Copasetic Flow

I started building up the RockMite 20 m CW transceiver yesterday. This is a great little kit and a great little project. I've been working in the logic design industry for the last fourteen years on projects like the Pentium, and the K5 and K6 processors. My part of these projects was done completely in simulation. Consequently, I haven't built a real board project in all that time. So, even though I suppose it should seem commonplace to me, I'm floored that for about $25 you can get a radio with an integrated receiver, transmitter, and a micro-controller that all fits on a board that's maybe 3" x 2"! The first component I installed was the NXP SA612A double balanced mixer and oscillator shown below. Here's the datasheet for this little guy [pdf]. It's used in the receiver section to strip the carrier from the received RF signal leaving only the audio to be amplified and sent to the headphones. You can read more about the heterodyne and demodu...

My Advanced ham license slipped back in 2002. With the physics study I've been involved in lately, it seemed like a good time to get back into the hobby. Calculating the distribution of an electromagnetic field has a little more concreteness to it when your antenna design depends on the result. So, I studied up, and recently passed my General exam. All that studying is what inspired the set of practice exams that appeared on this site recently. My old boat anchor radio went the way of my Advanced ticket a few years back, so I recently ordered a QRP rig, the 20m RockMite from Small Wonder Labs . It's a small CW-only transceiver kit that looks pretty slick. I got a great surprise this afternoon when my General ticket and the RockMite kit came in the mail on the same day! I'll be writing here about the construction and operation of the RockMite as the project moves along. In the mean time, does anyone have a good design 20m antenna design that can be deployed from a...

Go take a practice test now using the links below! Technician General Extra Now, when you practice for your amateur radio, (ham), exams you can track your progress and find out which test subelements you need to spend the most time on. Just create a user name using the login box: The user name is used to track your test scores. After you have practiced a test, you should see results similar to those shown below. The first chart shows all of your test scores. The second chart shows how you're doing on each test subelement. Use the second chart and the table below to determine which subelements to spend your time studying. Coming soon: practice tests focused on specific subelements. 73 and have fun! KD0FNR

Ham Radio Practice Exams from KD0FNR Basic | Advanced Technician | General | Extra More Great Stuff from Copasetic Flow Ham Radio Physics Programming Funny Adventure

The amateur radio license exam practice applications on this site offer two features. First, they provide practice exams randomly constructed from the actual examination question pools. Second, as each exam question is displayed, study materials related to the question are displayed as well. The practice exams can be found at: Technician Class Exam General Class Exam Extra Class Exam Exam Practice Instructions The exam practice screen is shown above. A question is presented along with four multiple choice answers. A correct answer will be highlighted in green. If the wrong answer is selected, it will be highlighted in red. Additional answers can be selected to determine the correct answer, but only the first selected answer will count in the test score. If exam question requires a figure, it will be shown below the multiple choice answers. Study Material Instructions As each question is displayed, related study material may be displayed in the 'Available Study Material secti...

One of the first things I always find myself doing when writing an application using the Google Visualization API Query Language is writing a simple application framework to test out my data models and queries. Rather than re-inventing the wheel on every project, I decided to just implement a simple tester here where, hopefully, everyone else can benefit from it as well. To use it, simply place the datasource URL you intend to use as well as the query string in the appropriate blanks below. Then click, 'Test Query' to see the results of the query. For example, you can try the datasource URL and a query string from the Hierarchical Chooser post. datasource URL: http://spreadsheets.google.com/pub?key=pvFXGB-79Kl2d6jU-_m44ZQ&gid=0&pub=1 Query String: Select A, B, C Datasource URL Query String

Writing about physics and specifically electromagnetism got me to thinking about amateur radio. In the United States, any person can receive an amateur radio license that allows them to transmit and receive on a number of frequencies allocated by the FCC. Amateur radio is a great hobby. People involved in the hobby, (called amateur radio operators), get a chance to turn their EM knowledge into concrete experience by building usable radio transceivers and antenna structures. To get a license, operators must first pass a written test on radio operations fundamentals, engineering, and FCC regulations that apply to amateur radio. The question pools used for the exam are available online as are practice tests. I thought it would be fun to build an application that would construct practice tests on this blog. The final application will provide practice tests similar to the ones at qrz.com but, with a bit more interactivity. This series of articles will cover the construction of t...