RF Cafe Software
About RF Cafe
1996 - 2022
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
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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.
All Featured Product Archive Pages:
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 ...
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 ...
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 ..."
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 ...
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.
MapleSoftA 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.
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...
Vasari EcotectWhile 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...
Wireless InSiteA 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."
Tesslor Model R601S Tube AM/FM Radio
In 1983, my wife, Melanie, gave me a 1941 vintage floor model
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...
Thanks to a tip by RF Cafe visitor and contributor
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...