1996 - 2016
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 ...
All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.
My Hobby Website:
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:
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 ...
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 ...
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 ...
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 ...
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 ..."
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 ...
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.
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...
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...