From the Twittersphere

The Twittersphere is kind of like the ionosphere. It helps you make contact with other hams and brings you news from far and wide. Here are a few interesting links that I found on Twitter in the last day or so:

Global Pirate HF Weekend 14-15.1.2012.  This station lists pirate SW radio stations that it expects to be on the air this weekend. They include one using the callsign WEMP. Look for it between 15.005 – 15.095 MHz. They’ll be broadcasting with 100 W to Europe: 12.00 – 16.00 UTC – (check 15.010 or 15.040 or 15.090 MHz).

The Evil Mad Scientist Laboratories Zener Diode Tutorial. Confused about zener diodes and how they work? Read this.

Monitor your Ham Radio transmitter with an oscilloscope. In this video, Alan, W2AEW builds a little adapter that lets you connect your transmitter output to a scope input so that you can see how clean its output is.

Keep electronics safe from static discharge

Electrostatic discharge, or ESD, is perhaps the biggest danger to integrated circuits, and electronics companies spend millions of dollars each year on products to reduce static buildup and discharge and to test how susceptible their ICs are to ESD. Simliarly, when building a kit, or working on electronics that are ESD-sensitive, it’s a good idea to use a conductive  mat on your work surface and a wrist strap connected to earth ground. I use both in my shack.

Texas Instruments has a number of videos on their website that will give you a better idea why this is a good idea. They’re mostly designed to sell you their ESD protection devices, but unless you’re designing electronic systems, you can mostly ignore the sales pitch.


How the Transistor Got Its Name

I’ve been a ham radio operator a long time, and I even have an electrical engineering degree, but I never really knew how the transistor got its name. Well, according to this post on the Adafruit blog, they actually took a vote. The entire memo has been posted to flickr.

While searching around for a picture of the first transistor, I found the video, “Does the first transistor ever built still work?” It explains how it works, and you can actually see the transistor, which is now part of the collection at the University of Illinois Spurlock Museum.

The Shack to Get Back Into Parts Again?

From the 6/2/11 ARRL Letter:

In the Shack: RadioShack Looking for Suggestions for DIY Parts

Back in the day, RadioShack was the first place many of us looked for parts. QST construction projects routinely referenced RS part numbers, and the Shack even sold 10 and 2 meter transceivers. What goes around comes around, and RadioShack is now looking for input from us, as members of the larger DIY community, on parts we’d like to see them carry. There’s a video explaining what they’re looking for, and a place to add comments.

Now, before you all start complaining that there going to charge double for whatever it is that they will carry–and they probably will charge double for it–consider that you’ll at least be able to get the parts you need when you need them.

Using Op Amps for Small-Signal Audio Designs

EE Times has started running a series of articles on using op amps as audio amplifiers. Taken from the book, Small Signal Audio Design, Part 1 discusses the history of op amps and then looks at various op amp properties from a perspective of audio design. Looks pretty interesting to me.

So, When Can I Get a 100 W HT?

From the 4/1/11 issue of ACM Tech News:

The Incredible Shrinking Circuit
University of Cambridge (03/28/11)

University of Cambridge researchers have developed a technique for producing smaller microchips that can also support extremely high electrical current densities. Led by Cambridge professor John Robertson, the researchers used carbon nanotubes to replace the vertical copper connectors in integrated circuits to build smaller circuits and to reduce the size of electronics even further. They took advantage of the special arrangement of carbon atoms. Normally the atoms are arranged hexagonally and layered in sheets, but in nanotubes the sheets are rolled up to form tiny tubes with diameters equivalent to just a few carbon atoms. To make the approach feasible, the nanotubes would need to be grown in very dense bundles directly onto the substrate. Robertson and colleagues used multiple deposition and the annealing steps to grow nanotube bundles, and the method led to successive increases in nanoparticle density. The researchers say the density of the bundles is five times greater than current technology.

View Full Article

Links for the New General Class Study Guide

For the next version of No-Nonsense, General Class License Study Guide I am going to include links to Web pages that readers can refer to if they really want more information on a topic. I’ve just added some links to the following sections:

If you have other suggestions, I’d love to hear about them. Please send me the URLs and why you happen to like that particular website. Thanks!

From the Trade Mags

I’m on the distribution list for many different electronics trade magazines. Quite often, there are articles of interest to amateur radio operators. Here are four of them—two from electronic design and two from EE Times—that I hope you’ll find interesting.

Radiated efficiency: A true measure of antenna performance
Many engineers tend to think of antennas in terms of gain, but the author argues that we’d be better off if instead we evaluated antennas in terms of efficiency, that is how well it turns the power supplied to the feedpoint into radiated energy.

And You Thought The 555 Timer Was Dead?
Recently, both Advanced Linear Devices and Semtech have redesigned the 555 timer chip, improving it in many ways and extending its usefulness—most likely—for years to come.

Melville Eastham: Workplace Innovator Crafts Early Electronic Products
Eastham was the founder of General Radio. The article points out that Eastham founded the company in 1915 to “serve the rapidly growing ham radio market.” By the late 1920s, that “boom” had subsided, and the company turned its attention to precision measurement instruments. It was very successful doing this for many, many years.

10 Technologies to Watch in 2011
This article predicts that “wireless connects for health care” will be one of the technologies to watch in 2011. Makers of medical electronics equipment, apparently, are planning to integrate their gear using Bluetooth.

Analog-to-Digital Converter Targets Wireless Applications

This from the press release for the AD9467, an analog-to-digital converter, capable of 16-bit conversions at data rates up to 250 MHz:

Norwood, MA (09/27/2010) – The industry’s fastest 16-bit ADC (analog-to-digital converter)–at 250 MSPS (mega samples per second)–was unveiled today by data converter market share leader* Analog Devices, Inc. (ADI). The AD9467 16-bit, 250 MSPS ADC operates on 35% less power at 25% higher sampling rate than any other 16-bit data converter, providing a new level of signal processing performance for test and measurement instrumentation, defense electronics, and communications applications where high resolution over a wide bandwidth is needed.

The AD9467 delivers resolution and a fast sample rate while simultaneously achieving a high SFDR (spurious-free dynamic range) of up to 100 dBFs and SNR (signal-to-noise ratio) performance of 76.4 dBFS. The device’s SFDR of 90 dBFS up to 300 MHz analog input and 60-femtosecond rms (root mean square) jitter helps lower the signal chain bill of materials component count by allowing engineers to increase system performance at higher intermediate frequencies, thereby reducing the number of signal down-conversion stages. Download data sheet or order samples and evaluation boards.

The AD9467 can be used with ADI’s AD9523/24 low-jitter clock generators and ADL5562 3.3 GHz ultra-low distortion RF/IF differential amplifier to provide a data conversion signal chain solution.

AD9467 16-bit, 250 MSPS ADC Key Features and Benefits:

  • 16-bit resolution with high signal bandwidths up to 300 MHz enables advanced signal acquisition subsystems in common radio platforms, radar systems, and spectrum analysis.
  • On-chip IF (intermediate frequency) sampling circuit and buffered analog inputs optimize the AD9467 for the highest ENOB and ease of use.
  • High dynamic range over broad signal bandwidth enables software-defined radios for use with multiple standards, such as LTE/W-CDMA, MC-GSM (class 1) and CDMA.
  • Programmable full-scale input range allows trade-off between SNR and SFDR enabling the design of more sensitive radar systems with the ability to acquire and track smaller targets with better accuracy.

The 200MHz part will cost $100 in quantity, while the 250 MHz part will cost $120.

Can anyone say “software-defined radio”??