|
 You will love the irony at the end of this
Carl Kohler technodrama. It appeared in the June 1957 issue of Popular Electronics
magazine. I'm not going to spoil it by even hinting at the conclusion - only that
the story follows the familiar path of the dauntless husband-electronic-hobbyist
taking off on another of his somewhat hair-brained ideas, while "friend-wife" looks
on. Her self-restraint is tested, as usual - although she jabs with some uncharacteristically
harsh zingers this time. Have you noticed how men are expected to be self-deprecating
in situations in order to create humor? The technology here was considered bleed-edge
back in the day. BTW, I fed the husband's humor bait to AI and it came up with some
pretty good responses - like what had been expected by him. AI came up with
a long name for FUNIAC (clearly a play on names like UNIVAC and ENIAC)...
 "The Whistler
and His Dog" is one of those tunes that you have probably heard dozens of times
but never knew the title of it (video at bottom of page).
It is mentioned in this installment of "Mac's Radio Service Shop" from a 1948 edition
of Radio & Television News magazine. Barney is said to have been whistling
it while replacing an output transformer on a receiver-recorder... a wire recorder
at that. The "20 Questions" theme is from the game where the player attempts to
guess the answer by asking a series of questions that narrows the possible results
until only the correct one is left - aka deductive reasoning. BTW, I'll bet "The Syncopated Clock" is another tune you've
heard many times but didn't know the title of it...
 Have you noticed how many wooden utility
poles are
bending under the load of communications cable weight they were never designed
to withstand? Some are ridiculously burdened - and it is not "engineered deflection"
for line tension changes. Power companies want to charge the communications companies
for pole and/or cross bar replacement and/or upgrading, but the FCC just ruled that
pole owners cannot charge the full cost of replacement. That financial deficit,
of course, gets passed on to electric power customers. You wonder why your monthly
bill has skyrocketed in the last few years? That is part of it - along with
us peoples subsidizing wind and solar generation, and paying for free Internet and
cellphones to half the population (including Illlegals). Do you fell violated? I
do.
 Radio-Craft magazine solicited inputs
from its readers for a series of "Radio
WittiQuiz" questions and answers related to radio and electronic, with a stipulation
being that there had to be some aspect of humor included. That meant that some of
the multiple choice answer options needed to be inane. For most of the questions,
the process of elimination is pretty easy, but a couple could cause some head scratching
- especially if you are not really sure of the answer. This group starts at number
28, so obviously preceding issues had questions 1 through 27. At some point I will
probably acquire them and post other Radio WittiQuizzes...
 Having never been a sports aficionado, I
have not spent much money or time at baseball, football, or soccer fields, hockey
rinks, bowling alleys, curling sheets, or basketball courts. When an air show comes
to town, however, I'm there. I'll stand in line for 45 minutes to tour the inside
of a DC-3, B-25, B-17, PBY-5, or just about anything that will admit me. What is
particularly enjoyable is inspecting the radio equipment racks and bays. The sight
and smell (I consider it an aroma) of the old UHF
and VHF sets, recording equipment, power supplies, generators, synchros, and the
associated wiring and connectors is something I never tire of experiencing. I always
imagine the men who operated and maintained everything doing their assigned duties
to keep those wonderful machines flying...
 The
Chronistor, which appeared in a 1958 issue of Popular Electronics magazine,
was a compact elapsed time indicator in the form of a common glass fuse. Powered
by electroplating, it requires roughly 1 mA of DC current to migrate metal
ions from anode to cathode via an electrolyte, resulting in visible cathode deposition
along a glass-printed hour scale. Standard options included 500, 1000, or 2500-hour
ranges, with specials (like a 1-year, 8760-hour version) from Bergen Laboratories.
The article outlines a basic series circuit for AC line operation, comprising a
half-wave rectifier, pilot lamp, and limiting resistor for the Chronostat...
 If
you have kids, you'll probably appreciate these two
comics that appeared in the May 1956 issue of Young Men • Hobbies • Aviation
• Careers magazine. Young Men was a fairly short-lived publication,
having existed for only a couple years around the 1956 timeframe. It was not affiliated
with the Academy of Model Aeronautics (AMA), which had its own series of magazines.
Howard McEntee, famed radio control pioneer, was on the staff, and Albert L.
Lewis was editor. Unlike the other aviation magazines of the day, Young Men covered
a broad range of activities and hobbies including model boating and cars, electronics,
chemistry, physics, school, amateur magic tricks, shooting, and more.
 "Google's parent Alphabet has reached a
definitive agreement to
acquire renewable energy developer Intersect Power for $4.75B, a transaction
that signals a structural transformation in how Silicon Valley intends to power
the AI era. By owning a power utility, Google can secure energy for its data centers
directly. This acquisition marks a departure from the industry's decade-long standard
of signing Power Purchase Agreements, where companies contract for energy from third-party
developers. Instead, Google is taking ownership of a 3.6-GW pipeline of late-stage
solar and wind projects, along with 3.1 GWh of battery storage..."
 Well... it was 50 years ago referenced to
the year this story was published in 1937. That makes it 138 years ago referenced
to 2025. The story's point is that half a century had passed already since the confirmation
of existence of electromagnetic waves as proposed by James Clerk Maxwell.
Heinrich Hertz's "Funken-Induktor" (spark inductor) and his "Knochenhauershen
Scheiben" (Karl-Wilhelm Knochenhauer's disk-type capacitors) were key to his ability
to generate, transmit, and receive EM energy. The work originated from attempts
to prove that light was a form of electromagnetic waves...
 Before the advent of companies like Sam's
Technical Publishing information packets, it was often impossible to obtain schematics
and service information from manufacturers unless you were a certified service shop
and/or dealership. In response to many inquiries from Radio-Craft magazine's
readers, publisher Hugo Gernsback queried the
top manufacturers of the day to determine their policies for distributing such
data. Unlike the last couple decades, procuring service information on commercial
products could be very time consuming, and often resulted in not even obtaining
what you needed. Thanks to the Internet being populated with schematics and mechanical
drawings for seemingly everything ever made, we no longer need to call or mail order
for information needed to repair your radio, television, cellphone, lawn mower,
toaster...
 Werbel Microwave began as a consulting firm,
specializing in RF components design, with the ability to rapidly spin low volume
prototypes, and has quickly grown into a major designer and manufacturer with volume
production capacities. Our
WMC-0.5-20-30dB-S is a wideband 30 dB power coupler is a wideband 4-way
in-line power splitter covering 500 MHz to 18 GHz with very good return
loss, low insertion loss, and high isolation performance. The device covers military
bands C through J (upper UHF band, L, S, C, X, Ku, and K bands), delivering much
value to the program. No Worries with Werbel!...
 A lot of the guys I knew from my time in
the U.S. Air Force as an Air Traffic Control Radar Repairman (AFCS 303x1) went to
work for the government or defense contractors after separation. Many were retirees,
so they were (are) collecting military retirement pay on top of really good pay
doing field service work. At this point, probably most of those guys are now doubly-retired,
and collecting Social Security. They're living pretty well these days, probably
with nice homes paid off long ago. 1957, the year this solicitation for
field engineers appeared in Popular Electronics magazine, was right
at the end of the Korean War, and only a decade after World War II. A lot of
new equipment was designed and delivered...
 While working as an electronics technician
at the Oceanic Division of Westinghouse in Annapolis, MD, in the 1980s, I received
a vintage 1941 Crosley model 03CB console style radio for Christmas from Melanie.
It was in poor condition, having spent the previous few decades sitting in a barn
on the Eastern Shore of Maryland. Due to the era of manufacture, vacuum tubes rather
than transistors provided all the necessary amplification. One of the engineers
I worked for at Westinghouse (Mr. Jim Wilson, engineer extraordinaire)
was a Ham radio operator and had been from boyhood in Pittsburgh, PA. After learning
of my Crosley, he gave me his
B&K Dyna-Quik Model 650 tube tester for use in restoring the
radio. The Model 650 was a rather high-end portable tube...
 "Firefly Aerospace's Blue Ghost Mission
2 with the LuSEE-Night radio
telescope aboard will attempt to become the third successful mission to land
there. The moon's far side is the perfect place for such a telescope. The same RF
waves that carried images of Neil Armstrong setting foot on the lunar surface, Roger
Waters's voice, and hundreds of Ned Potter's space and science segments for the
U.S. broadcast networks CBS and ABC interfere with terrestrial radio telescopes.
If your goal is to detect the extremely faint and heavily redshifted signals of
neutral hydrogen from the cosmic Dark Ages, you just can't do it from Earth..."
 In the early days of television, what we
today refer to as cathode ray tubes were called
kinescopes. The kinescope on the receiving end displayed images generated
by a tube called an iconoscope on the transmission end. Kinescopes had round faces
onto which a rectangular picture was electronically drawn. Once manufacturing technology
evolved sufficiently, it became possible to make them rectangular in order to save
on material and to fit a larger picture in a smaller area. The real story as told
in this 1947 Radio News magazine article from my perspective is appreciating the
ingenuity of the manufacturing engineers for an ability to develop machines that
handle very complex operations. They were wonders of electromechanical manipulation.
Oh, and I learned a new word - "lehr"...
 This Radio Service Data Sheet for the
Sparton Model 40 6-Tube T.R.F. Automotive Receiver is an example
of the dozens of similar schematic and alignment instruction sheets that have been
posted on RF Cafe over the years. Obtaining technical information on most things,
even readily available items, prior to the Internet era was often very difficult
- if not impossible. Service centers had what was need provided by manufacturers
and distributors, but if you wanted to find a part number or service data on a refrigerator,
radio, lawn mower, garage door opener...
 Here is a great primer on the operation
of
traveling wave tubes (TWT). A controversy exists over who first invented the
TWT - Bell Telephone Labs' Dr. Rudolf Kompfner, or Andrei Haeff while at the Kellogg
Radiation Laboratory at Caltech. Regardless of its provenance, the device was a
major advancement in the development of high power microwaves. A TWT amplifies broadband
microwaves continuously: an electron gun emits a high-speed beam through a vacuum
tube, interacting with the weak input signal propagating along a helical slow-wave
structure. The helix slows the signal's phase velocity to sync...
 Take a break from workaday drudgery by trying
your hand at this week's
Amateur Radio crossword puzzle. Every word in the RF Cafe crossword
puzzle contains the usual collection of science, math, and engineering terms, and
also includes special words related to Amateur Radio (clues labeled with asterisk
*). There are no generic backfill words like many other puzzles give you, so you'll
never see a clue asking for the name of a movie star or a mountain on the Russia-China
border. You might, however, find someone or something in the otherwise excluded
list directly related to this puzzle's technology theme, such as Hedy Lamarr or
the Bikini Atoll, respectively. Enjoy.
 "Advanced threats lead to open architecture
approaches and new
analysis of electronic countermeasures. Over the past decade, preeminent countries
involved in major military conflicts mainly focused on asymmetrical warfare - surprise
attacks by small groups armed with modern, high-tech weaponry. During that same
period, however, near-peer adversaries began attaining impressive electronic warfare
(EW) capabilities. As a result, a plethora of new, dynamic threats flooded the EW
spectrum, pushing threat detection and analysis to keep pace. Large military forces
must now engage in ongoing..."
 Here are a couple more electronics-themed
comics from Electronics World magazine, good for winding down the week.
They appeared in the January 1963 issue. The page 86 comic reminds me of the professor
I had for solid state circuit design. He was supposedly the first person to successfully
use gallium arsenide (GaAs) as a semiconductor, although he also did pioneering
work with silicon. Anyway, Prof. Anderson would say he takes at least one "business"
trip each year to Portugal in order to search for higher quality raw semiconductor
material in sand on the beaches. He spoke Portuguese, BTW. The page 89 comic is
reminiscent of the pre-GPS days of navigation. Raise you hand if you ever drove
around utterly lost while looking for an off-the-beaten-path location...
 In the mid 1930s, hand-assembled products
were by far the rule rather than the exception for most products be they electronics,
furniture, appliances, automobiles, or toys. Many people lament - even curse - the
advent of machine automation in production, but the fact is for the vast majority
of things the consistency and quality of the finished component is typically much
greater. Toiling at the same task, in the same location, day after day, gets unbearable
very quickly for someone like me who likes to accomplish a particular job and then
move on to something new - even if "new" is defined as the same type of endeavor
but with different materials. There are many people, thankfully...
 At Parvoo University, amid relentless November
rain, H-3 dormmates Carl and Jerry pursue H-2's prank: a stolen bronze trophy plaque
hurled into a half-mile muddy stretch of river. Cold, turbid waters bar preclude
dives for a search; non-magnetic bronze defies current-day metal detectors. Jerry
repurposes his cousin's boat depth-finder as an
enhanced sonar, exploiting echo signatures. A motor rotates a neon tube across
a depth-calibrated dial; at zero, contacts trigger a 200-kc ultrasonic pulse from
the transducer in transmit (speaker) mode, flashing initial glow. Bottom echo reflects
to transducer in receive (microphone) mode, amplifying...
 The announcement and public demonstration
of Senatore Guglielmo Marconi's "death ray" device was the coming true of some of the worst fears
of science fiction aficionados. Application of these newly created centimeter wave
"beams" could roast the flesh of man or beast when generated with great enough power.
The diminutive wavelength not only would heat liquids, but also provided a means
of detecting and measuring energy reflected off of "targets" such as aircraft and
boats. It applications were endless. Although not called so, one of the article's
diagrams looks to be an example of a bistatic radar system. The early magnetron
implementation is quite different...
The Federal Communications Commission (FCC)
is looking for qualified applicants for
Field Agents in seven Enforcement
Bureau (EB) offices across the United States: Atlanta, GA; Boston, MA; Chicago,
IL; Dallas, TX; New Orleans, LA; New York, NY, and Portland, OR. Incumbents will
resolve Radio Frequency (RF) interference, educate users, and enforce regulations.
The GS levels for this position have been expanded to GS 7, opening the opportunity
for new college graduates. One year of work experience is not required for this
position. Closing date is March 2, 2026...
 If you are from a family of electronics
hobbyists and/or professionals, then there is a good chance your grandfather and
possibly even your father kept a handy-dandy list of common
circuit design formulas handy. Part 2 of the list appeared here in a 1930 issue
of Radio-Craft magazine. All the formulas on this page dealt primarily
with vacuum tubes, the schematics for which were presented in Part 1 of the series.
There are still lots of hobbyists who restore and/or modify vintage sets, so the
equations are still worth publishing. There was not an "app for that" back in those
days. Prior to a smartphone in every pocket, notes were pinned to a lab wall or
kept in a hand-written notebook...
 The name
Frank Conrad probably does not sound familiar to most people in
the electronics communications field today, but at one time he was the assistant
chief engineer to the Westinghouse Company. Back when voice radio (as opposed to
Morse code, aka CW) was being pioneered, Mr. Conrad was widely known for his efforts
in commissioning the country's first commercial broadcast installation - KDKA in
Pittsburgh, Pennsylvania. His arranging for live coverage of election night results
in 1920 is credited for launching a huge interest by consumers in purchasing radio
sets for their homes (Warren Harding beat James Cox that night, BTW). Toward the
end of his career, Conrad was active in helping develop...
|
 • FCC Gives
Amazon OK for 4,500 More Satellites
• China
Memory Producers Race to Exploit Shortage
• U.S.
Manufacturing Sector Returns to Growth
• ARRL
Student Coding Contest $25k Award
• Shielding
Electronics Supply Chain from Cyberthreats
• Fund Opens
Defence Contracts to UK Startups
 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.
 Here are a few more
electronics conundrums with which to exercise the old noodle. These are puzzlers
from a 1959 issue of Popular Electronics magazine, but at least one of
them (#4) will likely prove to be a real stickler unless you have seen a similar
resistor mesh problem before (see my solution for the resistor cube equivalent resistance).
There are no tube circuits to use as an excuse for not attempting them - just resistors,
batteries, switches, meters, a motor, and a couple light bulbs. All four would be
fair game to present to an interviewee to see where he/she stands on basic circuit
analysis...
 Raytheon is another of the stalwart
early American electronics and technology manufacturing company. It began
operations in Cambridge, Massachusettes in 1922 under the name of the American
Appliance Company. The name was changed to
Raytheon in 1925 to reflect its growing vacuum tube usiness. Did you know
the name Raytheon means "light from the gods?" In this case, the light refers
to the orange glow from the tube heater filiment. If you have ever had the
privilige of seeing in a darkened room vacuum tubes glowing inside a vintage
radio, you will understand the relationship to a godly sight. Not too many
years ago, there were still a few companies like Tesslor manufacturing new
tube radios, but now you'll have to go to eBay or similar venues to find used
radios. The prices are not too bad. ...but I digress. This 2-page advertrisement
in a 1955 issue of Radio & Television News magazine pitched a division...
 I have mentioned this before, but nearly
always the setting for John Frye's "Mac's Service Shop" technodrama stories coincide
with the time of year corresponding to the month in which it appeared (for the northern
hemisphere) - in this case the July 1952 issue of Radio & Television News
magazine. In addition to that, Barney's crack about Mac using his slide rule to
try calculating who the president would be is also time-appropriate since 1952,
being a Leap Year, was also an election year (Eisenhower beat Stevenson, BTW) ...but
I digress. Mac's actual preoccupation was with
open wire transmission lines. With the rise of UFH broadcasting on the horizon,
he predicted that such lines would become popular due to their lower signal attenuation
compared to standard 300 Ω plastic-insulated twin lead. Open line (aka ladder
line or window line) at 500 MHz exhibits about a quarter the loss when dry
and as much a twentieth the loss when wet (depending on the quality of the standard
300 Ω twin lead)...
 A few weeks ago I posted a two-part article
on the Taylor
super-modulation principle published in Radio & Television News
magazine in 1948. It was a newly announced technology at the time and was written
by its inventor, Robert Taylor. This piece entitled "Understanding Super-Modulation"
appeared a couple years later by another author, John McCord, where he describes
how it works , how to tune super-modulation circuits, and how it compares to other
modulation methods - all conveniently in "Ham language." Super-modulation is a form
of amplitude modulation (AM) that makes use of carrier and/or sideband suppression
to achieve greater efficiency. A panadaptor - aka pan-adapter, aka panadapter, aka
radio spectrum scope, aka panoramic adapter - is used to view the RF spectrum across
a wide band. Essentially it is a low budget spectrum analyzer...
 Call me a skeptic, but somehow I doubt the
accuracy of the "Radiation
Curve Representing All VHF Channels" presented in this Rear-Guard antenna ad.
It appeared in the December 1954 issue of Radio & Television News magazine.
Truth in advertising laws were probably not as strictly enforced as they are today.
The main lobe utterly dominates the response, with barely any power in the side
and back lobes. Even a well-designed, narrow-band parabolic dish is fortunate to
have such a near-perfect directional pattern. Aside from that, I wonder how many
people today "get" the picture of the kid with a pillow strapped to his behind and
understand the relationship to "Rear-Guard?" Back in the day, kids sometimes experienced
marshal punishment in the form of a hand or a wooden paddle to the body area normally
sat upon. It was known as a spanking. I know from personal experience that the threat
of receiving such punishment often served as sufficient deterrence from committing
certain naughty acts...
 According to Samuel Milbourne's "Battery
Types and Their Characteristics" article in Popular Electronics magazine,
in 1973 there were about 400 different battery types to choose from when deciding
what to buy for your automobile, electronic device, uninterruptible power supply,
flashlight, etc. I don't know what the number of types is today, but it must be
in the thousands. Nominal voltage, case size and shape, energy capacity (amp-hour
rating), current delivery capacity ("C" rating), environmental accommodation, connection
type (contact, solder, screw-on, or push-on terminals), chemistry, number of recharge
cycles (for secondary batteries), and a host of other choices are available nowadays.
Every time I need to order a new Li-Po battery pack for a model airplane or helicopter,
I spend quite a bit of time searching through mAh versus weight and physical size
specifications to identify the best - and most affordable - option. There will never
be a one-size-fits-all battery. If you are interested in vintage batteries...
 This episode of "Mac's
Radio Service Shop" is a prime example of the difference between a business
owner and an employee when it comes to always thinking about how to make things
more efficient and attractive to customers - and therefore more profitable. To be
fair, there is no reason to expect an employee to have as high a level of devotion
as an owner other than for better job security. The October 1950 story entitled
"Mending Harness," appearing in Radio & Television News magazine, is a prime
example. Mac, the proprietor, had spend many hours in the evenings completing service
jobs and clearing the shop of its sizeable backlog. Barney, the employee, loved
the situation since he thought it would mean some slack time for him. Mac, though,
planned to use that time for repairing, aligning, and improving the test equipment
- something that had gone wanting during the busy times. As always, Mac's Service
Shop docu-dramas are a good mix of useful lessons and good humor...
 Homepage
Archives for July 2023. Items on the RF Cafe homepage come and go at a pretty
fast rate. In order to facilitate fast page loading, I keep the size reasonable - under a megabyte (ebay, Amazon, NY Times, etc., are multiple
megabytes). New items are added at the top of the content area, and within a few
days they shift off the bottom. If you recall seeing something on the homepage
but now it is gone, fret not because many years I have maintained
Homepage Archives.
 This "Electronic
Crossword" appeared in the September 1958 issue of Radio & TV News magazine.
Its creator, John Gill, designed specialty theme crossword puzzles for many other
editions of Radio & TV News and Electronics World (see the big list at the bottom
of the page). He considered this crossword to be a "fooler" because he claims
to include many "unusual definitions and a number of obscure words which you will
have to work around if your vocabulary of 'exotic words' is rusty." It really doesn't
seem so difficult to me, and anyone used to working my custom RF Cafe Crosswords
will have no problem with it.
 Here are a few good soldering tips that appeared
in a 1973 issue of Popular Electronics magazine. One suggests using hot
melt glue to hold components and cables in place both for soldering and just to
keep them from moving during normal use. Another describes how to turn a standard
pistol type soldering gun into a
resistance soldering tool. It actually works pretty well for soldering sheet
brass and copper, but do keep in mind that there is a live voltage between the two
sections of wire when they are not making contact with the work piece. There's also
a recommended method of soldering stranded or braided wire like coaxial cable shielding
without having so much of the solder wick into the braid beyond where you want it
(another way is to clamp a heatsink on the braid to prevent excess wicking)...
 Carleton Phillips was not minimizing his predecessors
when he wrote this 1966 Popular Electronics article marveling at the accomplishments
in "Gay
Nineties" (1890's) in spite of their relatively crude resources. Seven decades had
passed since then. A similar article could be written today, five decades hence, about
today's knowledge and technology compared to that of the mid 1960's. For instance, DNA
had not yet been sequenced, 3D printing did not exist, Al Gore had not invented
the Internet, MRI machines were not available, there were no cellphones, PC's were only
a dream, booster rockets could not land self-powered for re-use, TV's used CRT's...
 A year after the two atom bombs were dropped
to end World War II, the newly formed Atomic Energy Commission conducted detailed
detonation tests at the Bikini Atoll, in the South Pacific. Most people more than
40 years old are very familiar with the images of the giant mushroom cloud that
formed over the site. This "Radio
in the Atom Tests" article from the July 1946 issue of Radio-Craft
magazine reports on plans being made for measure and record sound pressure, nuclear
radiation, radio and radar signatures, temperature, light spectrum and intensity,
and other parameters. The information would be used for improved bomb making, nuclear
power generation, medical imaging and treatment, and general research on nuclear
fission and fusion (a fission implosion is to initiate a fusion reaction)...
 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...
 Little did Ham radio operators know in April
of 1941 when they were enthusiastically buying equipment for their shacks that a
year later the Federal Communications Commission (FCC) would ban them from broadcasting
from their transmitters. This advertisement for a high-end Hallicrafters receiver
appeared in the April issue of Radio News magazine. Part of the feature
definition includes "calibrated bandspread
inertia controlled," and "micrometer scale tuning inertia controlled." I'm not
sure what the "inertia controlled" part is, unless it refers to how massive metal
disks were sometimes installed inside the chassis on the tuning shaft in order to
give a more solid feel to the control knob, as well as to enable the dial to be
spun and released to rapidly move through a large distance between adjustment points...
 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, and
more. Page templates are provided with a preset scale (changeable) for a good presentation
that can incorporate all provided symbols...
 Admittedly, I did not do any follow-up research
on this, but there is reason to believe that prior to this Radio News magazine
article, there was not a general agreement on what formula to use for thermal noise
in an electrical system. Here is a statement made by author S.J. Mallory, "At
first, however, there was no general agreement concerning the magnitude of this
basic Johnson noise power level. Some engineers used the quantity KTB, others used
2KTB and still others used 4KTB." We of course all use KTB nowadays for thermal
noise power - aka
Johnson noise. It's a good read on the subject of sources that determine the
noise floor of a system. There's also this kind of Johnson noise...
 Here is a short tutorial on how to construct
a
¼-wave stub "trap," or filter to attenuate even-order harmonics from transmission
lines. It applies whether the transmission line is feeding an antenna or is a section
of copper foil running on a microwave substrate. Author Kent Mitchell (W3WTO) discusses
both an open stub and a shorted stub. In case you are not familiar with how quarter-wave
transmission lines stub work, a short at the far end appears as an open circuit
where the stub connects to the main transmission line, and an open stub line appears
as a short circuit. That is because there is a 180° phase shift at the end of the
shorted stub and a 0° phase shift at the end of the open stub. Therefore, there
is a total of 360° (i.e., 90°+180°+90°=360°, equivalent to 0°) with the shorted
¼-wave stub so it has no effect where it attaches to the main transmission line.
The open stub experiences no phase shift...
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, and
more. Page templates are provided with a preset scale (changeable) for a good presentation
that can incorporate all provided symbols... |
