• [FOAR] The power supply connector dance contest... (1/21)

    From FOAR via rec.radio.info Admin@21:1/5 to All on Mon Jul 18 13:48:30 2022
    XPost: aus.radio.amateur.misc, rec.radio.amateur.equipment, rec.radio.info

    Foundations of Amateur Radio

    The power supply connector dance contest...

    Posted: 09 Jul 2022 09:00 AM PDT http://podcasts.itmaze.com.au/foundations/20220710.foundations-of-amateur-radio.txt

    Foundations of Amateur Radio

    In over a decade of writing a weekly article about all manner of different aspects of our hobby and community, I've never once talked about power connectors for your radio. It's so universal as to be invisible and rarely discussed. So much so, that something you do out of habit, makes another
    stop dead in their tracks and ask themselves why they never thought of it.

    Despite how you might feel at the time, there's no such thing as a stupid question. The other day a fellow amateur Dave VK6KV asked about a power connector he'd seen at the local electronics store. That question started a group discussion about powering radios and how best to achieve that.

    The very first thing to discuss is that the vast majority of amateur radio transceivers expect a nominal voltage of 13.8 Volt DC. That might sound
    like a strange requirement, but it's the voltage that comes from a fully charged 12 Volt lead acid battery, which is what many radios use as a power reference.

    The next thing to consider is that a transceiver can draw quite a bit of
    power when it's transmitting. My Yaesu FT-857D user manual suggests 22
    Ampere, but I've never seen that in the decade it's been in my possession.

    When you purchase a radio, you'll likely discover that it either comes with bare wires, or some random connector that doesn't fit anything else. In
    many cases I've discovered that people cut off that connector and replace
    it with whatever standard they've come up with in their shack, but when
    they take their kit out on a field day, or acquire a new radio, the problem starts all over again.

    Let me suggest a different approach.

    The Anderson Power company, founded in 1877 by brothers Albert and Johan Anderson in Boston Massachusetts, make a range of connectors called the Anderson Powerpole and they come in a variety of ratings, sizes, shapes and colours.

    First introduced as a standard by the ARRL Emergency Communications Course
    in December of 2000, after previously being adopted by amateur operators in California, the Anderson Powerpole PP15/45 series was selected. The
    Coordinator for Hawaii State Civil Defense RACES, or Radio Amateur Civil Emergency Service, Ron, then AH6RH, now KH6D has a detailed description on
    his QSL page on how this came about.

    As a result, the stackable, asymmetric, genderless plugs are in wide use
    within the amateur community. The plugs are designed to be joined together using various orientations, creating a unique connector to suit your
    purpose. The Amateur Radio Emergency Service or ARES standard is one such orientation and before you adopt the Anderson Powerpole in your shack, make sure you use their orientation to avoid magic smoke from escaping your equipment.

    Picking a connector is just step one.

    When you acquire a new piece of 12 Volt equipment, you can cut off the connector and replace it with the ARES Anderson Powerpole connector orientation. Many amateurs I know then throw away the unusable connector,
    or shove it into a box for later.

    Instead, what I do is, terminate the plug that you just cut off in exactly
    the same way. Essentially, from a visual perspective, you've kept the power cable intact, but inserted a Powerpole join into the lead. As a result you
    now have a standard Powerpole power lead and you have a new Powerpole
    adaptor to suit the new connector.

    For that reason alone, I tend to bring a box of spare Red and Black
    Powerpole connectors to any field day and use the opportunity to spread the love around.

    As I said, the individual plugs come in a variety of colours, I have a selection of eleven in my shack, where for me a different colour means a different voltage or purpose. For example, I've adopted green as the colour
    for antenna radials.

    One challenge I'd not been able to resolve, until suggested by Ben VK6NCB,
    was how to avoid plugging a 12 Volt power supply into something that
    expects say 7.5 Volts. Colour alone isn't sufficiently idiot proof,
    especially in the dark. Ben suggested that I adjust the orientation of the plugs, preventing connectors of different colours to mate. Looking back, I can't understand why I didn't think of that in the decade I've been using

    I will note that there are other Anderson connectors in use. A popular one
    is the grey double connector, used in portable solar installations and caravans. I'd recommend that you consider if you really want to plug your
    radio directly into a solar panel or not and choose your connectors accordingly.

    Before you ask, to my knowledge the Anderson Power Company doesn't know I exist, nor did I get compensated in any way to say Anderson Powerpole. It's
    the ARRL Emergency Services standard and I'm happy to advocate for its use everywhere I go.

    So, whether you're using bare wires, banana plugs, Molex connectors or some other random barrel connectors, consider cutting the lead and inserting Anderson Powerpole connectors.

    When was the last time that you had to do the 12 Volt connector dance?

    I'm Onno VK6FLAB
    This posting includes a media file: http://podcasts.itmaze.com.au/foundations/20220710.foundations-of-amateur-radio.mp3

    Defining a standard on Contest Scoring

    Posted: 02 Jul 2022 09:00 AM PDT http://podcasts.itmaze.com.au/foundations/20220703.foundations-of-amateur-radio.txt

    Foundations of Amateur Radio

    Not a weekend goes by without an amateur radio contest or six, each with
    its own objectives, audience, times, rules, exchanges and scores. When you
    get bitten by the contesting bug, you'll quickly graduate from using pen
    and paper to keyboard and screen. That process comes with the inevitable selection of software suitable to both run on your shack computer and log
    your particular contest since as you'll discover, not all software knows
    about all contests or runs on every computer.

    When you eventually do arrive at a working solution, you'll reap the
    rewards of using technology. Contesting software can help in many different ways. From logging your operating frequency and mode to tracking where
    other stations are active and it doesn't stop there. Type in a partial
    callsign and your software can suggest which ones it might be. Log a
    contact and you'll see if your contact is valid within the rules or not. Software can track your activity level and warn if you're exceeding any
    contest time limits. It can keep track of multipliers and the impact on
    your total score and at the end of a contest, contesting software can help
    with submitting your log.

    After you've done this for a while, you'll notice that contest rules and scoring change over time. That brings with it the possibility of your
    software using old and invalid rules for validation, scoring and other contesting requirements.

    In most cases, software is updated manually by the author to implement the latest rules. This means that authors are required to keep up to date with
    the rules for all of the contests that their software supports, let alone
    add new contests.

    There are a few applications that support the idea of a contest definition which suggests the ability for anyone to define contesting rules to use
    them within the application. Unfortunately their functionality is strictly limited and they are not sufficient to define every contest rule that is in
    use today. Sadly, flexible as they might seem, they're neither universal
    nor compatible with each other. One definition, written by one amateur, for
    one application, cannot be used anywhere else, never mind trying to
    determine what the latest version is.

    I strongly believe that we need a shared open standard that can serve
    contest organisers, contest software developers and contest participants. Before I elaborate, I will be explicit in pointing out that the intent is
    to standardise in a way that makes it possible to document all past,
    current and future contests and in doing so, provide a collaborative way to share contesting rules between organisers, software developers and
    contesters, not to mention awards committees and amateur associations.

    So, if such a contest rule standard were to exist, what would it look like?

    Until now, the approach has been to create a list of keywords and values
    that deal with particular types of rules, things like band start and stop,
    zone score, valid prefixes, power level, exchange, etc. The result is a
    growing but always incomplete list of keywords with no means to define any logic. At the moment, all the contesting applications manage any scoring
    logic internally, requiring that it's updated when any of the rules change.
    Not only that, the contest organiser has no insight into the mechanism and
    no means to validate the process.

    As a contest organiser, scoring hundreds if not thousands of logs is a
    whole different challenge. Many contests do this manually, rely on someone else's software, or if the contest is popular enough, write their own code
    to manage the process.

    All this effort creates a disconnect between the contester, the organiser
    and the contest software developers, each using their own definition of the rules of any particular contest.

    A different approach might be to implement specific rules in a universal programming language like say JavaScript, and use those to manage the
    scoring and validation logic specific to each contest.

    For example, you might define a function that returns the starting and
    ending time for a contest which gives you a mechanism to detect if the
    contest is happening right now. A contester could use it to determine when
    the contest starts and ends, but the same definition could be used by the organiser to determine if a submitted log entry is for a valid time.

    Another might be a function that uses a callsign to determine if it
    attracts points or not and if it does, how many. Contesting software might
    use it to change the colour of the screen to indicate an invalid entry, but
    an organiser might use it to exclude a contact from a log.

    You could have a function to determine if the exchange is valid, or what
    the next exchange number is, or if the frequency on which the radio is currently tuned to is allowed for a contest.

    You could combine some of these simple rules to determine, for example, if
    the frequency the radio is on is the same or different since the last
    contact and if that's permitted or not within the rules.

    As long as the framework in which this standard is defined is extensible,
    any contest could be defined in this way.

    If it's written well, contest organisers might be able to write their own
    rules using this standard and everyone can use the same rules for their own needs.

    You might recall that I've spoken about aspects of this problem before and
    at the time I suggested that an amateur radio standards body would be
    helpful. Failing that there's nothing stopping a few people collaborating
    in a discussion about how this might be implemented.

    As an IT professional outside my shack I have some ideas on what's needed
    and what could give the whole amateur community something useful, but unsurprisingly, I don't know everything. Working together as contesters we might come up with a better result. As a starting point, I've created a repository on GitHub called "amateur-contesting-standard" to start a conversation about this scheme and I would love to read your thoughts and
    see your ideas on how this might be achieved.

    If you'd like to get in touch, send an email to cq@vk6flab.com or find my callsign on Twitter and GitHub.

    I'm Onno VK6FLAB
    This posting includes a media file: http://podcasts.itmaze.com.au/foundations/20220703.foundations-of-amateur-radio.mp3

    If you had money, what would your amateur adventure look like?

    Posted: 25 Jun 2022 09:00 AM PDT http://podcasts.itmaze.com.au/foundations/20220626.foundations-of-amateur-radio.txt

    Foundations of Amateur Radio

    A couple of weeks ago a friend, Ben VK6NCB asked an interesting question in
    our weekly net. He wanted to know, if money wasn't a concern, what would
    your ideal shack look like? The answers varied widely from leaving
    everything as is and using the money to retire, through to purpose built
    fixed or mobile shacks, with world wide DXCC activation travel and
    everything in between.

    My own answer was a little different. I envisaged establishing an RF
    research laboratory and spending my life exploring and investigating the
    ins and outs of the fundamentals of our hobby. Building software defined
    radios and building tools to leverage their capabilities.

    As far-fetched as money not being a concern might sound, it's something
    that a group of radio amateurs had to grapple with in 2019 when their group came into some money. The result is a private foundation with the aim to support, promote, and enhance amateur radio digital communications and
    broader communication.

    The foundation, Amateur Radio Digital Communications or ARDC uses its
    resources to provide grants to the amateur community. There's a number of criteria to be eligible to receive an ARDC grant, but you must at least
    relate to the support and growth of amateur radio, education, research and development. Grants are evaluated on a range of aspirational goals, things
    like reach, inclusiveness, innovation, social good and others.

    One of the first questions you might ask is how did these people get the
    money and why are they giving it away?

    To answer that we'll need to travel back to 1981 when Hank, KA6M had the foresight to imagine that Internet-style networking was going to be a thing
    and requested a block of IP addresses for use by radio amateurs. If you're
    not familiar, an IP address is like a telephone number, but for a computer. Hank was granted a block of 16.7 million addresses. For decades these were informally administered by a group of volunteers working under the name of AMPRnet and later 44Net.

    In 2011 the group founded ARDC as a California non-profit and officially
    took ownership of the network space and its management.

    At this point I'll make a slight detour into IP addresses. I promise it's relevant.

    For information to travel to a computer on the Internet it needs to have an address. That address, originally specified using a 32-bit number, a
    so-called IPv4 address, made it possible to uniquely identify around 4
    billion computers. With the explosive growth of computing and the Internet,
    the world started running out of addresses and in 1998, IPv6 was proposed
    to solve the problem. It uses a 128-bit number and has space to uniquely identify something like 340 trillion computers.

    In 2018, the ARDC was presented with a unique opportunity to sell some of
    its increasingly valuable address space, due to IPv4 address scarcity, but
    soon to be worthless, due to IPv6 adoption. After a year of internal discussion, in the middle of 2019, the decision was finalised and the ARDC
    sold a quarter of the address block that Hank had been granted back in
    1981. On the 18th of July, 2019, Amazon Web Services became the proud new
    owner of just over 4 million new IP addresses.

    I should point out that radio amateurs haven't ever used more than half of
    the original block and IPv6 is going to make this no longer any issue.

    So, how much did they make from this adventure?

    Well, each address sold for about $25, making for a lump sum of well over
    $100 million dollars which the ARDC used to establish its grants program.
    To round off the story, in 2020, the ARDC changed from a public charity to
    a private foundation and continues to administer the 44Net and the grants program.

    Their grants list is impressive and inspirational, so check it out on the ampr.org website. While you're there, you can subscribe to the newsletter
    and read about some of the amazing work that's flowing from the ARDC as a result of its efforts.

    At this point you might be getting all excited about applying for a grant
    and you should, but I'd like to ask a different question.

    What have you done lately to grow our hobby, to stimulate it, to encourage
    new people, to innovate, research and learn? What has been your

    So, if you had money, what would you do with your amateur adventure?

    I'm Onno VK6FLAB
    This posting includes a media file: http://podcasts.itmaze.com.au/foundations/20220626.foundations-of-amateur-radio.mp3

    How to isolate and by how much?

    Posted: 18 Jun 2022 09:00 AM PDT http://podcasts.itmaze.com.au/foundations/20220619.foundations-of-amateur-radio.txt

    Foundations of Amateur Radio

    If you connect the antenna ports of two radios together and transmit from
    one into the other, that would be bad, right? Just how bad would it be and
    what could you do differently?

    Before I dig in, you might ask yourself why on Earth this question even

    Consider having two radios and one antenna. You couldn't use a T-piece to connect two radios to the antenna unless both were receivers. So, after connecting and disconnecting coax for a decade, you might decide to use a
    two position coaxial switch instead. Set the switch to one port and the
    first radio is connected to the antenna, flick it to the other port and
    you've just avoided swapping coax between radios.

    I'll point out that in most cases a coaxial switch can be used to connect multiple antennas to one radio, or in reverse, connect multiple radios to
    one antenna.

    When you do start looking for a switch it would be good to test that at no point it connected any two switching ports together, potentially causing
    the magic smoke to escape from your radio.

    A less obvious issue is that a coaxial switch has a property called
    isolation. It's a measure of what part of a signal leaks between ports and you'll see the isolation or cross-talk of a switch described in decibels or

    If you recall, a dB is a relative measure. It means that it's something in comparison with something else, in our case, the amount of signal going
    into one port compared with the amount of signal leaking through to a disconnected port.

    You'd think that in a perfect switch none of the signal would leak through,
    but it turns out that under different frequencies a switch responds differently, even one specifically designed for switching radio
    frequencies. It might be that a 1 kHz signal is completely isolated, but a
    1 GHz signal is not, which is why when you look at the specifications of a
    coax switch, you'll see something like "greater than 70 dB isolation at 200 MHz". It's worth noting that the lower the frequency, the higher the
    isolation, indicating that in the worst case, at 200 MHz, there's 70 dB isolation, but at lower frequencies it has higher isolation, sometimes much higher.

    If you were to transmit into this switch with 5 Watts at 200 MHz, the
    amount of signal that can leak through would be 70 dB less than 5 Watts.

    You might recall that you can convert Watts to dBm to allow you to do some interesting calculations. As with other dB scales, it's in comparison to something else, in this case a dBm is in reference to 1 milliwatt and 5
    Watts is the equivalent of 37 dBm. This means that if you had a switch with
    70 dB isolation, you'd start with a 37 dBm transmission, take 70 dB
    isolation and end up with a -33 dBm signal leaking through. That's the same
    as 0.0005 milliwatts. In other words your 5 Watt transmission leaks through your coax switch to the tune of 0.0005 milliwatts.

    Is that enough to damage your radio?

    Well, that depends on the radio, but let's put some numbers against it.

    S9 on VHF and UHF was defined in 1981 as -93 dBm assuming a 50 Ohm
    impedance of your radio.

    So, our leaking signal, -33 dBm, is 60 dB higher than S9. You'd report it
    as a 60 over 9 contact, a tad excessive, but not unheard of. So by that
    metric, you should be fine.

    Many, but not all, radios specify the maximum radio frequency or RF power
    that they can handle. For example, according to the documentation, both the NanoVNA and a Icom IC-706 can each handle a 20 dBm or 200 milliwatt signal without doing damage. That means that your -33 dBm signal should't do any damage to those two devices.

    I'm off to see what the isolation is for cheap 12V relays to see if I can construct a cost effective, modular, remote control antenna switch with lightning detection.

    What are you building next?

    I'm Onno VK6FLAB
    This posting includes a media file: http://podcasts.itmaze.com.au/foundations/20220619.foundations-of-amateur-radio.mp3

    Smith, the chart to end all charts ...

    Posted: 11 Jun 2022 09:00 AM PDT http://podcasts.itmaze.com.au/foundations/20220612.foundations-of-amateur-radio.txt

    Foundations of Amateur Radio

    In the time that I've been a radio amateur not a day has gone by without learning something new. Today was no different and this time learning took
    me both by surprise and delight. I realise that being delighted by charts, since that's what we're talking about, might not be something that comes naturally, but I can highly recommend that you use this as an opportunity
    to explore.

    So, which specific chart am I referring to?

    The venerable Smith Chart, something which I've seen from a distance many
    times in the past decade, but never actually understood, or to be honest,
    even looked at with anything more than a glance and a shudder.

    My first exploration started with a book published in 1969 by the person
    who developed the chart, Phillip Hagar Smith, an electronics engineer. The book, over 250 pages, is dense and frankly my reading of the first part of
    the book did not fill me with delight, but based on what I discovered afterwards, I might revisit it.

    The purpose of the Smith chart is to visualise complex mathematical relationships. Instead of filling your worksheet with a litany of
    calculations, you can draw lines, circles and read the answer straight off
    the chart.

    For example, given the impedance of an antenna system, determining the
    standing wave ratio becomes a case of putting a dot on a chart, drawing a circle through the dot and reading the VSWR straight off the chart.

    It gets better.

    If you have a digital Smith chart, like the one shown on a NanoVNA or a RigExpert antenna analyser, you can read the antenna impedance in relation
    to frequency, use a tuner to change it and see the chart update in
    real-time in direct response to you changing inductance or capacitance by twiddling the knobs on the tuner.

    One of the main things that a Smith chart solves is to visualise a chart
    with infinity on it, twice. In radio a short-circuit is one extreme and an open-circuit is another. Coming up with a way to show both those conditions
    on the same chart is a stroke of genius.

    The chart has evolved over time, but in essence it's a circle with an
    amazing set of arcs drawn throughout. The very centre of the chart has the number 1.0 next to it. That's the point at which the VSWR is 1:1, the
    reactance is zero and it's called the prime centre. A dummy load should
    show up as a dot in that spot, regardless of frequency.

    The Smith chart is normalised. It doesn't matter if you're using a 50 Ohm
    or a 75 Ohm antenna network system, the middle of the chart is 1.0. Follow
    the horizontal axis to the right and you'll discover 2.0, that represents
    twice the resistance. If you're using a 50 Ohm system, 2.0 represents twice that, or 100 Ohm. Go to the left, find 0.5 and that represents half, or 25
    Ohm. The far left point on the horizontal axis represents zero Ohm, or a
    short circuit, the far right represents infinite resistance, or an open circuit.

    Positive reactance, or inductance is shown above the horizontal line,
    negative reactance, or capacitance is shown below the line.

    Going back to the middle of the chart, you'll discover a circle. All along
    that circle the resistance is the same, that is, on a 50 Ohm system, all of that circle represents 50 Ohm. If you look directly above the prime centre, you'll discover another 1.0 on the edge of the chart. The arc coming from
    that point represents an inductive reactance of 50 Ohm all along its path. Similarly, at the bottom of the chart you'll see an arc coming from a 1.0, representing the capacitive reactance.

    Before you pack it in with all this inductive and capacitive reactance,
    think of it as another attribute of your 50 Ohm antenna system. You don't
    need to precisely know how it works in order to use it.

    Remember how I mentioned that you could just read off the VSWR from the

    Drop a point on the chart, anywhere is fine. You can read off both the resistance and reactance following the two arcs through that point. If you
    draw a circle through the same point with the centre at the middle of the chart, the VSWR of that system is the number that you can read, where your circle crosses the horizontal axis.

    Before I go, there are plenty of YouTube videos on the topic, but there are
    a few that I'd recommend you explore. Among an amazing array of RF
    educational videos, Rhode and Schwartz made a ten minute presentation
    called "Understanding the Smith Chart" which walks you through how to read
    the chart and you don't need the prerequisites to follow along. In Part two
    of his "Smith Chart Basics" series, Carl Oliver shows how to look up the
    VSWR in three easy steps and Alan W2AEW has several videos showing the
    chart in action with several vector network analysers or VNAs and I'd
    recommend that you look at videos 264 and 314 to get started, but there's plenty more of his handy work to explore.

    If you take away anything from this, it should be that the Smith Chart
    isn't scary, there's just lots of stuff there, but spend a few minutes
    looking at it and you'll discover just how useful it can be in your day to
    day amateur antenna tuning adventures.

    If you've come across other interesting resources on the topic, don't
    hesitate to get in touch.

    I'm Onno VK6FLAB
    This posting includes a media file: http://podcasts.itmaze.com.au/foundations/20220612.foundations-of-amateur-radio.mp3

    Can you build an all HF band concurrent WSPR transmitter?

    Posted: 04 Jun 2022 09:00 AM PDT http://podcasts.itmaze.com.au/foundations/20220605.foundations-of-amateur-radio.txt

    Foundations of Amateur Radio

    It is in my nature to ask questions. It's been hammered into me from an
    early age and it often brings me new friends, new ideas and new projects.
    After spending quite some time mulling over my understanding of radio, I
    came up with this question: "Is it possible to build a single radio
    transmitter that is capable of emitting a WSPR signal at the same time on
    all the HF bands?"

    Before we look at the hardware, let's contemplate for a moment what this transmission might look like.

    Imagine a WSPR transmission as a normal audio signal. It sounds like a
    couple of warbling tones for two minutes. Unpacking it, the audio signal is about 6 Hz wide and sits somewhere between 1400 and 1600 Hz. If you were to draw a power chart of this, displaying the frequencies horizontally and
    power vertically, you'd see a completely flat chart with a little spike, 6
    Hz wide, somewhere between 1400 and 1600 Hz.

    Using an analogue radio, you can play this sound into the microphone or
    audio port and the radio takes care of transmitting it on the 10m band as a
    28 MHz beacon. Tune the radio to 40m and it appears as a 7 MHz transmission.

    The two takeaways are that the WSPR signal itself doesn't change between
    bands or transmissions and the radio does the heavy lifting to make your
    WSPR transmission come out at the right frequency.

    Your radio is moving the audio frequencies to the correct amateur band. The electronics in your radio achieve this move by mixing the audio and the
    tuning frequencies together.

    If you imagine a 28 MHz WSPR signal coming from your transmitter as a power chart, it's essentially silence, except for a little WSPR peak somewhere
    just off to the right of 28 MHz.

    From a mathematical perspective, the frequency mixer in your radio is performing a multiplication and best of all, you don't need a radio to do
    this. You could use software to multiply frequencies instead and end up
    with something that represented their product. If you were to create a
    power chart of this equivalent multiplication, you'd see a completely flat chart with a little spike near 28.1261 MHz.

    Sound familiar?

    It gets better.

    You can store the result of this calculation in a file as a 28 MHz WSPR
    signal and you could do this as many times as you want. You could create a
    file with a 3.5 MHz WSPR signal, one with a 7 MHz one and so-on.

    Since we're talking about shuffling numbers only, you could combine all
    these calculations, and end up with a single file that had several WSPR
    signals inside it.

    The chart picture is again mostly silence, just with little WSPR peaks at frequencies suitable for say transmission on the 80, 40, 15 and 10m bands.

    Now all you need is to find a device that's capable of transmitting it.

    Turns out that we have such a device. A PlutoSDR, a software defined radio which I've spoken about before. It's capable of transmitting a 56 MHz wide signal, more than ample for what we're doing. We don't need to use the
    PlutoSDR to calculate the combined signal either, since we can do all that
    in advance, because as I said, a WSPR signal doesn't change.

    So essentially, all we'd need to do is generate a file that has all the
    WSPR signal information at the right frequencies and send it to the
    PlutoSDR to transmit.

    There are a couple of hurdles to overcome.

    When you multiply two frequencies, you end up with two peaks, one at the
    sum of both frequencies, and one at the difference between them. One you
    need, the other you don't, so we're going to need to filter this out,
    something that your analogue radio circuit also does.

    Another challenge is around sampling rates. The PlutoSDR needs a specific sampling rate and bit depth, so we're going to have to generate our file
    just so. I'm going to skip past complex numbers and move on to power
    output, since all the power from the transmitter will be spread across all
    of the combined WSPR signals we're attempting to transmit, so we're likely going to need amplification.

    There's also the matter of testing before we actually connect this
    contraption to an antenna and I've glossed over one minor but essential
    point, the PlutoSDR doesn't do HF.

    So, where does this leave us?

    We can build a proof of concept using 2m and 70cm. Both those bands are
    native to the PlutoSDR. I'm currently working on generating the actual WSPR signal file to start the transformation process. A friend has some testing
    gear that could allow us to see what's coming out of the transmitter
    without polluting the airwaves and of course, at this point this is all
    still "What-if". I've not actually made this work, but it's keeping me entertained and that's half the fun.

    It gets even better. The Pluto has an FPGA on board, so theoretically at
    least, we might be able to generate this actual file inside the Pluto in real-time, which opens up a whole other avenue of exploration, but we'll
    start with crawling before running.

    If you have thoughts on this, or any other aspect of the hobby, please get
    in touch. You can send email to cq@vk6flab.com or you can find me on
    Twitter and Reddit with my callsign.

    In the meantime, you know the drill. Get on air and make some noise.

    I'm Onno VK6FLAB
    This posting includes a media file: http://podcasts.itmaze.com.au/foundations/20220605.foundations-of-amateur-radio.mp3

    What are the rules for calling CQ on a repeater?

    [continued in next message]

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