers to these being glass enclosed equivalents to otherwise
metal encased vacuum tubes. Evidently, the relatively new (and expensive) line of
metal tubes sported 8-pin bases so these glass tube designs had to conform in order
to be suitable substitutes...
 If some of the images in this issue of
Electronics Illustrated magazine were made within the last couple years,
I would swear they were AI-generated. Surely, there are not really
people as stupid as those shown here... but, alas, there apparently are. These
photos were published in 1960. The ARRL has always published recommended safety
practices - particularly regarding high voltages from overhead power lines and lightning
strikes. How anyone, like the guy in the first photo, could ever even considering
standing on a ladder and sticking his arm between even the 240-volt house supply
line from the utility pole - without even a current-limiting device like a fuse
or circuit breaker inline - is beyond comprehension. Clearly, the antenna already
installed...
 This episode of "Mac's Radio Service Shop" goes down a drastically different path
than most, at least until the very end where a completely unrelated anecdote about
interference with a remote garage door opener is told by Mac. Although the exact
issues chanted by electronics technician cum repairman Barney Gallagher regarding
many manufacturers' penchant for designing and selling unserviceable equipment is
dated, the principle remains the same. We have all wished a designer had to service
the product he/she has designed and sold to us...
 "Ten
U.S. researchers and scientists have reportedly died or disappeared over the past
33 months amid increasing speculation about the cause of some of the disappearances,
according to news coverage. Steven Garcia, a 48-year-old government contractor who
allegedly had top-level clearance at a key nuclear facility disappeared in August
2025 after reportedly leaving behind his phone, wallet and keys, taking a gun and
leaving his home in New Mexico on foot, NewsNation reported Thursday. Moreover,
retired Air Force Maj. Gen. William Neil McCasland similarly went missing on Feb.
27 after leaving his home in Albuquerque on foot, the outlet reported. Eight other
well-known scientists and researchers..."
 For the sake of avid cruciverbalists amongst
us, each week I create a new crossword puzzle. 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 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!
 Here is
Bendix
Models 636A, C, D schematic and parts list as featured in a 1947 edition of
Radio News magazine. No operational or alignment information was provided. The 636A
is a tabletop radio using five vacuum tubes in the detector and amplifier stages,
and a single vacuum tube rectifier in the power supply. Its shiny Bakelite cabinet
sported an Art Deco style, which was popular back in the day. The images to the
left are from a recent eBay listing, for $60, where the seller says it is in working
condition. As mentioned many times in the past, I post these online for the benefit
of hobbyists looking for information to assist in repairing or restoring vintage
communication equipment...
 Johanson Dielectrics has been a worldwide
producer of high quality ceramic chip capacitors for over 60 years. We design and
manufacture capacitors in a state-of-the-art facility in Camarillo, CA. Standard
and high voltage SMT ceramic chip capacitors, as well as a variety of standard and
custom high voltage & high capacitance value ceramic capacitors.
 The 1958-59
International Geophysical Year was an unprecedented eighteen-month global scientific
initiative involving 30,000 participants from 66 nations who invested up to 1.5
billion dollars to study Earth's interior, oceans, and atmosphere. Utilizing military
rockets and emerging satellite technology, researchers achieved major breakthroughs,
most notably Dr. James Van Allen's discovery of the radiation belts surrounding
Earth and enhanced understanding of ionospheric radio propagation, solar flares,
and geomagnetism. While the project aimed to improve communications...
 When I first saw an
Erie Resistor Corporation advertisement in the December 1958 issue
of Popular Electronics, I decided to research its history here in Erie,
Pennsylvania, where I live. Click on that hyperlink if you are interested in what
I discovered. This advertisement appeared in the January 1952 issue of Radio &
Television News magazine, so I figured I'd post it as well...
|
 • Broadband
Equipment Market Set for 2026 Rebound
• Foundry
Revenues to Grow 24.8% YoY
• U.S.
Manufacturing Sector Flexes Its Muscles
• Meta to Ax
10% of Workforce Being Replaced w/AI
• Middle East Conflict
Rewiring Global Supply Chains
 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.
 Atmospheric scientists suspected as recently
as early 1957 that Earth's upper atmosphere (ionosphere
and beyond) temperature might be around 1,000 °K. I say "suspected" because
we had not yet launched instruments there to make actual measurements. Soundly posited
and agreed upon theory was validated a short time later when sounding rockets reliably
reported a maximum of about 1,300 °K in the upper ionosphere. We did not know
for sure what electromagnetic wavelengths and their respective energy densities
would be outside the protective layers of gases encompassing Earth. Much more was
known about the depths of the planet's oceans than of its atmosphere. Scientists
knew that life was abundant below the water's surface but did not know what, if
any, life existed at altitudes any greater than the tallest mountain. Outer space,
devoid of everything we consider essential to support life as we know it, would
be a hostile environment for humans or even electronic instrumentation. It is always
interesting to recall that while you only need to dive 33 feet below the water's
surface to double the ambient pressure, you need to go 18,000 into the atmosphere
to halve the pressure. Beginning in 1957...
 Often I have said I would like to have been
born three decades earlier to have lived during the
golden era of radio and TV, and owned a local service shop. Having arrived on
Earth in 1958, by the time I was old enough to consider electronic servicing as
a career, the industry was in full transition mode to solid state electronics. I
remember the TV repair guy working in our living room with tools and test equipment
spread out on the floor. Growing up in a lower middle class (or maybe it was an
upper lower class) household, our television and radios (both in the house and in
the old 6-cylinder Rambler) used vacuum tubes until sometime in the 1970s. Transistorized
stuff was for the rich folk in the neighborhood over. Upon enlisting in the USAF
in 1978, the air traffic control radar I worked on used vacuum tubes for the primary
airport surveillance (ASR) radar and for the precision approach radar (PAR)...
 Windfreak Technologies is proud to announces
the availability of our
FT108, an innovative
programmable bidirectional filter bank spanning a frequency range of 5 MHz
to 8 GHz in 15 bands. Band selection can be controlled through USB, UART or
at high speeds through powerful triggering modes. Each unit is factory tested via
network analyzer with unique data stored in the device to help with its use. Crossover
frequencies are stored so the user can send a frequency command and the FT108 will
utilizes Intelligent Band Selection logic to automatically toggle the optimal
filter path based on minimum insertion loss. Readback of FT108 insertion loss at
any frequency between crossover points allows for easy amplitude leveling...
 I didn't know that another name for a nomogram
(or nomograph) is an "abac," but thanks to Mr. Crowhust in this 1954 Radio-Electronics
magazine article I now do. At first I thought maybe it was a shortened version of
abacus, but I couldn't find anything suggesting that. Anyway, this article presents
a couple abacs you do not often (if ever) see - the attenuation and reflection levels
for
resistive attenuators when the impedance(s) are incorrect for the designed values.
Keep in mind, particularly when using off-the-shelf components like attenuators,
filters, power couplers and splitters, PIN switches, etc., that if your source and
load impedances are not exactly the same as the component input and output impedance
(usually 50 Ω or 75 Ω), the response will not be as advertised. Achieving
the proper performance will require inserting an impedance matching section...
 In an effort to promote entry of women and
girls into the amateur radio hobby, Short Wave Craft magazine ran a few
contests for
Best "YL" Photos. Amazingly - and maybe there are still instances of it today
- many (if not most) of the YLs featured had built their own equipment. In 1935,
most people built their own equipment, so that is not too surprising. The winner
for this month was a 16-year-old young lady (i.e., "YL") who in fact built her rig.
Another winner was an 83-year-old grandma who was born before Marconi, Maxwell,
and Hertz did their best work! The third winner was a girl who earned her Ham license
at age 6, which back in the day required sending and receiving 5 words per minute
(WPM) in Morse code. BTW, according to the Bureau of Labor Statistics' (BLS) Inflation
Calculator says $5 in 1935 is the equivalent of $94.41 in 2020 money...
 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...
 There was a time that selecting a
television antenna was as important to the quality of life as buying the right
smartphone is today. There were probably as many choices in antennas then as there
are phones now. You might think, especially if you are not an amateur or military
radio operator, that nobody worries about antennas anymore, but as I've written
before there is a slight resurgence in people installing the old fashioned multi-element
antennas for receiving local television and radio stations. The market's not huge,
but seems to be keeping companies like Channel Master in business. Incidentally,
in contrast to my aforementioned comment, dig the opening sentence of the article:
"Virtually no one in this day and age goes about discussing the reception quality
of his telephone..."
 "He no sooner gets alone with a sweater
girl than he's trying to pull the wool over her eyes." That's a really old joke
that only old guys like me remember. "Sweater Girl" was a term
used to describe... how to properly put it... um, you know, the Dolly Parton types...
those who have a good singing voice  . While that is not the
purpose of a sweater girl overtly used in this article from a 1944 edition of
Radio-Craft, you can bet the authors intended the term as an eye-catcher.
I thought you might need to be apprised of the origin of the term to appreciate
the title. You're welcome...
 This is really clever. Appearing in the March
1955 edition of Popular Electronics magazine, "The
Electronic Husband" article is one wife's attempt to quantify her husband's
interest in all things electronic by adapting forms of Ohm's Law to fit observed
behavior. In the process of writing the parody, Mrs. Jeanne DeGood demonstrates
an impressive basic knowledge of Mr. DeGood's second passion (Mrs. DeGood
being his first, presumably). After all the articles that Melanie has proof read
for me, she knows a lot of these equations just as well, even if she doesn't know
what they mean...
 That
ultrasonic communications has not proved to be a reasonable means of transmitting
information from one location to another - even over fairly short distances - is
borne out by the obvious lack of such systems today. With all the technology available
in the form of electronics, mechanics, and software, if it were possible to efficiently
and effectively implement systems of ultrasonic communications, such devices would
be as common as the current plethora of wireless systems. Some early research efforts
at ultrasonic communications were published in a 1945 edition of Radio News
magazine. Regardless of the era, the electromagnetic frequency bands are always
deemed to be too crowded so researchers constantly look for other transmission media.
There is one revolutionary new potential form of remote communications on the horizon:
quantum entanglement. Still largely an enigma, entanglement communications exploits
an observed property of some subatomic particles...
 The "Up Front" page of the May 2022 issue
of QST magazine mentions a musical tribute to ham radio entitled, "Back
on the Air," by Allen Chance (W2BUZ) and Paul Rogers. It has a soothing melody
and the video is accompanied by photos matching the lyrics as it goes along. You
probably have to be a Ham operator to appreciate the message and visuals. A repeating
CW CW CW in Morse code
can be heard in the background. Warning: If you are easily triggered by a couple
"guy" pictures, this video is not for you; please move on...
 The 5-meter band (56-64 MHz) allocated
to U.S. amateur radio operations in the 1930s was reallocated in 1946 to television
broadcasting. However, Hams still are permitted to operate on 6-meter (50-54 MHz)
and 2-meter (144-146 MHz) bands on either side of 5 meters. Therefore, this
1935 Short Wave Craft magazine article on
non-line-of-sight communications within mountainous regions will still be of
interest, even if only from a historical perspective. There is an interesting comment
made about feeding a vertical 1/4-wave antenna from the top rather than from the
bottom (with the entire structure located 50' above the ground). No explanation
is offered as to the reason...
 If the December 13, 1965, edition of
Electronics magazine had a theme, it was undoubtedly reporting on the current
state of
Japanese technology. The cover photo is a shot of a microwave
antennas dominating Tokyo's skyline. Japanese technology companies worked hard to
overcome the largely undeserved negative connotation that a "Made in Japan" label
carried in the day. Do you remember the scene in the movie "Back to the Future Part
III" where Doc, having traveled back in time from the 1950s, is trying to fix his
DeLorean time travel car and discovers a burnt out circuit and claims, "No wonder
this circuit failed, it says made in Japan?" Marty, who travelled from the 1980s,
replied, "What do you mean doc, all the best stuff is made in Japan." There is no
denying the Japanese people succeeded at their goal...
 Robert Balin created many quizzes for
Popular Electronics magazine back in the 1960s and 1970s. This particular "Electronic
Numbers Quiz" presents various objects and your challenge is to match one of
the provided numerical values to each item. For example, a tuning fork is most commonly,
in the Western world, associated with a certain frequency for tuning musical instruments
(electronic and mechanical). As is often the case, being familiar with the "standards"
of the era is helpful on a few of the items like the tuning capacitor and the IF
transformer, but you should be able to eliminate some options by knowing the impedance
of the twin lead transmission line and the phase relationship of current and voltage
in a pure inductance...
 I am always amazed when reading articles
like this one on "The
Art of Xerography" at how the engineers and scientists who develop these system
manage to think up the processes and materials required to make everything work
so well, and then to make it manufacturable on a mass basis. How did Chester Carlson
discover that dyed lycopodium powder, made from creeping cedars, sprinkled over
a waxed paper plate would create the likeness of an original image - after, of course,
rubbing a sulfur-coated metal plate with a handkerchief and quickly exposing the
plate to light transmitted through the glass with a pattern on it? Electrostatics
eventually came to play a big role in high volume printing, as described here. I
saw a video one time (can't find it now) of a high voltage and chemical processed
used on thin aluminum sheets used in newspaper printing up through the 1970's for
making masters. My father worked at The Evening Capital newspaper in Annapolis,
Maryland, and I remember back in the 1960's walking through the printing press area
and seeing operators pounding away on typesetting machines that assembled the lead
die into lines of text, and from there the entire process up through actual printing
and folding of the newspapers. From around 1970 through 1974, I delivered those
papers in my neighborhood on my bicycle. The subscription cost was a whopping $2.10
per month...
 JP Wilson ran across my list of fellow USAF
radar maintenance techs (AFSC 303x1), and graciously provided this photo of the
MPN-14(G) mobile radar control center he worked on at Zaragoza AB, Spain, in the
late 1970s. Interestingly, one of my Keesler tech school classmates,
Jim Flinn, was his replacement
at K.I. Sawyer AFB, Michigan, in 1979. If you were - or still are - a USFA
Radar Shop tech and would like to be added alongside your comrades, please send
me an e-mail with your
service info. Equipment photos are especially welcome since people love seeing
reminders of their past - an era when everyone wasn't running around with a camera
in a cellphone...
 Meteor scatter (aka meteor burst) communications
is today largely the domain of amateur radio operators in their ongoing attempts to set
records for making long distance (DX) contacts with a minimum amount of transmit power.
When this article was written by U. California's Victor Latorre, transcontinental fiber
optic cables did not interconnect the world with high speed, phase stable media that
meets the exacting needs of precise time synchronization. Radio astronomy, quantum physics
experiments, and even stock market trading depends on microsecond or finer timing. Mr. Latorre
mentions here about using
meteor scatter communications' unique phase-stable characteristic to send
synchronization signals between scientific and navigation facilities. Of course
meteor scatter has the severe disadvantages...
 RF Cave visitor and contributor Joseph Birsa
(N3TTE), sent me a note about yet another edition of a special purpose catalog published
by Sears - the
Sears 1940 Amateur Radio, Test Equipment, Sound System Catalog. A little research
revealed that it was actually an extended version of the 1940 Sears, Roebuck and
Co. Superior Amateur Equipment and Radio Service Supplies - 64 versus 48 pages,
respectively. Even the standard edition Sears, Roebuck Fall 1941 Catalog contained
a large section dedicated to radios and equipment. The cover on the shorter catalog
makes me think of The Radio Boys series of books, where a cadre of four early 20th
century teenagers experienced adventures centered around building and operating
wireless equipment. Hallicrafters, National Company, Meissner, and Hammarlund receivers
and transmitters were offered for sale. Bliley and Silvertone...
 This 1957 Radio & Television News
magazine article purposes to set the record straight about the difference between
John A. Fleming's "thermionic
valve diode" rectifier, which did not produce signal amplification, and de Forest's
Audion tube, which did provide amplification. U.S. patent number 841387, "Device
for Amplifying Feeble Electrical Currents," was issued to Lee de Forest on January
15, 1907, a little over a year after Fleming received patent 803684 for his "Instrument
for Converting Alternating Electric Currents into Continuous Current" on November
7, 1905. Unlike the contest between pro-Wright and pro-Whitehead camps who debate
which party/parties achieved the world's first manned flight which took off under
its own power, the record is very well documented regarding invention of the electronic
amplifier... |
