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Sunday, November 24, 2019

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




Thursday, November 21, 2019

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.



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



Sunday, November 17, 2019

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







Thursday, November 14, 2019

Emergency Amateur Radio Support Across Canada



How well is amateur radio for emergencies supported by governments across Canada?
While looking online for inspiration for this months Communicator, I began to notice that there weren't many results when I googled certain word groups regarding governments, amateur radio, and emergencies. So that got me wondering what type of support different Provinces give to their Amateur Radio ARES groups and where British Columbia fits in. Yes, I know SEPAR isn’t a typical ARES group, because we serve the City of Surrey first and foremost, to provide a communications link between the City and services within the City whose communications has failed. But that, in my view, is just an ARES group with a twist. 

The results I discuss below are based on my Google search parameter of “amateur radio emergency [Province name or City name]”. As I discuss this please remember, I’m talking about the support shown for amateur radio on government websites and not Radio Amateurs of Canada websites. There is no shortage of RAC and local club support for emergency communications in Canada.

BC, as you may know, has PERCS (Provincial Emergency Radio Communications Service) which is strongly integrated with the BC Government. The Emergency Radio Communications webpage of the BC government also lists Amateur Radio as a source of emergency communications. Several municipalities in BC actively support their Amateur Radio, for example - SEPAR in Surrey, and VECTOR in Vancouver. In the other jurisdictions, outside BC, there does not seem to be this support from government. 

In Ontario, it seems more of a passing thought (at least when looking through the government websites). EmComm (Emergency Communications Ontario Association) lists Emergency Management Ontario as a support site, but Emergency Management Ontario, which is the governments site, does not reciprocated to EmComm. The City of Toronto in their emergency plan does include amateur radio, but it’s hidden in a PDF document and not referred to on their City website like SEPAR is in Surrey.

In Alberta, Edmonton mentions Amateur Radio briefly on their City website. Calgary also mentions amateur radio on their City website but only to recognize that antenna structures need to have controls put on them. Nothing is said about the benefits amateur radio can provide in a disaster.

The province of Quebec has 4 words (3 words when translated to English) as a mention on the government website -“réseaux de radio-amateur” [Amateur Radio Networks]. This is under the heading of “Les partenaires de la municipalité” [The Partners of the Municipality] on their webpage discussing the role of municipal partners during an emergency. 

I couldn’t find any reference on provincial websites in Nunavut, Newfoundland, Saskatchewan or Manitoba.

Nova Scotia makes no mention of the role amateur radio would play in the provincial plan, but as a slight aside, there is a very good article on one of their journalism pages. It explains the benefits of Amateur Radio and how it was used during the crash of flight 111 in Peggy’s Cove.

The Northwest territories like the City of Toronto only speaks of Amateur Radio in their Emergency Plan, which is again a PDF document. The discussion in the NWT plan only suggests that Amateur Radio should be part of the plan. 

The Yukon Territory does mention amateur radio, and if their is integration with the government, I couldn’t find it on their web pages. 

It’s a stark difference to BC where the Province links to PERCS and municipalities link to their Emergency Amateur Radio providers like SEPAR, VECTOR, Coquitlam, North Shore Emergency Management, etc.

It seems to me that it is important for the public to be aware of the inclusion of Amateur Radio in their emergency plans. While it’s important to be written into the Emergency plan, most residents will never read that document. Many will read about it however, if it’s published on the government websites, with a brief explanation of the benefits. Ideally, neighbourhoods should even be aware of the location of a neighbourhood ham operator so that they know they have a communicator at their disposal in an emergency. As it stand right now, at least in BC and Surrey especially, we are prominently integrated in emergency plans. Something I can’t say for the majority of the country. 

~ Roger VA7VH





Saturday, November 9, 2019

Harmonic Radiation

Back To Basics


From the Canadian Basic Question Bank

Back To Basics is a regular column in the SARC Communicator Newsletter, available on this blogsite.

B-003-001-003
In designing an HF station, which component would you use to reduce the effects of harmonic radiation?

A. Dummy load 
B. Antenna switch 
C. SWR bridge
D. Low pass filter

The term harmonic is employed in various disciplines, including music and acoustics, electronic power transmission, radio technology, etc. It is typically applied to repeating signals, such as sinusoidal waves. A harmonic of such a wave is a wave with a frequency that is a multiple of the frequency of the original wave, known as the fundamental frequency. The original wave is also called the 1st harmonic, the following harmonics are known as higher harmonics. For example, if the fundamental frequency is 60 Hz, a common AC power supply frequency, the frequencies of the first three higher harmonics are 120 Hz (2nd harmonic), 180 Hz (3rd harmonic), 240 Hz (4th harmonic) and any addition of waves with these frequencies is periodic at 60 Hz.

Spurious emissions

Early in the development of radio technology it was recognized that the signals emitted by transmitters had to be 'pure'. Spark-gap transmitters were outlawed once better technology was available as they give an output which is very wide in terms of frequency. The term spurious emissions refers to any signal which comes out of a transmitter other than the wanted signal. In modern equipment there are three main types of spurious emissions: harmonics, out of band mixer products which are not fully suppressed and leakage from the local oscillator and other systems within the transmitter.
Harmonics
These are multiples of the operation frequency of the transmitter, they can be generated in any stage of the transmitter which is not perfectly linear and must be removed by filtering.

Avoiding harmonic generation

The difficulty of removing harmonics from an amplifier will depend on the design. A push-pull amplifier will have fewer harmonics than a single ended circuit. A class A amplifier will have very few harmonics, class AB or B more, and class C the most. In the typical class C amplifier, the resonant tank circuit will remove most of the harmonics, but in either of these examples, a low pass filter will likely be needed following the amplifier.
Removal of harmonics with filters
In addition to the good design of the amplifier stages, the transmitter's output should be filtered with a low pass filter to reduce the level of the harmonics. Typically the input and output are interchangeable and match to 50 ohms. Inductance and capacity values will vary with frequency. Many transmitters switch in a suitable filter for the frequency band being used. The filter will pass the desired frequency and reduce all harmonics to acceptable levels.

The harmonic output of a transmitter is best checked using an RF spectrum analyzer or by tuning a second receiver to the various harmonics. If a harmonic falls on a frequency being used by another communications service then this spurious emission can prevent an important signal from being received. Sometimes additional filtering is used to protect a sensitive range of frequencies, for example, frequencies used by aircraft or services involved with protection of life and property. Even if a harmonic is within the legally allowed limits, the harmonic should be further reduced.

Oscillators and mix products

When mixing signals to produce a desired output frequency, the choice of Intermediate frequency and local oscillator is important. If poorly chosen, a spurious output can be generated. For example if 50 MHz is mixed with 94 MHz to produce an output on 144 MHz, the third harmonic of the 50 MHz may appear in the output. This problem is similar to the Image response problem which exists in receivers.

Looking at the possible answers above, A. a dummy load is not applicable as it takes the place of an antenna for tuning and servicing a transmitter. B. An Antenna switch merely switches antennas… and has nothing to do with harmonics. C. An SWR bridge measures reflected power, not harmonics, so D. A low pass filter remains.

A low-pass filter is a filter that passes signals with a frequency lower than a certain cutoff frequency and attenuates signals with frequencies higher than the cutoff frequency. The exact frequency response of the filter depends on the filter design. The filter is sometimes called a high-cut filter, or treble cut filter in audio applications. By attenuating (reducing) signals above the fundamental frequency we can effectively reduce harmonics.

The correct answer to our question therefore is D. Low pass filter.

~ John VE7TI




Friday, November 1, 2019

The November/December Communicator


Here is the Latest SARC Communicator

Projects, News, Views and Reviews... 


Here is the November/December SARC Communicator newsletter




This month 60 pages of projects, news, views, and reviews from the SW corner of Canada. 

Past articles and issues are available on our blog at https://ve7sar.blogspot.ca

We always welcome contributions of news, stories and your Amateur Radio experiences. The deadline for the next issue is December 15th.

73,

John VE7TI
Communicator Editor



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