Excel-Based Calculator Models Transmission Lines

This Excel-based tool calculates the capacitance and inductance per unit length as well as the impedance of a transmission line. It may be applied to wires, PCBs, etc.

This spreadsheet uses macros, so it didn’t work with my Mac’s Numbers program, but it did seem to work with the NeoOffice spreadsheet program.

ARRL Member Can Now Access All QSTs from December 1915 to December 2004

From the ARRL:

With just a mouse click or two, ARRL members can now access the online QST magazine archive. This new benefit — a service of the ARRL Technical Information Service (TIS)—provides PDF copies of all QST articles from December 1915 through December 2004, enabling members to view and print their favorite article, project and more. For many years, the TIS has provided members with assistance researching ARRL periodicals and publications, as well as providing members and non-members with article reprints for a small fee. Access to the new online digital QST archive is free for ARRL members

“Having access to every issue of QST through 2004 is absolutely incredible!” said ARRL Lab Manager Ed Hare, W1RFI. “The best of the best of QST from every era is now at the fingertips of every ARRL member with a keyboard and an Internet connection. Members can research articles on any subject that interests them, or just browse the past issues. This will be a popular membership benefit that will be of special value to new and long-time hams alike. This valuable content will help radio amateurs who use QST as a technical resource — for projects, equipment ‘hints and kinks’ — and for other research contributing to the advancement of the radio art. We know many hams will simply enjoy perusing these pages of history, too.”

The archive delivers indexed content (articles, columns, projects and more) as black-and-white PDF images of QST pages — just as they were originally published. While the index contains an immense amount of searchable material, some content (such as advertisements) are not yet indexed. A full-text search is not available.

The QST archive is the latest in a long list of members-only benefits available via the ARRL Web site. Access to members-only Web features does require a simple registration. Once logged in, members can access the QST Archive, product reviews, subscribe to online newsletters and manage changes to their membership and QST magazine delivery address. Many members also enjoy the popular ARRL E-mail Forwarding Service (“your call sign”@arrl.net).

The ARRL Periodicals Archive and Search lists every article for QST from 1915 to the present, QEX from 1981 to the present, Ham Radio from 1968 to 1990 and NCJ from 1973 to the present (please note that beginning in 1998, each issue of QEX covers two months). Only ARRL members will be able to download and print copies of the QST articles.

QST magazine is the official journal of ARRL, the national association for Amateur Radio. An interest in Amateur Radio is the only essential qualification of membership. ARRL membership is $39 per year in the US. For a complete list of membership benefits and dues, please visit the ARRL Membership Web page.

Kudos to the ARRL for doing this.

Success with RUMTrol

I’ve noted before that one of the disadvantages of using a Mac in the shack is the lack of software. Fortunately, Tom, DL2RUM, has come to our rescue. His programs, RUMLog and RUMTrol, are really great programs. Oh, and did I mention they’re free?

About a week ago, I decided to get RUMTrol working. Instead of kludging together the USB-RS232 converter, followed by the RS232-CIV converter I built a couple years ago, I decided to purchase to but a USB-CIV cable. After reading some positive comments online, I bought the Radio Shack 20-047 Scanner Programming Cable. Unfortunately, it took quite a bit of futzing to get this to work properly.

First of all, I had to get the proper driver. Without this driver, RUMTrol couldn’t even see the port. A guy on the Ham-Mac mailing list pointed me in the right direction for this driver, which I downloaded from the FTDI website (www.ftdichip.com).

At this point, I could program RUMTrol to send data to the radio, but it wasn’t reading any data from the radio. I tried a bunch of different settings, but without any success. The frustrating thing about all this is that the radio seemed to be sending the data (at least that’s what I took the flashing lights on the cable to mean), but the computer wasn’t receiving it.

I posted a query to the RUMSoft bulletin board, and after a few go-rounds, Tom, DL2RUM, was able to set me straight. The problem seemed to be my choice of baud rate – 300 baud. My thinking was that if I could get it to work properly at the slowest baud rate, I could then jack up the baud rate so that it would work faster.

Wrong! I never did get the received at 300 baud, but after DL2RUM suggest that I set the baud rate to 9600 baud everything started working. I’m puzzled, but happy.

Snap Circuits for Adults

SnapCircuits are electronics kits designed for kids (although adults have fun with them, too!). Components, such as resistors, capacitors, motors, transistors, and LEDs are mounted on plastic bases that snap together. The manuals that come with the kits describe a number of different circuits that are both fun and educational.

Now, for adults there’s littleBits. The website has a short video on the concept and this text:

littleBits is an opensource library of discrete electronic components pre-assembled in tiny circuit boards. Just as Legos allow you to create complex structures with very little engineering knowledge, littleBits are simple, intuitive, space-sensitive blocks that make prototyping with sophisticated electronics a matter of snapping small magnets together. With a growing number of available modules, littleBits aims to move electronics from late stages of the design process to its earliest ones, and from the hands of experts, to those of artists, makers and designers.

Stay tuned, design files, schematics and instructions will be online soon

Ambitious, no? I do like it that the designs will be open-source and the way the modules connect magnetically, but without more detail it’s hard to say how easy or difficult it will be to use these things.

There’s also a question of whether or not there will be processor “bits” and how these processors are to be programmed. I can’t imagine they haven’t thought of that yet, but there’s such little detail on the website, it’s hard to say for sure. If they’re smart, and Bdeir is an MIT graduate so presumably she is, they’ll adopt one of the small processor designs, such as the Arduino, that’s become popular in the maker community.

Anyway, they have a mailing list, that I just subscribed to, and hopefully there will be more details forthcoming soon.  I’ll update when I know more.

Bye Bye, Birdies

Yesterday, I installed a wireless router here. Now, I not only have wireless networking throughout the house, but the two birdies around 14.030 MHz are gone! I was living with them as I didn’t want to turn off the router while operating, but now that’s a moot point.

One thing I found kind of puzzling about the birdies is that sometimes they would be stronger than others. I guess that could be the result of different amounts of traffic on the net. Any thoughts?

NIST Improves Printable Semiconductors

From the 9/3/08 issue of NIST Tech Beat:

Researchers from the National Institute of Standards and Technology (NIST) and Seoul National University (SNU) have learned how to tweak a new class of polymer-based semiconductors to better control the location and alignment of the components of the blend. Their recent results—how to move the top to the bottom—could enable the design of practical, large-scale manufacturing techniques for a wide range of printable, flexible electronic displays and other devices.*

drawing of organic semiconductors

Restacking organic semiconductors: An improved formulation for a polymer blend semiconductor causes key semiconducting molecules to migrate to the bottom of the active layer, allowing chip designers to replace top-gated structures (a) with more easily manufactured bottom-gate, bottom-contact devices (b).

Credit: Yoon, SNU
View hi-resolution image

Organic semiconductors—novel carbon-based molecules that have similar electrical properties to more conventional semiconducting materials like silicon and germanium—are a hot research topic because practical, high-performance organic semiconductors would open up whole new categories of futuristic electronic devices. Think of tabloid-sized “digital paper” that you could fold up into your pocket or huge sheets of photovoltaic cells that are dirt cheap because they’re manufactured by—basically—ink-jet printing.

The problem is performance. Small organic molecules have been developed with key electrical parameters close to the benchmark set by amorphous silicon semiconductors, but they are very difficult to deposit in a stable, uniform film—a key manufacturing requirement. Larger molecule polymer semiconductors, on the other hand, make excellent thin films but have at best limited semiconductor properties. A patent from British researchers in 2005 offered a promising compromise: blend the small semiconductor molecules in with the polymer. This works surprisingly well, but with an asterisk. Tests showed that actual devices, field effect transistors, made with the blend only worked well in a so-called “top-gated” structure. The critical active part of the film was on the top, and the switching part of the device (the “gate”) had to be layered on top of that, a process difficult or impossible to do on a large scale without destroying the fragile film.

Working at NIST’s Center for Neutron Research, the SNU/NIST research team used a neutron imaging technique that allowed them to observe, with nanometer resolution, how the distribution of small organic semiconductor molecules embedded in polymer films changed with depth—the films are less than 100 nanometers thick. In the thin films originally described by the patent, the bulk of the semiconductor molecules end up at the top of the film, as suspected. However, when the SNU/NIST research team substituted a polymer with significantly higher molecular mass, something interesting happened. The organic semiconductor small molecules distributed themselves evenly at the top and bottom of the film. Having an active region of the film on the bottom is key for large-scale manufacturing because it means the rest of the device—gate, source, drain—can be laid down first and the delicate film layer added last.

In addition, they report, the optimized blend of polymer and organic semiconductor actually has better performance characteristics than the organic semiconductor on its own.

* J. Kang, N. Shin, D.Y. Jang, V.M. Prabhu and D.Y. Yoon. Structure and properties of small molecule-polymer blend semiconductors for organic thin film transistors. Journal of the American Chemical Society, Published on the Web Aug. 23, 2008.

I can’t wait until printable semiconductors becomes real. I think it will breathe new life into experimenting and homebrewing.

No Sunspots for More than a Month!

Daily Tech reports that it’s now been more than a month since a sunspot was sited. This is the first time that this has happened in more than 100 years. The article notes:

In the past 1000 years, three previous such events — the Dalton, Maunder, and Spörer Minimums, have all led to rapid cooling. One was large enough to be called a “mini ice age”. For a society dependent on agriculture, cold is more damaging than heat. The growing season shortens, yields drop, and the occurrence of crop-destroying frosts increases.

No mention was made of poor band conditions on 20m <grin>