Featured Product Archive
The inventions and products featured on these pages were chosen either for their
uniqueness in the RF engineering realm, or are simply awesome (or ridiculous) enough
to warrant an appearance.
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 Occasionally an unbuilt vintage Heathkit
item appears on eBay with really nice photos of the contents. In fact, I have
a Saved Search that sends me an e-mail whenever one shows up. This morning,
a
Heathkit DG−140 Two-Station Intercom kit appeared on auction. The instruction booklet has a
publish date of 1972, so I looked for a copy of it on the WWW but the only thing
I could find was a PDF for purchase. Despite the 1972 date, it appears it was
1973 when the DG−140 was first available. The 1971 catalog still shows the previous
version, the DG−141 (which you might understandably think would be the newer
model number). There is a big difference in the chassis configuration from the
DG−141 to the DG−140. Per the 1973 Heathkit catalog, the DG−140 was priced at
$29.95 ($184.91 in 2021 money - a whopping 6.2x factor in 48 years). Heathkit
products were well known for the completeness of its instruction manuals, with
clearly illustrated instructions...
 It's not quite as monumental a find as
discovering the Dead Sea Scrolls in a cave, or an original showroom-new Ford
Model T sitting in a barn, but what Martin H. came upon in the attic
of a old house in Gorlitz, Germany, definitely rates an "amazing!" response.
Sitting on the Polish border, previously owned by an east German policeman,
the domicile contained one each of the following pieces of vintage Rhode &
Schwarz test equipment in brand new condition: • R&S Resonance
Frequency Meter, Type WAM, BN 4312/2 (ca 1968) • R&S Phase
Meter, Type PZN, BN 1941 (ca 1965) • R&S Power Signal Generator,
Type SMLM, BM 4105 (ca 1974). Martin is looking for a buyer for all
three of these magnificently preserved pieces of electronics history. The photos
show no sign of damage, contamination or fading...
 For the past few months, this full-page
BridgeCom advertisement has been running in the American Radio Relay League
(ARRL) magazine QST. When I first saw it I though it might be one of
those research laboratory hydraulic apparatuses for generating the kind of pressure
found at the center of the Earth. Scientists use such devices to synthesize
diamonds by compacting coal. In actuality, the four cylinders are part of the
BridgeCom BCD-144250
Rack Mount VHF Duplexer. Per their website: BridgeCom Systems' BCD-144250
Duplexer for amateur and commercial applications. The BCD-144250 utilizes four
high-quality cavities that results in uncompromising duplex isolation. It will
handle up to 250W continuously for the most demanding applications...
 It has been a long time since I've had
a
citizens band (CB) radio in my car. Back in the 1970s when the CB craze
was at its peak, with songs like C.W. McCall's "Convoy"* topping Casey Kasem's
American Top 40 (AT40) charts, my high school compadres were all installing
23-channel CBs (standard at the time) in their cars and pickups. I joined in
with a Radio Shack unit (don't recall the model number). In those days the FCC
required operators to register and mail a check for a few bucks - same with
radio control (R/C) systems for model airplanes also operating in the same 26-27 MHz
radio band - in return for a "Citizens Radio Station License" document to carry
in your wallet. Most CB channels were spaced at 10 kHz, but the R/C frequencies
were in−between some CB channels spaced at 20 kHz. For instance, my 3-channel
OS Digitron R/C system was at 27.195 MHz, which resided between CB channels
19 (27.185 MHz) and 20 (27.205 MHz). Some electronically savvy CBers
would illegally modify their radios to include operation on those in−between
frequencies (e.g. Ch 19A at 27.195 MHz), thereby creating a scenario where
merely keying up the transmitter could "shoot down" a model airplane if close
enough...
 Dr. Scott Best, of SiberSci
RF engineering services, sent information about the FREE general purpose
DISLIN scientific and engineering
plotting software library that includes Smith Chart support. The graphics
library was initially created at the Max Planck Institute for Solar System Research
beginning in 1985 by Mr. Helmut Michels. Its continual series of upgrades
is as recent as May 2020. The DISLIN library is available for Unix, Linux, FreeBSD,
Windows, Mac OSX, and MS-DOS systems. It supports a variety of public domain
and commercial compilers for Go, Perl, Python, Java, Ruby, TCL, Julia, FreeBASIC,
Free Pascal, R, C/C++, and Fortran (77, 90, and 95). If you are a software developer,
you probably know that most development platforms are supplied with either no
plotting components or very rudimentary versions of for-purchase products. Many
cost hundreds or even thousands of dollars...
 NI (National Instruments) has made their
LabVIEW Student Edition software product available as a free download for students
needing it for school projects. The license is good for 6 months. You can always
download a trial of standard LabVIEW, but it only has a 30-day license. The
LabVIEW Student edition includes most of the same features as the full LabVIEW
suite but adds a watermark on the front panel and block diagram. The download
screen requires some personal information if you do not already have a NI account
set up, but that is not unusual or unreasonable when a company is offering you
trials software. I did the download and was going to set it up and get some
screen shots, but after 15 minutes or so it was still installing (and that's
on a solid state hard drive, SSHD), so I killed the process and figured I'd
find a video that someone else had done. If I had a use for the program I would
have let it go ahead and complete the installation, but otherwise I didn't want
that much new stuff on my SSHD. Even though it is called Student Edition, there
is no requirement that you prove that you are a student....
 As this is written, we in the U.S.
are nearing the end (hopefully) of the virtual house arrest period most of the
country has had imposed upon us by overzealous politicians. Part of the "comeback"
plan being bandied about by governors is requiring subjects/citizens to don
cloth face masks
when in public places where the arbitrarily conjured up six-foot "social distancing"
rule cannot be easily maintained. There is no foreseeable end to this "new normal"
imposed upon most of the world. Contrary to what many people believe, the mask's
purpose is not to prevent the wearer from inhaling COVID-19 (aka Wuhan Virus,
China Virus - pick your favorite) particles, but to arrest the body fluids emanating
from the wearer's mouth and nose from being spewed into the air and/or onto
surfaces. In response to the shortage of N95 type masks that are supposed to
stop up to 95% of virus particles, many private citizens - mostly women - worked
with health care personnel to design cloth masks that are comfortable to wear
for long periods of time and are reusable by washing them...
 Phil Salas, AD5X, published an extensive
review of the NanoVNA
vector network analyzer in the May 2020 issue of the ARRL's QST
magazine. Unfortunately, the article is not available to non-members, but if
you are a member or know someone who is, it would be worth reading. He compared
measurements by the NanoVNA with those obtained using an Array Solutions VNAuhf,
which yielded very favorable results. There are many knock-offs of the NanoVNA
available, which is typical since most of these low-cost, high-performance electronics
devices are built using widely available block-level components that make replication
relatively easy. Variations in the quality of coaxial connectors, internal batteries,
switches, etc., can and often does make a big difference in the quality and
ruggedness of the equipment you buy. Firmware and support software can vary
significantly as well. It's a roll of the dice to some extent...
 Randy Rogers*, AD7ZU, mentioned in the
May 2020 issue of QST magazine the Smith Chart software called "SimSmith," by Ward
Harriman, AE6TY. SimSmith first appeared around 2011. Being written in Java,
it will run on any operating system that supports Java (Win64, Win32, Apple
Mac OS X, Solaris, and Linux). If you are using Win64 as I am, you will want
to download the "windows64-with-JRE.exe" file. Windows security will try to
block it, but it is safe to run after your antivirus program scans it and gives
a green light. AE6TY recommends using the installation files rather than just
downloading the "SimSmith.jar" file even if you already have a version of Java
installed. When launching the program, the window might not be very large, so
grab a corner and stretch it out so the components are easier to see. After
playing around with SimSmith for a while, you might want to click on the "SimSmith->preferences"
menu selection...
 RF Cafe visitor Mike M. reminded
me of "Madman Muntz," who was
a widely known television commercial personality on the West Coast from the
1950s through the 1970s. Earl William "Madman" Muntz's zany live and animated
commercials were used highly successfully in selling cars, including one he
himself designed and manufactured called the Muntz Jet. Along with being a master
salesman, Madman Muntz was also a self-taught electronics engineer of sorts.
He is credited with developing the first 4-track stereo tape deck for cars,
which was a precursor to the 8-track tape deck. What Mike mentioned specifically
was the line of Muntz television sets. Not satisfied to merely manufacture TV
sets, Muntz created an entire service shop and fleet of mobile television trucks.
It was kind of an early version of the Nerd Herd. Based on the Madman's trademark
method of minimizing the number of components used in his products...
 Dr. Michael Steer, Lampe Distinguished
Professor of Electrical and computer Engineering at the NC State University,
has released half a dozen of his books on RF system and circuit design in the
form of OpenAccess eBooks, and are downloadable at no cost on the NC State
website. Dr. Steer is a prolific author whose books are chock full of highly
useful illustrations and photographs. The first five "Microwave
and RF Design" books, volumes 1 through 5, cover a wide swath of ground
with concentrations in radio systems, transmission lines, networks, modules,
and amplifiers and oscillators. The final book, "Fundamentals of Microwave and
RF Design," is a summary of the first five that will prove useful to newcomers
in the field. Excerpts of the books' contents are quoted ...
 Fellow amateur radio enthusiast Russ
Keller (KM4RHK), of Wake Forest, North Carolina, has designed and is selling
his DMMCheck Plus test device
for verifying the accuracy of digital multimeters, oscilloscopes, or other instruments
which measure the provided parameters. This compact (2.5" x 2.2"), inexpensive
board is battery powered and can be used to verify the accuracy of seven primary
DMM functions. A very complete description of each function is provided on the
DMMCheck Plus website. A certificate of measured values for each function
is provided with the DMMCheck Plus. Re-measurement, if desired, is free
for the first two years ...
 While company branding and the user interface
have changed over the years since AppCAD first
appeared on the Hewlett Packard (HP) website, it is still as handy a desktop
tool as ever. The most recent incarnation was provided by Avago Technologies,
which bought Broadcom in 2015 and then adopted its name. You can now download
a free copy of AppCAD from the Broadcom website. Rather than do en extensive
write-up about all the calculation screens in AppCAD, I've posted a sampling
of screen shots. Amongst them are a Smith chart s-parameter plotter, a lumped
element balun designer, a microstrip calculator, a mixer spurious product calculator,
and thermal dissipation calculator. Since according to a popular saying a picture
reportedly paints a thousand words ...
 Those of us whose were around in the RF
industry in the 1990s and remember a very fine magazine entitled "Applied Microwave &
Wireless." It was published by Noble Publishing Group. The Archive.org
(aka the Wayback Machine, a la from Sherman and Mr. Peabody cartoon)
website has an archive of 410 published articles (as of this writing) on a variety
of topics including antennas, oscillators, filter design and tuning, direct
conversion receivers, microstrip and stripline, RF link calculations, shielding,
co-channel interference, power amplifiers, lightning protection, SAW devices,
GPS, dielectric measurement, circuit and system computer simulation, transistor
biasing, RF transformers ...
 If you visited the good folks at the
QuinStar Technology booth at the
IMS show in Boston this year (2019), you were probably offered one of the T-shirts
shown here. As you might expect from a company of engineers and scientists,
the design on the T-shirt includes a thinking exercise. Rumor has it that this
is the first question put to interviewees. Can you decode the license plate
message? I asked Ms. Carol Clasby, who probably handed you your T-shirt
at IMS2019 (if you got one), whether someone at QuinStar actually has the license
plate and she responded not yet, but maybe in the near future. I went to the
California Department of Transportation website to see what such a license plate
might look like. It allowed me to reserve the plate, although of course ...
 It seems impossible that you can buy
Visio Professional 2019 and Microsoft Office Professional Plus 2019 for
less than $10 each, but according to the research I did the offers seems to
be legitimate. Evidently, sellers buy corporate subscriptions and then are licensed
to distribute copies to it agents (we, the buyers). This is nothing new because
I have seen it done for many years. After purchasing a product, you are provided
with a hyperlink for downloading the software directly from the Microsoft.com
website, and also an activation key. Heeding te old saying about if something
seems too good to be true, it probably isn't, I decided to test the system.
Back in March, I purchased one copy each of Visio Professional 2019 and Microsoft
Office Professional Plus 2019 for $5.99 and $9.99 ...
 My daughter, Sally, in addition to owning
and operating a very successful horse riding school named Equine Kingdom Riding
Academy, has a rather large eBay store she uses as a venue for selling items
purchased at the local Goodwill "Bins" store. She often buys vintage toys with
electronics features - sometimes working and sometimes not. A properly functioning
vintage toy, be it a stuffed animal or a game of some sort, can make a huge
difference in the resale price. When that is the case, she sends them home with
me to attempt a repair. Many times the problem is corroded contacts from leaky
batteries. A dental pick and some isopropyl alcohol usually solves the problem.
When that doesn't work, it's time to open 'er up for a deeper look. Over the
years I have found problems ranging ...
 There's a new online interactive Smith
chart s-parameter plotter in town, and it goes by the name of
QuickSmith. Justin Coulston, designer of QuickSmith, sent
me an e-mail asking that I take a look at it. I did, and I like what he has
done. Assuming that anybody reading this is already at least somewhat familiar
with the Smith chart, this report will concentrate on the features of QuickSmith.
Keep in mind while checking out QuickSmith for yourself that it is still in
Beta phase, so your feedback to Justin will be appreciated ...
Coilcraft has been around
as long as I can recall since beginning my electronics career in the 1970s.
In fact, Coilcraft was founded in 1945 near Chicago to make custom coils for
television sets. They began manufacturing a line of standard products in the
1970s - no doubt with supporting my budding career in mind ;-) Inductors
and magnetics are their primary focus. Coilcraft has been an industry leader
in surface mount components, and was one of the first to provide packaging that
could be used by pick-and-place automatic PCB assembly ...
 A couple days ago I posted an update
on the Watkins-Johnson databook page that had an unauthorized gag graph titled,
"WJ-G1/SMG1 Phase vs. VCTL vs. Frequency vs. Phase of the Moon." When RF Cafe
visitor and sometimes contributor Dr. Marek Klemes* read that, he sent me a note about
remembering this "Delayed
Light Turn-Off" circuit from the Signetics 555/556 Timer Databook. It took
a bit of creative Googling, but he managed to find the datasheet (to the right).
The text was a bit washed out from the original low resolution scan, so I reproduced
the labels (green). This Rube Goldberg-ish contraption works thusly: After a
delay determined by the values selected for R1 and C1,
the output of the NE555 timer goes high and causes resistor RL to
heat up enough to ignite match M1. M1 subsequently lights
the fuse on firecracker FC1, which has tied to its body a string
that wraps around a pulley and holds a rock (which weighs precisely 2π pounds ...
12/7/2018
Longtime RF Cafe visitor, electrical engineer, and occasional contributor
Alan Dewey sent me a note yesterday saying a book for which he helped provide
a large amount of research data has been published by authors Iain Dey and Douglas
Buck. "The
Cryotron Files: How the Inventor of the Microchip Put Himself in the KGB's Sights,"
is an extensive delve into the background of Dr. Dudley Allen Buck, whose
son, Douglas, conducted an extensive investigation into his father's mysterious
death that happened to coincide with the death of his colleague and two other
scientists just days after being visited by Soviet computer experts. Dr. Buck
was a superconductivity researcher during his short, highly productive life.
A cryotron, BTW, is a superconducting switch that would make for very low power
supercomputers if it could be made practical in IC form ...
11/20/2018
 An advertisement for Mini-Circuits' DIY
Vector
Network Analyzer Kit appeared in the October issue of Microwaves & RF
magazine. It is evidently the first of a planned series of University Projects.
Billed as an attempt to "Bridge the gap between textbook theory and real-world
measurement," Project No. 1-UVNA-63 targets college laboratories as low-cost
means of procuring a high performance vector network analyzer (VNA) at a reasonable
cost ($2,495.00). The frequency range is 100 MHz to 6 GHz. Having
the student build the 1-UVNA-63 provides a familiarity with a block diagram
level understanding of 2-port VNAs and gives hands-on experience with assembling
RF components. Included are filters, directional couplers, a transceiver PCB
(made by Vayyar) ...
11/1/2018
 Take a look at this
ARRA (Antenna & Radome Research Associates)
attenuator advertisement that appeared in the September 2018 issue of Microwaves & RF
magazine a tell me if it reminds you of something you might have seen in the
1960's through 1980's. That might not have been the intention, but seeing it
sure triggered my nostalgia mechanism. Even the tag line, "When it comes to
attenuators, nobody - but nobody - can fill our shoes," idiom, being somewhat
dated, conjures up memories of vintage company slogans. Of course the black
and white format feeds the perception. Maybe I'm wrong, but if it appeals to
me for any reason, the ad designers have done their job ...
10/9/2018
 Rohde & Schwarz has been publishing
a series of good old-fashioned printed (aka hard copy) Pocket Guides on RF test
and measurement topics. This latest one titled, "Key Characteristics of Signal Generators and Modulation Methods:
Pocket Guide," arrived in my mailbox (the physical one at the curb, not
Outlook). There are 116 pages chock full of an amazing amount of descriptions,
equations, tables, and graphs. The main topic areas are analog, vector, and
arbitrary (ARB) waveform generators, and analog and digital modulation methods.
It also reviews associated topics like phase noise, VSWR, intercept points,
etc. A sampling of them are reproduced below. You can get your own free copy
by filling out the form on the R&S website ...
10/8/2018
 Sitting in the waiting room in the local
Jeep dealership, waiting for the technicians to do the annual inspection on
the 2011 Patriot, I noticed a 12 volt car battery sitting on a table. At first
I assumed it was just a sales pitch for a new battery, but then I noticed a
bunch of small cables coming from its bottom edge. As you can see in the photo
I took of it, those cables are mobile device charging cords with mating connectors
for Apple, USB, and miniUSB ports. An Internet search did not turn up any of
these things, so maybe Mopar engineers came up with it. Times sure have changed
from when ...
6/18/2018
 Rohde & Schwarz is offering at no
cost a variety of reference charts (posters) for hanging on your lab or office
wall, and some handy-dandy
Pocket
Guides. In the current age of (seemingly) paperless offices and laboratories,
opening a cardboard package from R&S containing the pictured items caused
me to wax nostalgic over the days when sales reps handed out such materials
during workplace meetings and at trade shows. Wall charts are still fairly easily
obtained, but the spiral-bound pocket guides are more rare. Maybe soon we'll
be seeing the resurrection of cardboard slide rule calculators ...
3/14/2018
 Mr. Oleg Sakharov, Director of the Center
of Telecom. Technologies, LLC, recently sent me information on the
MLinkPlanner software for performing microwave communications
link design. Judging only from the provided screenshots and the online documentation,
MLinkPlanner looks to be very user friendly and loaded with features. I downloaded
the 7-day free trial and did a quick fictitious link between my house in Erie,
PA, and the WBEN AM radio station in Buffalo, NY. My route is mostly over Lake
Erie, so there was not much in the way of obstructions, other than the curvature
of the earth ...
12/18/2017
 Hyperlinks all around the Internet pointing
to Hittite's infamous Mixer Spurious Product Calculator broke suddenly when
Analog Devices swallowed up Hittite in 2014. The good news is that if you still
want to use it, you can find it as the ADI Mixer-Spur Graphical Representation
tool on the ADI website. However, Marki Microwave now has a much nicer
Spur Calculator that you will want to consider. It provides
both a Spur Web format and a Spectrum Analyzer format for presenting mixer spurious
products. The interface is very user friendly both for the input and the output
specification. The Spur Web screen uses a format pioneered ...
12/1/2017
 QuickSmith, a creation of Nathan Iyer,
has been around for a long time. It is without a doubt one of the most feature-filled
examples of RF design software around. Nathan recently released a Web-based
version of QuickSmith on a GitHub server, which means it works on any platform
with a browser - desktop or mobile. Access is free, and you can save and reload
your design files rather than losing your work once you leave the website. Being
online also means that the latest version is always available. The screenshot
to the right illustrates where to place series and parallel components, and
where to access the sweep ...
8/30/2017
 You might think the world doesn't need
another RF basics book, but the fact is there are so many new people coming
into the field that there is always room for one more - particular a well-done
edition like "RF Basics Handbook" from Rigol Technologies. The PDF download
is free, but you do need to fill out a submission form. A replication of the
table of contents give you an idea of all the topics covered. The photos and
drawings are very good quality. Of course the equipment used in the publication
are representative of Rigol's product line, but that's to be expected ...
8/15/2017
 Amateur radio operators take note: Heathkit,
which in years past was a prime supplier of homebuilt ham radio gear, has just
announced plans to manufacture its first piece of test equipment in three decades.
"Now there's the Heathkit® HM-1002: Intuitive, intelligent, affordable, accurate
measurement. The next-generation
Heathkit® HM-1002 Precision RF Meter™ picks up where our venerable
SWR / wattmeters of yesteryear -- and everyone else's -- stopped. Incredible
new features, yet simple for beginners to assemble and understand. And you can
build and maintain it yourself." ...
6/26/2017
 Dr. Andrei Muller, progenitor of
the world's first 3D Smith
Chart software program, has teamed with a handful of able colleagues to
release this commercial version of this paradigm-changing design and analysis
tool. 3D Smith Chart enables you to visualize S-parameter data in ways
not possible from the Flatland dweller's perspective that is the traditional
2D Smith chart. Flatland existed in a plane, and from an observer's perspective
a 3-dimensional object entering the plane from along the Z-axis seemed to appear
out of nowhere ...
5/22/2017
 This back-page advertisement by
Model Rectifier Corporation (aka MRC) appeared
in the January 1972 issue of American Aircraft Modeler magazine. Note
the cool collection of [now] vintage test equipment
shown in support of testing the R/C system. The advertisement shows a rhombic
antenna, the Dana 8015 RF frequency counter, Tektronix 7904 oscilloscope, HP
spectrum analyzer, RF communications synthesizer RF generator, Anritsu precision
field strength meter. I was 13 years old at the time, and anxiously watched
for in the mailbox each month ...
4/17/2017
 RF Cafe visitor Tony C., who is an
engineer working for on of America's great, longtime manufacturers of green
farm equipment, sent me a link to this unique memory IC released by Signetics
on April 1, 1973. Being April 1, 2017, it seems to be an appropriate day to
post the Signetics 25120 Fully Encoded, 9046 x N, Random access Write-Only Memory
datasheet that per Wikipedia, "...was created 'as a lark' by Signetics engineer
John G 'Jack' Curtis and was inspired by a fictitious and humorous vacuum tube
datasheet from ..."
April 1, 2017
 How many times have you dug through a
drawer of coaxial connector adapters and
found what seemed like every possible combination of TNCs, Ns, SMAs, TNCs, UHFs,
SMBs, and <fill in the blank>s except the
one you really need? Sometimes the reason is simply because all on hand are
being used for something else and cannot be 'borrowed' for your use. Other times
it is because the need never existed before. Usually, a quick search on the
Internet will turn up exactly want you want, but for decent a quality adapter
you will pay a stiff price - especially if it is a rare combination of connector
types. The truth is, not often is a combination like QMA-Male-Right-Angle-to-TNC-Female-Bulkhead
adapter or
...
7/15/2016
 Just
as the paperless office, predicted to quickly become a reality when personal
computers were beginning to dominate the workplace and home in the 1980s, has
yet to occur, neither has desktop software for high-end applications totally
replaced online equivalents. Microsoft has made good progress in the last few
years in moving part of their Office suite online, you still need a local copy
of Visio, Project, and even their Visual Studio software development tools if
you want to use them. Graphics and video editing software cannot be used efficiently
online. The problem is mostly due to time latency between user input and software
display response. Speed on the host server end is addressable with pumped up
computing power and extra
...
7/7/2016
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