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What's in a number (3253)?

The FST3253 dual four-to-one mux/demux IC has long been used as a "Tayloe Detector" or QSD (and QSE) in low-cost SDRs.    They provide incredible performance for such a simple circuit, converting RF to baseband IQ with low loss and the ultimate in simplicity. Unfortunately the original FST3253 part has become obsolete and while substitutes are available, this is where t...  READ MORE
ranickels
02/06/2024
Technical
Hot to simulate vacuum tubes in LTSpice

LTSice is a powerful simulation tool that is provided free by Linear Technology Corp.    It comes with a complete library of passive and common analog solid-state components but if you want to use it to simulate vacuum tubes, it doesen't work as-is.    Even though triode and pentode symbols can be found in the "Misc" folder, they are just schematic symbols a...  READ MORE
ranickels
09/24/2023
Technical
DIY DEG - Homemade Droplet Energy Generator works!

I'm not ready to publish a description of exactly HOW it works, but 20 minutes effort with scissors and tape produced a prototype  Droplet Energy Generator that allows me to say for sure that IT WORKS! I duplicated the design shown in this video.    I wrapped a scrap of plastic in aluminum foil, then applied a strip of double-sided tape and to that attached a piece of PT...  READ MORE
ranickels
03/30/2022
Technical
Ceramic Loading Capacitor Replacement

Old style mica capacitors were used in the pi-net matching sections of several vintage transmitters and the combination of age, heat, and high RF currents have made them likely failure items.    My Collins 32V-2 transmitter was to the point where it would not properly load to full power on 75 meters so something had to be done.   Mica capacitors are no longer made but fortunately n...  READ MORE
ranickels
03/19/2022
Technical
Universal Frequency Converter

I found myself wanting to convert various frequencies to other frequencies and wanted a cheap and easy solution, so I designed a simple "universal converter" using the NE-602 and a programmable oscillator from Epson.   I'd used the same combination in hundreds of "RANVerter" SDR Upconverter projects since my Dec. 2013 QST article and knew that while there were limitat...  READ MORE
ranickels
03/17/2022
Technical
Magnetic PCB holder

It's always a challenge to hold PC boards during assemly and testing.   After purchasing a magnetic holder from Amazon  I realized I wanted more and could easily make as many as I wanted using inexpensive 3 mm hardware from eBay and some strong "fridge magnets".     All that's needed is to epoxy a standoff to the magnet - both tapped and threaded&nb...  READ MORE
ranickels
03/09/2022
Technical
Si5351 Quadrature Mode

The Si5351 has been the biggest boon to homebrewers since the invention of the NE-602, especially now that quartz crystals are essentially obsolete.    But it's redundant to run the output of the 5351 through a johnson counter to develop the quadrature signals required for QSD/QSE SDR front-ends when there are three clock outputs available and the IC allows for phase offsets. &...  READ MORE
ranickels
03/09/2022
Technical
Some tips on the Johnson Pacemaker

It's pretty well accepted that the Pacemaker was not EF Johnson's finest effort.    In fact it was the first of several failed attempts by the King of the AM Transmitters to make the transition to SSB.    In the end, it was the rise of CB popularity that kept the company viable, along with its component business, while their ham business gradually faced away. ...  READ MORE
ranickels
03/03/2022
Technical
Radio Belts

Some things you can improvise around, others - no way!   And drive belts for radios are one of the latter, when one is broken or stretched to be unusable you need a new belt - but where to get it?   Here's the answer:   RADIO BELTS Many standard belts are shown but custom belts are no problem, just send them the information needed.    A gr...  READ MORE
ranickels
02/14/2022
Technical
The 8122 Story

The following information is attributed to Jim Liles, K9AXN.   Jim a long time user and expert on the Hallicrafters SR-2000 "Hurricane" with involvement going back to it's original production.   His website www.k9axn.com contains a lot of valuable information and is recommended.   RCA developed the 8122 which was also built by Burle, and later, Eimac ...  READ MORE
ranickels
01/22/2022
Technical
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