• [FOAR] The power supply connector dance contest... (19/21)

    From FOAR via rec.radio.info Admin@21:1/5 to All on Mon Jul 18 13:48:30 2022
    [continued from previous message]

    fully functional gadgets like smart phones, the idea of going back to radio might seem like a step backwards, but I'd like to point out that we're
    radio amateurs. That's like being a chef and ordering take-out when you
    have a fully stocked kitchen.

    If you're experienced in this hobby you'll know that nobody needs to grant
    you permission to host a net, but if you're new here you might not. So, to
    you I say: "You don't need permission to host a net, so get to it."

    There are some things I've learnt since starting F-troop nearly a decade
    ago. Start small. Depending on the skill-level of the participants, choose
    an option for hosting it. F-troop is run with a single net-controller,
    often that's me, and the role of net-control directs who's next to talk. If you're just playing around, the tried and true version is a round-robin
    net. You'll need to pay attention a little better because you'll need to
    know who comes after you so you can hand the call to them. There are also variations on this, but again, start small.

    I track contacts in a spreadsheet, but a piece of paper is just fine.
    Writing down all the stations you hear is a great idea, since it helps you
    keep track of who's said what. You can add information as it comes to hand.
    If the net is on HF you might record the signal strength you see when
    you're listening to each station, as well as the name and location or QTH.

    Pro-Tip, use a new piece of paper for each net and put a date on it. Future
    you will love you for it.

    My point is that there should be absolutely no impediment to getting on
    air, making noise and breaking isolation from the comfort of your own shack.

    I'm Onno VK6FLAB
    This posting includes a media file: http://podcasts.itmaze.com.au/foundations/20200405.foundations-of-amateur-radio.mp3

    Listening from the ground up

    Posted: 28 Mar 2020 09:00 AM PDT

    Foundations of Amateur Radio

    When I started learning about antennas I was told height is might. The
    higher the better. For many years I've followed that advice and like a good little parrot I've dispensed that advice. Turns out that as is usual in our hobby, that's not the whole story.

    I first came across a ground based antenna with a BOG, that's a Beverage On Ground antenna. It's essentially a long length of coax that's pointed at
    what you want to hear. You can either terminate the end, or not, different effects result with plenty of discussion about directivity, angles, lobes
    and the like.

    One of the things you'll notice with you use a Beverage antenna is that
    it's quiet. All signals are reduced in strength, but that also means that
    noise is reduced. Turns out that this pays off and you hear stuff that
    you've not heard before. Excellent for a field day or if you want to hear
    some serious DX stations.

    There's plenty of stuff that's not nice about a Beverage antenna. For one,
    it's highly directional, it takes up lots of space and if you want to
    listen in another direction, you'll either build a second or third and
    switch between them. That, or you'll be rolling up and laying out the coax
    to point at a new DX entity.

    You also cannot transmit with a Beverage antenna. While we're on the
    subject, often a beverage can be combined with a vertical, one for receive,
    the other for transmit. It's one of the projects that lying in my to-do
    pile. I've even got a remote controlled coax switch, but I'm still figuring
    out how to make my FT-857d do the switching.

    I could stop there, but I came across another idea a couple of weeks ago.
    At the time I was being introduced to the local emergency communications
    team. They showed me their HF stand-by gear. Long piece of wire that you
    could chuck out on the ground and make contact. As a good little amateur I remember thinking to myself, these poor people they have a lot to learn.
    I'm glad I'm an eager apprentice in learning the art of keeping my big
    mouth shut.

    During F-troop, a weekly net for new and returning amateurs, you'll find details on vk6flab.com, another amateur was talking about putting a wire
    near the ground, like about a foot off the turf with great results.

    I tried it on the weekend with a friend. We were out camping for a local amateur contest, miles from anywhere and anyone and I recalled the
    emergency communications people and the story during F-troop. We had some
    time to play, so we started with a long-wire, actually, pretty-much a wire dipole on the ground. Plugged it in, turned on the radio, magic. Same kind
    of sound effect as a Beverage antenna. Nice and quiet, good signals to be heard. We turned the whole contraption 90 degrees, no difference. Since
    then I've learned that it's pretty much omni directional and unlike a
    Beverage antenna, you can use it to transmit.

    Of course it's not going to act in quite the same way as a dipole high in
    the air, and that's pretty obvious, since it's not in the air. It'll give
    you communications that are called NVIS, or Near Vertical Incident Skywave, essentially stuff that goes straight up and comes down, stations up to
    about 400 km or so away. For scale, that's enough to cover all of Holland.
    In Australia it's enough to cover the state of Victoria, or the width of
    the UK, and most of the width of the State of New York.

    Before you get all huffy and point out that this is not a great DX antenna
    I'll beat you to it and tell you that this is not a great DX antenna. It's
    not meant to be. Nor is it intended to be an instruction on what antenna to build next. This is purely intended to illustrate that antennas come in all manner of shapes and sizes and there is lots to be learnt from trial and

    I know that this is a "compromise" antenna. Guess what, so is every other antenna. Today the compromise is that we don't need any poles, trees or unsuspecting human support structures to keep an antenna in the air. You
    can essentially try this one for free at any time, on your own, on the
    beach, in a park or on the side of a mountain.

    Another great use is to talk to your friends who live in the same city on
    HF. I have no doubt you could even manage some FT8 contacts using this

    Next time someone tells you to put your antenna in the air, ask them who
    they want to talk to. If it's locals, then there is absolutely no need at
    all. As for mastering the art of keeping my big mouth shut, we'll see.

    I'll leave you with this. It's not the answer that's important, it's the question, for everything else there's experimentation.

    I'm Onno VK6FLAB
    This posting includes a media file: http://podcasts.itmaze.com.au/foundations/20200329.foundations-of-amateur-radio.mp3

    What level of preparedness are you at?

    Posted: 21 Mar 2020 09:00 AM PDT

    Foundations of Amateur Radio

    An often repeated statement about the purpose of our hobby is related to emergency preparedness. The various peak bodies around the world devote
    plenty of resources to the concept, with helpful examples, umbrella organisations, training, coordinators, grants and funding,
    photo-opportunities and all the other trimmings that come from the idea
    that you and I are going to be of assistance in the case of some or other emergency.

    Looking up the various emergency coordination groups is a disappointing experience. From broken web-sites with non-existent pages to latest news
    that's over two years old, through to the latest sausage sizzle and
    fun-run. Entreaties to make sure that you have your current Membership ID
    card, otherwise you won't be covered for insurance purposes. As I said, all
    the trimmings with lots of evidence of paper pushing and little or no
    evidence of actual preparedness, let alone public information that might
    help any new or old radio amateur become prepared.

    Back to the topic at hand and leaving aside the nature of the emergency for
    a moment, given that the response for a bush-fire, a cyclone, flood or pestilence is likely to be different.

    Let's look at the things we have direct control over.

    If you have at any time taken your radio out of the shack and carried it
    into a paddock, connected it to an antenna, fired it up and made a contact, you're well ahead of the curve.

    There are plenty of amateurs who have never ever considered what going field-portable might look like, let alone tried it. That's fine if you live
    in a bunker, have independent power and are able to withstand all manner of disaster scenarios, but realistically it likely means that your emergency assistance will be of the kind that's outside the emergency zone. Helpful
    to be sure, but there's plenty of those stations to be found - unless the
    issue is global, in which case we have a completely different set of
    problems, pandemic, anyone, anyone?

    Let's focus on the other side of the fence.

    You're in an emergency zone. Doesn't matter what kind of emergency. Communications are limited or overwhelmed, information is restricted,
    messaging is hampered and you're a radio amateur with a working radio. If
    all goes well you should be able to help.

    So what does a working radio look like and what does helping mean?

    First thing to think of is power. Have you got a battery? Is it charged?
    When was the last time you tested it? How long has it been sitting on the shelf? Did it discharge in the meantime? What about a charger? Have you got
    a generator? What about fuel and oil? What about spare parts? Have you got something else, like a solar panel, a wind generator or a water turbine?
    What about a push-bike with a dynamo attached? How long does your radio run
    on a battery and at which transmitter power level is that?

    After thoroughly investigating power, what does your actual emergency
    station look like? Will it be used for voice communication, or will it be
    used as a digital gateway? Can you use it to send rudimentary messages, or
    can it be used as an internet gateway for a local community?

    What bands are you planning to operate on? Do you have an antenna? What
    happens if your current antenna is taken out by a fire, lighting strike or something else? When was it last tested? Do you have a back-up antenna?
    Have you actually used this antenna? Does it have all the right connectors
    and are they with the antenna?

    So, pretend that you got all that right. What about you? Have you got spare clothes? Food? Shelter? Medication? What about Personal Protective
    Equipment, masks, gloves, what-ever? What about ancillary items like pen
    and paper? Do you have power for the laptop that's being used to create the digital mode messages?

    Note that I've not said a word about the usefulness of any of this. This is
    the base level of preparedness just so you can actually look yourself in
    the mirror and say that you have at least got a level of ability to be of assistance in the case of an emergency.

    You can of course argue that you should hook up with the local emergency services and offer your skills as a radio amateur. That's helpful, but what
    if you cannot actually go to the muster point? How does that help?

    Now lets pretend that you actually have done all this. When was the last
    time you tested it?

    What does the actual helping look like?

    Have you ever attempted to pass emergency messages? What about messages
    that must be transferred absolutely 100% correctly, think medication
    dosages? Who did you pass them to? When was the last time you did a
    regional emergency simulation between your amateur friends? How often do
    you do this? Once a decade, or more often than that? What if the local
    repeater isn't working? What about in your club or your local
    neighbourhood? Do your neighbours even know you exist?

    The point of all of this is to reveal that the level of emergency
    preparedness for radio amateurs is in my opinion spotty at best. If you disagree with me because you are prepared I'd like to ask if you helped
    prepare your local amateur community and the wider community around it? I
    don't doubt that there are individuals, even groups who are prepared, but I suspect that they are far and few between.

    When was the last time you actually went into the field for a week and
    played radio, for real, battery only, limited resources, no outside help?

    I'd love to believe that this is universal, but you and I both know that
    there is plenty more to be done. How realistic is your emergency
    preparedness and what are you going to do about it?

    I'm Onno VK6FLAB
    This posting includes a media file: http://podcasts.itmaze.com.au/foundations/20200322.foundations-of-amateur-radio.mp3

    On the shoulders of giants we stand.

    Posted: 14 Mar 2020 09:00 AM PDT

    Foundations of Amateur Radio

    One of the things I love most about this hobby is the ability to randomly
    dart off into any related direction and learn new stuff. For example, the
    names Nikola, Guglielmo, Heinrich and Edwin emblazoned on a t-shirt sent to
    me by a very appreciative listener Jack KI4KEP, started an exploration into
    the deeds and misdeeds of the people behind those names.

    The first three might be somewhat familiar, Nikola Tesla whom we have to
    thank for inventions like Alternating Current, the Tesla coil, wireless
    power, radio remote control and many others. The Tesla company is named as
    a tribute to him. The magnetic flux density uses the letter T as its symbol
    and its called the Tesla.

    As a side note, if you've ever struggled to decide if a symbol needs to be
    a capital letter or not, like say the V for volt, the A for ampere, the O
    for ohm, the m for meter, the s in second or the K in kelvin, you just need
    to remember that if the unit is named after a person, the symbol needs to
    be a capital letter. That does assume that you know that the unit is named after an actual person, like say the Earl of Sandwich.

    Name two in our list, Guglielmo Marconi is the person whom we can thank for
    the practical development of radio communication, using improved spark-gap transmitters, the development and commercialisation of long-distance radio transmissions and his association with many other services such as a transatlantic radio-telegraph service, providing communications to shipping such as Jack Phillips and Harold Bride who were employed by the Marconi International Marine Communication Company to act as radio operators on the
    RMS Titanic on its fateful voyage.

    Our third name, Heinrich comes into sharp focus when I add his surname,
    Hertz. His name continues on in our day-to-day language and Heinrich Hertz
    is responsible for validating many of the underlying principles of our
    hobby. Using a spark-gap transmitter he was the first to conclusively prove
    the existence of electromagnetic waves which were predicted by James Clerk Maxwell. He also came up with the parabolic antenna, the dipole antenna, measurement of electric field intensity, electromagnetic waves and many
    other experiments. If you've ever seen a bullet hole in glass, you've seen
    a Hertzian cone.

    The last name had me stumped. It took a question to learn that Edwin shares
    a name with a famous cyclist and a famous astronaut, namely Armstrong.
    Edwin Howard Armstrong has been called "the most prolific and influential inventor in radio history".

    If you're like me you may not have heard of Edwin Armstrong. You might be surprised to learn that he's responsible for the regenerative circuit, the super-heterodyne circuit and while he was working on defending his
    invention against a claim made by a patent attorney he stumbled on the super-regeneration circuit. If you're a radio amateur, you'll likely have
    heard those terms, if not, they're electronic circuits that make radio receivers more sensitive which forms the basis of many radios in use today.
    My Yaesu FT-857d is a super-heterodyne radio for example.

    It doesn't stop there. The biggest claim to fame that Edwin Armstrong
    brings to the table is the invention of FM radio. It took many years and a protracted lawsuit that lasted until almost a year after he died to finally have Armstrong formally established as the inventor of FM.

    Not for a minute will I suggest that my exploration was comprehensive or in-depth, but it made my day when I put on a t-shirt with the names of
    those inventors who made it possible for me to be here and share this with
    you today.

    On the shoulders of giants wearing a t-shirt with their names I stand.

    I'm Onno VK6FLAB
    This posting includes a media file: http://podcasts.itmaze.com.au/foundations/20200315.foundations-of-amateur-radio.mp3

    All bands + All modes + All countries

    Posted: 07 Mar 2020 08:00 AM PST

    Foundations of Amateur Radio

    A regular lament is the lack of things to do in our hobby. I know, it's
    foreign to me, but there are plenty of amateurs who express frustration at
    the lack of activity, no contacts, nothing new, no challenges.

    For my poison, I started the process of contacting 100 different countries using 5 Watts. I've been at it for a number of years and truth be told,
    since my latest domestic move, over two years ago now, my efforts have been
    put on hold. Not because I didn't want to, but because I was getting
    annoyed with having to leave my home and wanting desperately to have a functional shack at home. As you might know, that's a project that's still
    in hand and thanks to some magnificent assistance from various places, I'm still making progress.

    That said, your perspective might be dulled by the notion that this pretty
    much concludes the on-air activity possibilities that exist. Within my own license class, until recently, I was permitted to use voice modes like SSB,
    AM and FM and I was permitted to use hand-keyed Morse. I have access to 10 Watts and am currently allowed to use six different amateur bands, namely
    80m, 40m, 15m, 10m, 2m and 70cm. So together with the four modes, I'd be
    able to make 24 different contacts to 100 different countries, that's 2400 different combinations.

    Of course there are more than 100 countries, that is, DXCC entities. The
    2018 list has 340 of them, so that's over 8-thousand different options for getting on air and making noise.

    Last year all that changed. The local regulator in Australia, the ACMA
    decreed that all amateurs in Australia were permitted to use all modes.

    It's taken a little while for that to sink in. Specifically what it means
    for me.

    A quick search reveals that there are at least 60 different digital modes, think RTTY, Olivia, PSK31, etc. In addition to those, there's a plethora of other modes like IRLP, AllStar Link, EchoLink, CODEC2 and Brandmeister.

    So conservatively I'm going to estimate that I now have got access to over
    a hundred different modes, across six bands with 340 countries, that's over 200-thousand different options for making a contact.

    Of course it's unlikely that I'll make a contact between say Belize V3A and Perth VK6 on 2m using Olivia, but even if we limit our calculation to HF,
    we still have at least 136-thousand opportunities for adding something interesting to your logbook.

    I've been hunting for a canonical list of all the various amateur modes and
    the tools needed to make and receive them. No doubt that will take me some time. I'll be documenting it on the projects page on vk6flab.com if you
    want to follow along. Speaking of which, you'll also find past episodes of
    this podcast there.

    I suppose I should start by converting my current efforts into some pretty pictures that show what I've been up to so far, but that's a mapping
    exercise that I'll have to add to my to-do list, since I'm guessing it
    involves learning how to use some fun mapping tools.

    If 136-thousand opportunities isn't enough, you can also add grid-squares, large and small, different prefectures in Japan, provinces in the
    Netherlands, CQ zones across the world or ITU areas, prefixes and operating modes.

    Clearly there's plenty to do and see.

    I wonder if there's an award for all modes all bands all countries and I
    wonder what happens if someone invents a new mode?

    I'm Onno VK6FLAB
    This posting includes a media file: http://podcasts.itmaze.com.au/foundations/20200308.foundations-of-amateur-radio.mp3

    The impersonal nature of digital and other myths

    Posted: 29 Feb 2020 08:00 AM PST

    Foundations of Amateur Radio

    The other day I bumped into a concept that I've heard repeated before. The so-called "impersonal nature" of digital modes.

    There's this idea that any communication that isn't using voice, is devoid
    of the human touch. Often this assertion is specifically made in relation
    to modern digital modes like JT65 and FT8. As an aside, I've never heard it
    in relation to other digital amateur modes like slow-scan television, RTTY
    or PSK31.

    In the early 1900's when amateur radio was beginning to be a thing, the
    means of communication was Morse Code. With beeps across the globe contacts were made between amateur stations. With every incoming dit and dah,
    letters were received, words constructed and meaning derived. This is long distance communication in its early stages.

    Each amateur was said to have a fist, their particular rhythm of touching
    the key. Across multiple stations it was possible for an experienced
    operator to distinguish between two amateurs based on how they were sending Morse Code. I can confirm that if you've ever had the privilege of hearing
    lots of amateurs clamour in a so-called pile-up, you can hear for yourself
    that different stations sound different, even if they're all sending Morse Code.

    So on the one hand we have this deeply inhuman means of communications like Morse Code which is by the language we use considered to be made by humans, personalised with a fist. On the other hand we have a deeply technical mode like FT8 which isn't.

    During the week I was discussing this change of perception during a
    haircut. I pointed out that this happens everywhere. For example, in the hairdressing profession an electric clipper might have been seen as
    impersonal when it was invented in 1921. Today it makes quick work of a
    Number 1 cut. In mobile phone communication an SMS was seen as impersonal
    with voice preferred, but today the world would look quite different
    without the 5 billion messaging mobile phone subscribers. In 2013 it was estimated that there were 8 trillion SMS messages, and 10 trillion other
    smart phone messages. As you might realise, behind each of those messages
    is a human, well, apart from the SPAM and the computer notifications, but
    even those are programmed by a human.

    So what makes the difference between Morse Code and FT8? Why is an SMS impersonal in 1992, but preferred by most today?

    I'd hazard a guess and state that the experience of the person making the statement has a lot to say about their perception of the nature of the

    My typing away at a keyboard and seeing words appear on my screen might not appeal to someone who chased a turkey around the yard in search of a quill,
    but then electricity might also be surprising.

    It's interesting to me that PSK31, something that's not particularly
    thought of as being impersonal, was introduced to the amateur radio
    community in December 1998 by Peter G3PLX. The first Weak Signal modes, commonly known as WSJT modes, were introduced in 2001 by Joe K1JT, only
    three years later. JT65 came around in 2003. We have this situation where
    PSK31 is not impersonal, but JT65, which is five years younger, is
    considered impersonal and the popular mode FT8, which is an extension of
    JT65 is said to be the end of the hobby.

    If hyperbole would relate to truth, the end of our hobby in sight, we
    should all get rid of our radios and hand back our licenses.

    Perhaps we should take a step back and notice that behind every FT8
    station, behind every voice-call, behind every amateur transmitter is at
    some point a human with a license. If we're splitting hairs, then a local automatic voice repeater must be the height of impersonal.

    The other thing I'd like to point out is that how you perceive the use of a particular mode is also important. If you think of FT8 as having a personal beacon in your shack that uses your radio and your antenna to measure how
    well your signal is heard across the globe, you might just start enjoying
    this so-called impersonal mode.

    One of my friends, Wally VK6YS, now silent key, told a story where he was driving down the highway to meet his friend. They were chatting away using Morse Code, Wally in his car, the friend in his shack. Once Wally arrived
    the friend wanted to see how Wally was able to send Morse Code whilst
    driving and could he please see his Morse key? Wally confessed to having whistled into his microphone to make the contact, since he didn't have a
    Morse key in his car. According to Wally, his friend was off the air for
    months in disgust.

    I should mention that my Number 1 haircut looks great, if only for the fact that it allowed me to spend some quality time discussing and contemplating
    the nature of the hobby that I love.

    I'm Onno VK6FLAB
    This posting includes a media file: http://podcasts.itmaze.com.au/foundations/20200301.foundations-of-amateur-radio.mp3

    The chicken and the egg, which comes first, the antenna or the radio?

    Posted: 22 Feb 2020 08:00 AM PST

    Foundations of Amateur Radio

    In my day to day activities as a radio amateur I come in contact with
    people across all parts of their amateur journey. Some who don't yet know
    that they're amateurs, through to those who've just passed their test and
    are waiting for their callsign. Then there are those who have been amateurs
    for a while, experimented a bit and have settled down into the comfort of
    being a member of an active community. Stretch that further and I also
    spend regular quality time with amateurs who have been licensed longer than I've been alive.

    Recently I received an email from a freshly minted amateur. Just like me,
    still pretty much wet behind the ears, keen as mustard, trying very hard to figure out what to do next and where to go.

    The basic gist of the email from this amateur was that they didn't know
    what kind of antenna they could erect at their home and failing that,
    couldn't decide on what radio to acquire to match the antenna that they
    hadn't decided on, not to mention that the antenna needed to match the
    radio that didn't yet exist.

    If you've been around this community for a while you might recognise the chicken and the egg, which comes first, the antenna or the radio?

    The answer is obvious, hidden in plain sight, easy to deduce, simple to understand, and completely useless.

    Let me help you with the answer: It depends.

    If that didn't test your patience, even if you've been an amateur for
    longer than my parents have been alive, you'll know that this is an unanswerable question.

    So how do you break the egg and get started?


    Start somewhere.

    As it happens I have a recommendation. It's cheap, simple and it will get
    your feet wet sooner rather than later. My recommendation is neither, or
    both, depending on your perspective. I promise, I'll get to the point
    shortly. The reason I'm making it last and savouring the point, some might
    say, belabouring it, is because it's one that happens over and over again,
    day in, day out, year in, year out.

    My recommendation is that you spend $25 on an RTL-SDR dongle and hunt
    around your home for a piece of wire. That's it.

    If you're not familiar with an RTL-SDR dongle, it's essentially a USB thumb-drive sized device that plugs into the nearest computer and paired
    with the correct software it has access to many if not all of the
    frequencies that you as an amateur are allowed to play with.

    Given that it's a receiver, the antenna doesn't really matter all that
    much, at least not initially, so any piece of conductive wire will suit.
    Most dongles even come with an antenna of sorts, so you can get started straight away.

    Resources associated with this podcast are on the vk6flab.com website where I've also collected a few links under F-troop to get you on your way with
    an RTL-SDR dongle.

    The purist radio amateurs will likely arc up at this point and mention that this isn't real amateur radio, to which I can only say: Bah Humbug. Radio
    is about receiving as much as it is about transmitting. Any fool with two
    bits of wire can transmit, but it takes finesse to receive, so start there.

    There are other benefits from going this way. Other than ease of entry,
    that's another way of saying - cheap - you can easily spot where and when
    there is activity. You can use all the traditional modes like CW, SSB, AM
    and FM, but you can also play with all of the new modes like WSPR, FT8,
    JT65 and investigate some of the other modes like RTTY, PSK31, Olivia, SSTV
    and others.

    All this will help you have a better idea of the landscape you're stepping
    into without a major purchase.

    To really set a cat among the pigeons, I'm also looking into a Raspberry Pi based transmitter, rpitx by Evariste F5OEO. When that bears fruit I'll let
    you know. In the mean time, play, learn, listen, experiment. No need to
    spend hundreds or thousands of dollars while you're still unsure.

    Even if you already have a lovely amateur station, an RTL-SDR dongle is
    worth every cent and then some.

    I'm Onno VK6FLAB
    This posting includes a media file: http://podcasts.itmaze.com.au/foundations/20200223.foundations-of-amateur-radio.mp3

    Exploring an understanding of filters and circuits.

    Posted: 15 Feb 2020 08:00 AM PST

    Foundations of Amateur Radio

    Every person is the product of their environment. Unsurprisingly this is
    even true for radio amateurs. That's not too say that we can't break our
    mould, but it takes effort. I grew up around technology in the 1980's. As a result I'm familiar with 8-bit microprocessors like the Motorola 6502 which featured heavily at the time. I tend to think in terms of the presence or absence of a signal, rather than the intricacies of circuits and components.

    As a child of my time, I'm not particularly familiar with the punch card or paper tape, or core memory, or valves, 386 machine code or what's in an
    FPGA. As a direct result of my age, my knowledge and understanding of
    circuits is sparse at best. I understand basic components like resisters
    and capacitors in a DC setting, Ohms Law and the fun you can have with a battery, a few resistors, diodes and an LED light.

    As a radio amateur I've been introduced to how some things work differently
    in an AC circuit, like an antenna and a feed-line.

    Until very recently my knowledge about filters was based on what I'd read.
    I know that there is fun to be had with coax and stubs and other cute
    things, but how and why they work eluded me. Today I'm a step closer.

    Before I dig in and share some of what I've learnt, let's have a quick look
    at what a filter is and does. You'll have likely heard of high-pass and low-pass filters. You might have heard of band-pass and band-stop filters.

    If you think of a high-pass filter as a device that lets through high frequencies and a low-pass filter as a device that lets through low frequencies, we're already well on our way. If you put a high-pass filter together with a low-pass filter, you end up with a range of frequencies
    that doesn't pass, known as a band-stop filter.

    Similarly, if you tweak the frequencies that pass just so, you can combine
    a high-pass and a low-pass filter to make a band-pass filter.

    Let me illustrate.

    Imagine a 15m band-pass filter. It allows all frequencies in the 15m
    amateur band through, but blocks everything else. You could construct such
    a thing from a high-pass filter that allows 15m and above through combined
    with a low-pass filter that allows 15m and below through. Everything below
    15m is stopped by the high-pass filter and everything above 15m is stopped

    [continued in next message]

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)