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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Hybrid Tube Amp for the Raspberry
Pi
 Vacuum tube products, once the domain of vintage equipment collectors
and restorers (like moi), are increasingly becoming part of the mainstream
retro electronics movement. Usually the tube portion of a circuit is limited to the output amplifier
or maybe a preamplifier in an audio frequency application, where amplitude stability is not a major
performance factor. RF tuning and detector circuits use, thankfully, modern microelectronic components
in order to benefit from precision digital tuning and even computer interfaces. Audiophiles have long
held that the microphonic action of physical elements within the
vacuum tube adds a warm quality to sound that cannot
be replicated with solid state devices ...
5/12/2016
NFC & Holographic Business Cards
 For not an awful lot of money (about $1.50
each) you can buy business cards that have an NFC antenna and chip built in that will transfer
your selected information to an associate's cellphone or tablet computer. Bump your card on someone's
phone and have it connect to your LinkedIn or Facebook page, go to your website and/or have a bookmark
added, open an e-mail with your address already typed in, have a digital version of your business card
appear, download an app, or open a video chat. Each company has its own variety of functions available.
A nice feature of the NFC business card is that you
can update it online with new information and functionality to reflect contact changes or just about
anything that comes as part of the original design package. Many manufacturers provide the capability
to monitor ...
4/8/2016
Withwave Coaxial-to-Planar T-Probe™
 Mr. Richard Song, a very friendly fellow I knew when he worked
for a different company, wrote to me recently saying he was now the Marketing Director for South Korean
RF and microwave product company Withwave, Inc.
Withwave's offerings are similar to what he had been
 working on, so the move was a natural transition. While perusing Withwave's
product line is primarily coaxial connectors, cable assemblies, and accessories for test applications.
One item in particular really interested me: the coaxial-to-planar
T-Probe™. Per Withwave's
website: "Withwave's T-Probe is coaxial probe that offers one signal pin on center and several fixed
pitch ground contact with low inductance. This probe provides excellent electrical performance
..."
12/1/2015
Why Be Würth-less When You Don't Have to Be?
 A
couple weeks ago, Ms. Heather McGhee, of Wurth
Electronics Midcom, wrote to me asking about getting a listing on Vendor pages for which her company
manufactured products. I obliged accordingly by adding Wurth Electronics to the Automotive Electronics,
Capacitors, EMC / EMI / RFI, Hardware, Inductors, and Substrates / PCBs pages. Wurth Electronics Midcom,
if you are not familiar with the company, is part of the Germany-based Würth Elektronik Group companies.
Combined, they produce thousands of circuit board-based system components for power distribution, display
and control panels, electronic controls. Power magnetics, EMC components, common mode chokes, capacitors,
transformers, RF inductors, high current PCB terminals, printed
...
The 'Kit' Has Finally Been Put Back in Heathkit™ !
 I signed up as
a 'Heath Insider' about a year ago when
news first broke about Heathkit's intention to finally, after a couple decade hiatus, begin producing
built-it-yourself electronics kits again. The
Explorer Jr.™ is a basic capacitor-tuned AM radio kit that comes complete
with everything needed to build it. Why not a digitally tuned synthesizer with an LCD display? Company
president Andy Cromarty promises many more kits to follow, with all being in the classic Heathkit tradition
of high quality parts and well-written, illustrated, step-by-step instructions. It will be a continuation
of their "You Can Build It. We won't let you fail." motto. An e-mail arrived a few days ago stating
the following: "Here's a quick summary of what we've quietly been doing at Heathkit during the past
year: We assembled a terrific team of very talented
...
10/18/2015
Datamancer Enterprises
 The December 2012 edition of IEEE's
Spectrum magazine had this setup from Datamancer Enterprises. BTW, the suffix 'mancer' means prophet or fortune teller.
From their website: The Clacker is a full PC suite including keyboard, mouse (made from a telegraph
key), mouse pad (ancient map image), PC, LCD, speakers (vintage Atwater-Kent speakers which have been
modernized), and a classic table and matching chair. The PC features a powered, spinning brass mechanical
display reminiscent of Charles Babbage's 'Analytical Engine' and 'Difference Engine', which were giant
brass mechanical calculators invented in the early 1900s whose functions influenced the design of modern
computers. The Clacker ships with a 'Marquis' keyboard. The LCD also features an antique video
projector built into the back which is powered and spins custom brass film reels while LED lighting
flickers in a custom projection box, to give the impression that the image is being projected onto the
LCD through the back. Spectrum says the price is $15k-25k. If you buy yourself one, please
have a second sent to me. Thank-you in advance. 1/7/2013
MapleSoft
 A website visitor wrote recently
and mentioned that he qualified for a "Personal" edition of the highly capable
Maple mathematics software
by MapleSoft. He got v15 a while ago for just $260 (up to v16 now). The
standard price is north of $2k, so $260 is a heck of a deal. My version of MathCAD is about 15 years
old and won't run on Win 7, so I figured it would be worth asking if I qualify. My application
would be to create equations and graphs for posting on RF Cafe. Maple's abilities are far beyond my
simple needs with its ability to solve complex equations, produce sophisticated visualizations
(aka charts), produce professional reports, and more. Many built-in engineering
and science functions are available. The symbolic math engine makes laying out system diagrams and equations
simple and intuitive. A student version can be had for a considerable discount
(couldn't find a price on their website). There are Maple packages available
on eBay, but they are probably not legitimate and therefore cheat MapleSoft out of deserved profit.
BTW, I do not qualify for the Personal user price, and since my application would be to provide stuff
to people for free, it's not worth the cost. Looks like MathCAD 3.1 will have to do me for a while longer.
5/9/2012 GemTune GS-02 KT88 Vacuum Tube Audio Amplifier
 Audiophiles
rejoice: What's old is new again! If you have been longing for the fabled tones that, according to the Apollonic
faithful, only a vacuum tube amplifier can produce, then the
GemTune GS-02 might be what
you have been looking for. Of course you could buy a vintage tube amp off of eBay or at a Hamfest, but
maybe you don't have time or knowledge or desire to recondition it. One nice feature of the GemTune
GS-02 is that the five vacuum tubes it uses, one (1) each 5Z3PA and two (2) each KT88 (matched pair)
and 12AX7, are readily available, whereas you could have trouble...
6/4/2013
Vasari Ecotect
 While on a software
theme for the Cool product (Maple math software featured last week), I ran across a demo for wind analysis
software that architects and civil engineers for predicting building structural loads, wind velocity
at street level (recall stories of gale-force winds generated between tall buildings due to venturi
effect), land erosion, and more. Both 2-D and 3-D simulations are possible. Vasari Ecotect Wind Tunnel
color-coded graphs look a lot like many of the finite element analysis (FEA) and computational fluid
dynamics (CFD), vector field plots that we are accustomed to seeing for electric and magnetic field
analysis, thermal maps, and load stress analysis on mechanical structures. It is no coincidence since
many of the equations and techniques are either exactly the same or very closely related. Recall in
physics and circuit analysis classes how often mechanical analogies were used for explaining electrical
principles, and vice versa. This is actually part of Autodesk's Project Vasari which was created specifically
to analyze conceptual building layouts. Remcom's Wireless InSite looks a lot like the Wind Tunnel software
in that it models fields surrounding and even through buildings in an urban environment. The difference
is that Wireless InSite projects EM fields rather than wind fields. Anyone in the wireless network planning
business might want to look into this software since it appears to include multipath effects on signal
integrity...5/16/2012 Wireless InSite
 A dozen times or so each year I get requests from people looking
for point-to-point (PtP, P2P)propagation software that is sophisticated
enough to take into account dense urban environments, terrain reflections, weather phenomena, etc. The
first thing I recommend is checking into AlphiMAX's free PtP Estimator online application. Someone
pointed out that while PtP Estimator is a nice free program, it requires uploading your system
information to the company's website, and that he was not able to reveal his system's venue and frequency
/ power specifications. If that is a problem for you, Remcom, a well-known electromagnetics simulator
company, has a product called Wireless
InSite® that is purchased and run on your own computer. "Wireless InSite is a suite of ray-tracing
models and high-fidelity EM solvers for the analysis of site-specific radio propagation and wireless
communication systems available through a common user interface. The software provides efficient and
accurate predictions of propagation and communication channel characteristics in complex urban, indoor,
rural and mixed path environments. Applications range from military defense to commercial communications,
wireless communication links (link budgets), antenna orientation and coverage, including interference
from multiple transmitters."5/23/2012 Tesslor Model R601S Tube AM/FM Radio
 In 1983, my wife, Melanie, gave me a 1941 vintage floor model
Crosley
radio that my sister, Gayle, found in a barn on the Eastern Shore of Maryland. It was in pretty
rough shape; after totally restoring and painting the metal parts and stripping down and refinishing
the wooden parts, it looked pretty darn good (see picture). Unfortunately, I do not have any pictures
of April 23, 2014 - My Tesslor R-601S is back back from the factory with an upgrade that add Bluetooth
3.0 capability and an improved sound board. See my review of the
Bluetooth-enabled Tesslor R-601S with a new video. the electronics. Amazingly, in
1983 the local Radio Shack still had a vacuum tube tester in the store, so I was able to identify and
replace the weak ones. I got rid of the old paper capacitors, gave everything a good look-over... 4/11/2012
Radio Mobile
 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, 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.
Elevation data for most of the world is available, not just for the U.S. and Canada. A very nice feature
of Radio Mobile is the ability to predict performance between a fixed station and a mobile station
in motion. Frequencies for 20 MHz to 20 GHz can be explored for transmitter powers ranging
from 10 nW up to 1 MW. Antenna gain of -10 to 100 dBi is available, with line losses
up to 500 dB. Receiver threshold of 0.01 to 2,000 μV is accommodated. You can specify environmental
parameters like climate (equatorial, continental, marine, etc.), modes of variation (spot, accidental,
mobile, broadcast), ground conditions (conductivity, relative permittivity), and statistical variations
(time, location, situation). Interestingly, a search... 6/13/2012
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