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 The
1-dB compression point, usually written P1dB, is a practical large-signal linearity
limit for RF and microwave components such as low-noise amplifiers, power amplifiers,
mixers, active frequency multipliers, driver stages, variable-gain amplifiers, attenuators,
limiters, isolators, filters, switches, and receiver front-end modules. It is the
input or output power level at which the measured gain has fallen 1 dB below the
gain predicted by the small-signal linear gain line. In symbols, if the small-signal
gain is GSS in dB, then at the 1-dB compression point: Pout(measured,
dBm) = Pin(dBm) + GSS(dB) - 1 dB When the input power at that condition
is quoted, it is called input...
 Anytime I see an airplane in a photograph,
my interest is immediately piqued to learn the story behind it - sort of like with
the "MPATI - Its Problems & Solutions" feature in the May 1963 edition of
Electronics World magazine. This "Aerial 'Private Eye' Traces TV Signals" story also involves
airplanes and television broadcasting, albeit in a completely different way. A couple
enterprising broadcast engineers created a company called Tele-Beam Industries,
in Napa, California, that measured and mapped TV signal strength in the region surrounding
transmission towers to provide the stations with information useful in marketing
and radiation characteristic planning. Signal strength...
 Two major radio events were covered in this
1954 issue of Radio & TV News magazine's monthly "Spot Radio News"
column - the rapid advance of microwave technology for building out
high capacity voice and television transmission systems, and the
ever-increasing number of new TV station operation license grants since the ending
of the Federal Communications Commission (FCC) moratorium in 1952. In 1944, the
FCC stopped issuing broadcast permits due to serious unforeseen interference from
co-location interference issues as post-war households enthusiastically adopted
TV. Unlike today's microwave relay networks, in the 1950s most systems were
still analog in nature. Coaxial...
 The first video below is my favorite. It
is a one-minute clip from a 1960s episode of "The
Twilight Zone" television show. It is an outrageous slam on amateur radio operators
by a family whose radio and TV shows are being interrupted by interference. Dad
looks out the window and sees what are actually television antennas on the guy's
roof and when Mom asks if there is anything they can do about the neighbor, he walks
toward the telephone saying he can at least check to find out whether neighbor man
has a license to operate. Mom then says, "Do you think you should, Stu? Those men
seem kind of...threatening somehow." Those d**n evil Hams! As you might expect if
your are familiar with the series...
 Empower RF Systems announces the release
of its new
Model 1240, a compact, high-performance RF amplifier module delivering a guaranteed
minimum of 200 watts across the 900-1700 MHz frequency range. Designed to address
the evolving demands of modern electronic warfare (EW) and counter-unmanned aerial
systems (C-UAS), the Model 1240 expands Empower RF's portfolio of tactically deployable,
high-reliability solutions. The Model 1240 is a full gain "smart module" built on
advanced GaN transistor technology, integrating comprehensive control and monitoring
features to ensure consistent RF performance under all environmental conditions.
What sets the Model 1240 apart is its strategically targeted frequency coverage.
The 900-1700 MHz range aligns...
 Pulse compression (aka "chirp") radar was invented in the 1950s by Sperry and a couple
other defense contractors. It was new enough by the time the radar I worked on as
a technician in the USAF that it was not incorporated. Our MPN-13 and MPN-14 radar
systems used simple single-frequency pulses. Pulse compression employs a swept frequency
within a fairly narrow bandwidth to exploit the benefits outlined in this 1965
Electronics World magazine article. If you were to listen to the signal
used to sweep the RF pulse in frequency, it would sound a lot like a bird's chirp,
hence the name. Treatment by author Donald Lancaster is fairly heavy in that it
fearlessly presents the mathematical...
 Raise your hand if you have ever owned a
CB (Citizens Band) radio. Waaaaay back before everyone carried a cellphone (pre-late-1990s),
the most common form of
unlicensed communication was CB radio. Actually, up through the
mid 1970s you were supposed to purchase a license from the FCC, although no test
was required as it was for amateur radio. My first CB was a 23 channel job that
I installed in my 1969 Chevy Camaro SS, during my senior year in Southern Senior
High School. It was right in the middle of big CB radio craze with CW McCall's
"Convoy" song topping the U.S. Billboard charts. My self-appointed 'handle'
was "RC Flyer." Most people had no idea what it referred...
 Admittedly, with all the reading I have
done of vintage electronics magazines, news of this
Crystron (crystal-electron) vacuum tube device invented by Mr. Mohammed
Ulysses Fips, as reported in the April 1947 issue of Radio Craft magazine,
evaded my attention. The article came only a couple months after publication of
the 40th anniversary edition that celebrated Dr. Lee de Forest's invention
of the Audion tube. According to Mr. Fips, his Crystron one-upped the Audion
by virtue of its containing a small amount of radio isotope which obviated the need
for the traditional "B-battery" concept also developed by de Forest to supply
a high voltage for driving the output stage circuit...
 On July 14, 2026, the U.S. Congress voted
to
make Daylight Saving Time (DST) permanent, thereby eliminating the biannual
clock change routine. Daylight Saving Time (DST) is the practice of advancing civil
clocks by one hour during part of the year so that more daylight falls in the evening.
In the U.S., DST has been used intermittently since WWI, standardized nationally
in 1966, and briefly tried as a near-permanent winter policy during the 1974 Oil
Embargo / Energy Crisis (which was such a disaster it was repealed in less than
a year). The Emergency Daylight Saving Time Energy Conservation Act of 1973 put
most of the country on year-round DST beginning January 6, 1974. The idea sounded
attractive: an extra hour of daylight after work and school, but the public quickly
discovered...
 Sam Benzacar, of Anatech Electronics, an
RF and microwave filter company, has published his June 2026 Newsletter that, along
with timely news items, features his short op-ed titled "Overlooked, Not Obsolete:
CB Radio at 27 MHz." Being "old" myself, the bit of nostalgic nearly brought
a tear to my eye. Having "come of age" myself in the 1970s, I was quick to jump
onto the CB radio craze, installing my first 23-channel rig under the dash of my
1969 Camaro SS hot rod. Every guy I hung out with knew all the words to C.W.
McCall's "Convoy" hit song. ...but I digress. Sam points out that while CB radio
is not the hot item is was decades ago, niche groups still occupy the band in number
large enough for the FCC to not reallocate the frequencies to paying clients...
 Welcome to the RF Cafe
Coaxial Connectors
Quiz, an essential module for any engineer or radio hobbyist focused on maintaining
interconnect integrity across their signal chain. Whether you are standardizing
your station hardware, troubleshooting high-frequency signal leakage, or verifying
the physical port interfaces for your test bench equipment, a thorough understanding
of coaxial connector characteristics - from the rugged reliability of the Type N
to the precision of the SMA - is vital. This assessment challenges your proficiency
in connector selection, exploring the differences in mating mechanisms, cutoff frequencies,
constant-impedance geometries...
 This installment of the multi-month series
of articles on antenna principles covers
directional arrays for 300 MHz and higher. Keep in mind that
in 1947 when this appeared in Radio-Craft magazine, wavelengths of a meter
or less were considered to be at the upper end of the operational range. Parabolic
reflector antennas were the domain primarily of ground-based installations due to
the physical size and weight being prohibitive in airborne platforms, and even then
they were rarely used at the time. Most ground and airborne installations were composed
of dipole antennas with various configurations of reflector and director elements
for desired gain and directivity characteristics. Special...
 Echo 1 launched in August of 1960,
finally allowing America to participate in the Space Race, which until then was
roundly being won by the USSR. Electronics magazines of the day were filled with
prognostications of the future of
space communications. Electronics World dedicated most of their
November issue to satellite Earth stations and advancements being made in ultra
sensitive receivers and powerful transmitters. Since the earliest satellites were
literally metallic balls for reflecting radio signals, it was necessary to optimize
both ends of the communications path since there were no circuits onboard the satellite
to perform signal processing and re-transmission. Bell Labs, of course, was at the
forefront...
 As with many relatively new technologies,
the
exuberance over radio peaked quickly once the benefits of communications
over long distances without the need for wires was realized by the public. After
a couple decades a lot of "authorities" began pontificating about how all the useful
applications of radio waves had been discovered and that any new innovation would
be merely incremental improvements in existing technology. Novel circuits for minimizing
static over the radio or maybe building more powerful transmitters for longer range
were the only concepts within reach of their limited imaginations. Similar phenomena
occurred for those who thought airplanes would always have...
 The Klondike / Yukon Gold Rush is generally
credited with opening up the Alaskan territory to exploration and habitation. Gold
was first reported in August of 1896, just three decades prior to this advertisement
in a 1931 issue of QST magazine by the
De Forest Radio Company extolling its domination of the region
with radio communications stations. Company founder Lee De Forest was very
successful in exploiting the virtues of his famous Audion amplifier tube. A back-handed
swipe is taken at Government installations that used "whatever tubes the Government
has...
 Fixed-value resistors are among the simplest-looking
components in electronics, but their development reflects nearly the entire history
of electrical science, telecommunications, electric lighting, industrial power,
radio, military electronics, printed circuits, hybrid microelectronics, and surface-mount
manufacturing. Partly out of curiosity of how extensive, comprehensive, and accurate
an AI-generated report on topics of science and engineering, I instructed ChatGPT
to generate the following thesis titled
History of Fixed-Value Resistor Electronic Components. Most useful AI interactions,
I have found, require more than one input...
 Since we seem to be on a roll of FM radio
theme articles printed in vintage electronics magazine, here is one from a 1973
issue of Popular Electronics magazine. The author never explicitly tells
us the date when the Institute of High Fidelity (IHF) updated its
FM tuner specifications, and neither does he mention groundbreaking
work of IHF's Julian Hirsch, who is largely responsible for both the initial and
updated standards. If you read magazine stereo equipment reviews in the 1960s and
1970s, then you probably recall the name. Anyway, this article discusses the improved
specifications made possible by more sophisticated circuits made possible by semiconductors
and miniaturized...
 Comics in modern magazines are a rather
rare phenomenon for some reason, but they were fairly regular features up until
a couple decades ago. This set of
comics from the July 1963 edition of Popular Electronics
magazine deals with high fidelity (Hi-Fi) stereo equipment, which was considered
somewhat exotic and high-end for many people's budgets in the day. Inexplicably
(not), that is about the time that increases in hearing losses among younger people
were first being noticed in audiograms. I listened to my share of loud music beginning
in the late 1960s, and operated many model airplane engines and lawnmower type engines
my whole life, and still, at 68 years...
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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.
 The fundamentals of
Class-B push-pull amplifiers have not changed since 1960 when this article appeared
in Electronics World magazine. The transistors for making them have improved
in most cases, but the design procedures are basically the same. Class-B amplifiers,
in case you are not familiar with the topology, are able to amplify zero-referenced
sinusoidal signals throughout the full 360 degrees of rotation signals without an
offset voltage bias; they are constructed from two Class-A amplifiers in a cascode
configuration. Issues like crossover distortion and thermal runaway are discussed
in the amplifier design procedure...
 Dealing with on-site traveling salesmen has
always been a sort of love-hate (or maybe a necessary evil, to put it less extremely)
relationship - for both the salesman and the engineer/technician. Not having been
in the engineering design environment for nearly two decades, I don't know how much
face-to-face contact is made anymore. Up through the early 2000s, I was still occasionally
meeting with components salesmen. In this June 1952 issue of Radio & Television
News magazine's
Mac's Radio Service Shop technodrama, proprietor Mac McGregor takes the occasion
of an afternoon rain torrent to discuss the situation with two of his regular sales
representatives...
 Navy Electricity and Electronics Training
Series (NEETS) Module 4 -
Introduction
to Electrical Conductors, Wiring Techniques, and Schematic Reading. Upon completing
this chapter, you should be able to: 1. Recall the definitions of unit size, mil-foot,
square mil, and circular mil and the mathematical equations and calculations for
each. 2. Define specific resistance and recall the three factors used to calculate
it in ohms. 3. Describe the proper use of the American Wire Gauge when making wire
measurements. 4. Recall the factors required in selecting proper size wire. 5. State
the advantages and disadvantages of copper or aluminum as conductors. 6. Define...
 Even though this CW (continuous wave, for
sending Morse code)
transmitter circuit was published in 1955 in Popular Electronics magazine,
it is still legal for today's Amateur radio operator. Portions of the 40-meter and
80-meter bands are still reserved exclusively for CW operation. As of 2021, the
40-meter band (7.025-7.125 MHz) and the 80-meter band (3.525-3.600 MHz)
are both reserved for CW for Hams holding either Novice (no longer issued) or Technician
licenses. Additionally, the 15-meter band (21.025-21.200 MHz) and the 2-meter
band (144.0-144.1 MHz) have CW-only areas. That is different than the frequencies
given in the article, so beware if...
 In this 1946 issue of Radio-Craft
magazine, editor and über electronics guru Hugo Gernsback reviews "Secret
Communications" methods used throughout history, including Alexander Graham
Bell's "Photophone" that used a modulated light beam for transmission. With World
War II having recently ended and devices such as the "Enigma Machine" developed
by the Germans for secure encryption of messages, secure communications was high
on the priority list of government and military strategists. Gernsback also suggests
ultrasonic systems for wireless communications, and a multiple channel scheme suggestive
of the m-ary method widely used today...
 This was a multi-part series published by
Radio & Television News magazine in the days when
color TV was the domain of the more well-to-do folks on the block. Needless
to say (but I'll say it anyway), nobody I knew had color TV before around 1968.
One of my friend's father owned a fairly profitable gas station and service garage,
so they were the first to have one. For some inexplicable reason (I jest), his mother
never allowed more than one or two of us into the house at a time, so we drew straws
to see who got to witness that fabled miracle of technology. I was about third in
line. Insomuch as the 1960s were a much more polite and private time than the...
 Thanks to a tip by RF Cafe visitor and contributor
Bob Davis for letting me know about a very capable point-to-point
RF system planner called Radio Mobile (URL updated since original expired),
by Canadian Ham radio operator Roger Coudé (VE2DBE). There is another similar freeware
program available called AlphiMax, but it requires that you upload your system data
to a remote server - a potential confidentiality conflict. Radio Mobile uses GPS-based
terrain information obtained from the U.S. Department of Commerce NTIA/ITS Institute
for Telecommunication Sciences Irregular Terrain Model (ITM) database...
 Although not directly applicable today, these
charts from a 1952 issue of Radio & Television News magazine showing
signal voltage levels versus distance from broadcast television transmitter
locations provide a general sense of how attenuation varies as a function of distance.
Both low (channels 2-6 at 54-88 MHz) and high (channels 7-13 at 174-216 MHz)
VHF bands are included for a couple different standard power levels. A Transvision
Model FSM-1 field strength meter (see example at left) was used to construct these
charts. While the Friis equation for signal free space attenuation can be used to
predict levels, actual physical measurements are often...
 Here is an easy-to-build project that demonstrates
how like electrical charges repel. The
electroscope was developed by English physicist William Gilbert in 1600. I remember
playing with one in physics class in junior high school (one of the few classes
that interested me at the time). The electroscope in this 1955 Popular Electronics
magazine article calls for the use of gold leaf, but it can be any type of good
electrical conductor. In fact, I found a video on YouTube that shows how to make
an electroscope out of commonly available materials. This would make a good conversation
piece to sit on your desk...
 I have been scanning and posting many "Radio
Service Data Sheets" like this one featuring the
Arvin Model 6 under-dash car radio in graphical format, but have not yet
run OCR on them to reproduce the textual content for search purposes. Radio-Craft
magazine and others published many of these for the sake of hobbyists and commercial
repair shops that could not afford to pay for subscriptions to services such as
Sams Photofact. I could not locate an example of a restored model. Manufacturers
usually would not provide service data to non-representatives. There are still many
people who restore and service these vintage radios, and often it can be difficult...
 This is another Radio Service Data Sheet
that appeared in the March 1936 edition of Radio-Craft magazine. I post
this schematic and functional description of the
Belmont Model 578 Series A, 5-Tube A.C. Superheterodyne radio manufacturers'
publications for the benefit of hobbyists and archivists who might be searching
for such information either in a effort to restore a radio to working condition,
or to collect archival information...
 Have you noticed how
heavily burdened utility poles (formerly referred to as electric poles or telephone
poles) are these days? Many of the decades-old creosoted wooden poles originally
were designed to carry a single set of high voltage distribution lines (13.8 kV)
and a multiconductor telephone cable containing twisted pairs. Look around now and
you will see at least twice that number of cables, and often three times as many
due to multiple coaxial and fiber optic cables and needing to route extra AC power
circuits (of larger gauge to handle higher current) in increasingly crowded areas.
Notice how many are leaning over (particularly at corners) and/or are being supported...
 Probably when you think about vacuum tubes,
you envision the short type that plugged into your (or your parent's) TV set or
radio. While they were sophisticated in their own way and also required careful
assembly with a lot of manual operations, these high power tubes were in a class
of their own. Even the one in this article from the April 1959 Popular Electronics
magazine is not as complicated as some of the ones designed and built for high power
radar systems. As always, it is interesting to note the lack of eye protection during
assembly operations, especially given that the glass could easily shatter at any
point. I'm guessing that the guy in Figure 1, doing the glass...
 These "Radio
Term Illustrated" and "Technical Term Illustrated" electronics-themed comics
are amongst the best I can remember seeing. They appeared in two 1946 issues of
Radio-Craft magazine. For the uninitiated, WAVES is an acronym for Women Accepted
for Volunteer Emergency Service. They were a World War II phenomenon established
on July 30, 1942, half a year after the Pearl Harbor attack. Their Navy Reserve
status granted both commissioned officers and enlisted women official service duty
status for the duration of the war and entitled them to the privileges (and in some
case dangers) that came with it. As with women occupying...
 This
Technical Themed Crossword Puzzle for October 10th has many words and clues
related to... you guessed it... engineering - including RF, microwave, 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., Hedy Lamarr or the Bikini Atoll). The
technically inclined cruciverbalists amongst us will appreciate the effort... |
