Back To Basics: Voltage Measurement

How is a voltmeter usually connected to a circuit under test?

Question B-005-013-001 - From The Canadian Basic Question Bank

A handy thing to know, particularly as basic digital multimeters (DMMs) are now very inexpensive, usually less than $10., and can be useful for many things around the home like checking the condition of batteries.

The two types of voltmeter you may encounter are digital and analog.  Analog meters are recognizable by their printed scale and a moving needle. 

Voltage is always measured in parallel with a device, current in series. If you recall Ohm’s Law in your (Canadian) Basic Qualification, you will remember series, parallel and series-parallel circuits. If not, check this link:  http://www.physicsclassroom.com/class/circuits/Lesson-4/Two-Types-of-Connections

On the meter, first set the knob to a voltage range greater than the expected voltage. If you don’t know what to expect, set it to the highest range.  DC Voltage range has a V- with a straight line next to it, AC generally a V~ with a wavy line. For example, 2V measures voltages up to 2 volts, and 20V measures voltages up to 20 volts. In our circuit the meter is hooked up in parallel to measure the voltage of the component under test.

The correct answer therefore: In parallel with the circuit.

~ John VE7TI

Earth At Night!

A Free NASA eBook 

Earth at Night, NASA’s free new 200-page eBook in three formats, is now available online showing our planet in darkness as captured from space by Earth-observing satellites and astronauts on the International Space Station over the past 25 years.

Aside from the fascinating photos, there are explanations of Earth's weather as well as the Aurora and other phenomena of interest to the Amateur Radio Community

https://www.nasa.gov/connect/ebooks/earthatnight_detail.html

A SARC Basic Course Retrospective

A Message From A Successful Teen Ham

Hello, readers. I’m Samantha, I’m sixteen years old, and this May I got my amateur radio basic license - with honours, too. Finally entering the world of amateur radio came with a lot of passion, learning, and a bit of studying, and having a gate wide open to another enormous world of learning is perhaps one of the things about having a license I’m most excited about. Though I’m proud about my achievement, I have to thank Surrey Amateur Radio Communications Basic radio course for my success.

Sammi and Member of Parliament Sukh Dhaliwal
at Field Day 2016

SARC sets up a course so amateurs-to-be can prepare for their license test. It went through all the topics we needed, through on-air etiquette and the long list of laws, among more interesting things like electric theory and propagation (man, those are fascinating topics). However, what I appreciated most in the course was the caring environment, where asking questions, talking with others, and even joking around a little is perfectly normal. 

I felt very welcome in the class – though being the only girl in the class was a little disappointing – and I especially want to thank John VE7TI, Stan VA7NF, and John VA7XB for all being incredibly knowledgeable, kind, and personable. It helps when a learning environment is friendly; I don’t think I could learn if it isn’t. In fact, it’s wonderful that amateur radio in general is so friendly to everyone.

Noah, age 13, a graduate of our Fall 2019 course,
at 27 students, our largest class ever.
His dad [right] who also graduated from this class,
and one of the instructors John VE7TI

See, the thing about the world of amateur radio is that it’s just so big. If you don’t like one aspect of it, there’s going to be another that piques your interest. Plus, it’s not just a hobby for one type of person or one type of community. Anyone, and yes, I mean anyone, can get a license. Doesn’t matter if you’re old or young, male, female, neither, or both; what matters is that amateur radio is interesting to you, even if it’s just digital radio or only using a phone mode. My hope is that other teens like me discover this community and, like me, fall in love with it and all it has to offer, because this world isn’t dying. As long as we’re around, we’ll make sure to let it thrive.

~ Samantha VA7HBE

Our next course starts February 25, 2020 at 6:30pm

For more information email: course@ve7sar.net

Our Field Day Success!

Another First For The SARC-SEPAR Team

We just got the results from 2019 ARRL Field Day, VE7SAR achieved top score in Canada (again) for 3A. Great work and congratulations to the SARC & SEPAR team members.

How did we accomplish this again?

Our planning this year followed the Incident Command System (ICS), a structured means of planning and staffing a large event. Our ICS approach to planning was described in detail in a previous post.

Electronic Magazines?

The Local Library Can Probably Meet Your Need

For some time I have had a electronic subscription to the magazine service called Next Issue. This cost me about $9.95 a month, but I’ve made a great discovery.

Would you like to receive the current and back issues of ‘CQ’ amateur radio magazine for free? Well you can, plus almost three-hundred other retail magazines covering a wide variety of subjects and interests. How? Well do you have a library card? If not, you can get one for free at your local library. Once you have it, in our city just go online to https://www.surreylibraries.ca/books-media#B (or your city library depending on your locality) and look for the link to the eLibrary. Once there, click on Zinio Digital Magazines.

Once there you'll see not only CQ magazine but Popular Mechanics, Popular Science, many computer and woodworking magazines and lots more.  A video tutorial is at https://vimeo.com/118833746.

Current Issues — New issues are released simultaneously with the print edition. Many are available before they arrive at your library and are ready for immediate download.

Back List — As your collection grows, so does the digital library for anytime checkout and reading.

Easy browsing and checkout — Browse your library's collection of titles one at a time, search for your favorite magazines by title or use the convenient category feature to find new magazines which meet your interests.

Manage your collection — Using the personal account you create, you will have the opportunity to checkout magazines and read them instantly on your computer or access the content on a portable media device.

I use an iPad for my reading and Zinio has a dedicated app. There is also one for Windows and Android devices and for most popular eBook readers. There is no limit to the number of magazines you can download nor is there a limit how long you keep them. No waiting list or reservations. When you're done with them just delete them from your device. If there is something I want to get I make a screen grab. There is a request form for new magazines to be added… perhaps if enough of us ask we can get some additional Amateur Radio publications.

I hadn't been to a library in months but, thanks to Norman Schmidt VE7IIT, whom I followed into the library after a recent breakfast, I made this marvelous discovery. I can now sit back in my easy chair and read more magazines than I could justify subscribing to. I even get an email when my favorite magazines publish a new issue.

~ John VE7TI

Make Your Own Single-layer Air-core Coil

Information and examples to make practical single-layer air-core coils.

Whenever you are working on an RF filter, choke, antenna or an oscillator design, most likely you will need a coil. Under some circumstances, the coil might not be available commercially or may be expensive. If this is the case, you have to make your own. This article will provide the information and examples to make practical single-layer air-core coils.

The well known Wheeler’s formula is used to calculate the approximate inductance of a single-layer air-core coil.  In 1925, Harold A. Wheeler published his formula as shown below. This is not a theoretical formula but an empirical one and is accurate to 3~4%.

Where:

     L: inductance (μH)

     d: diameter of coil (inch)     
     n: turns of winding                    
     l: length of coil (inch)

For best result by using this formula, the length of the coil (l) should be equal to or greater than 40% (0.4) of the coil diameter (d). If you study the formula carefully, you will find that the inductance is proportional to the square of the turns. That is, if you want to double the coil’s inductance, you don’t have to double the turns, you just add 40% more turns to the coil. For example, if you have a coil of 47μH and the winding has 100 turns, and you want to double the coil’s inductance to 94μH, you simply add another 40 turns to it, for a total of 140 turns.

Example 1: What is the inductance of a coil if the coil has 86 turns wound on a 1.25 inch diameter round form, and the coil’s length is 1.5 inches? In this case, d = 1.25,  l = 1.5 and n = 86.

Since the input data are only good to (at most) 3 significant figures, the result is only good to 3 figures so you would round the answer to 140µH.  To calculate the number of turns of a single-layer air-core coil for a given value of inductance, re-arrange the formula and it becomes:

Example 2: To build an AM radio, an inductance of 260μH is required. The form on which the coil is to be wound has a diameter of two inches and one inch is chosen to be the length of that coil. Then d = 2 inches, l = 1 inch and L = 260.

Since the coil is 1 inch long, the number of turns per inch is 70 / 1 = 70. Consulting the chart at the end of this article, we find that 28 AWG enameled wire can be used.

To make it easy for you to build your single-layer air-core coil, the author has written a script with PHP to do all the calculations for you. All you have to do is just plug in the desired inductance, the diameter of the coil form, the wire gauge and, if wanted, the operating frequency (for the Q or quality factor of the coil). Then you will be given the number of turns of the coil, the length of the coil and the length of wire needed. Since you know the length of the coil, you just wind the coil tightly to that length, which saves you from having to count the turns.  I hate to do the counting because it is tedious and frustrating when you lose count, believe me. You can fool around with the diameter of the coil form and/or the wire gauge to optimize your coil.

I’ve placed the script on our website.  You can try it out from the link below.

http://www.ve7sar.net/CoilCalculator/CoilCalculator-en.php

The above picture shows the final product of the example 2 in this article.

The coil is wound with 28 AWG enameled wire on a 2 inch diameter pill bottle. 

254μH is measured, which is 2.3% less than the target value 260μH. 

This result is more than adequate for most applications.

Have fun on winding and I hope this has been useful.

~ Hiu VE7YXG

Morse (CW) Teaching Software

A Variety Of Apps To Help You Learn Morse Code

We are offering a Morse Code class starting January 20, 2020

In the meantime, there are now a wide variety of apps and programs to assist you in learning CW.

Morse Toad  is an app that teaches Morse code through a series of simple lessons and exercises. Based on the proven Koch method, letters are learned one at a time, at full speed, and when the player demonstrates their mastery of the new letter, another is added until the full alphabet is learned. The Apple iOS version is shown but Android is also available. This is the one I’ve had the most success with refreshing my rusty CW, though the interface looks a bit old school.

WinMorse My choice for Windows computers. Convert text into Morse code. It does this by reading text from one of three sources: the Windows clipboard, a file, or you may directly type the text. WinMorse outputs the Morse code as a standard windows wav file.

MorseCat A freeware windows Morse code trainer for beginners and experts by DK5CI.

Code Quick Master Code In 30 Days it says... Maybe.

Super Morse Super Morse is the original comprehensive Morse Code training program for the PC. Super Morse permits the user to learn the Morse characters in a very orderly way using several different methods, including one unique to Super Morse; build speed with special exercises.

CWT a Morse code learning program for MSDOS by DK5LI.

CW Player Simple freeware program generates Morse characters and Q codes. It needs a sound card and Win95.

Morse99 the industry standard Morse code tutorial for pilots in the UK. Fully windows compatible with sound card support.

Ham University Ham University includes Morse Code lessons, graded exercises, and a game.

Morse Code Morse Code Training, Practice and Exam Program by Stormy Weather SoftWare Ltd.

RufzXP RufzXP is a free training software for improving code speed and CW practice, particularly (ultra) high speed memory copying of true amateur radio calls.

Morse Academy Online documentation and overview about Morse Academy, shareware CW learning software.

Codemaster V Reputation as the Morse code training package for either the newcomer to Morse code, or the experienced user who wants to improve his or her receiving skills.

Morse Pilot Morse Pilot is a popular and very comprehensive freeware Morse code tutor, trainer with decoder and encoder functions. Morse Pilot is intended for personal training, for example for radio ham or aviation examinations.

MorseRunner (Contest simulation with N1MM logger) Teaches and simulates CW contacts in a contest environment including noise, band conditions and various operating speeds.

Koch Method CW Trainer Based on the Koch Method as described by David G. Finley, N1IRZ, this software allows you to start out at the full speed you want to achieve by learning two letters and adding an additional letter once you reach 90% proficiency.

You may also want to checkout this blog post by Wayne K5UNX about learning CW https://www.amateurradio.com/cw-part-3/ 

You can get free online lessons and exercises at https://lcwo.net/ 

And, here from Norway, good reasons to learn CW

Morse code is no longer a requirement to acquire an amateur license here in Norway. The same is true for many (or most?) other countries. Still Morse code, or CW – continuous wave as it is often referred to as, has great value. Here are my top five reasons why I am learning Morse code.

1 – Excellent propagation
Voices are long gone and all you hear is static. Tune down to the lower end of the band and you will probably still hear dah-di-dah-dit dah-dah-di-dah. When “the bands are dead” as they say, the one thing you can still hear is CW. The propagation abilities are extreme.

2 – Power efficiency
Since all the radiated energy is concentrated in one single tone, morse code is an efficient form of communication with regards to power. This means that morse code is good for QRP use, or even QRPP. Also you do not need equipment that can handle large amounts of power. Thin wires and small components are enough to be heard around the globe.

3 – Easy to build kits
Small currents and simple signals do not need as advanced circuits as single sideband or FM do. There are several circuit diagrams and kits available to build, and many choose to design their own transceivers.

4 – Ultra portable transceivers
Morse code is great for SOTA and outdoor use. Small form factor kit transceivers kan fit in a small tin or plastic box, and other commercial lightweight CW only transceivers are available. When you need to bring other equipment like your tent, sleeping bag, clothing and food it is nice to bring a transceiver that does not add significant bulk and weight to the backpack.

5 – Easy way to get on the air for non-talkers
Many of us are the non-talking kind of person. I do enjoy an occasional rag-chew now and then, especially on the local 80 m net, but for now I prefer the “exchange vital information and move on” kind of style. It seems there are more of this kind of QSOs with CW.

6 – Awesome-factor

Bonus reason: Morse code has this nerdy awesome-factor to it. Morse code is something everyone recognize, but not many understand it. It truly is impressive to watch someone perform high speed CW.

~ John VE7TI