Jan 042022
 

At the heart of the “big loop” antenna is the SG-237. Click here to see the manual for that.

The tuner can be run without a controller, but it offers a few features with a controller that are useful (and sometimes important) in practice. I took a look at the controller suggested in the manual and re-designed it a bit to better suit my purposes. First, because I wanted to use parts that I had laying around the lab, and second because I wanted a better “light-show.”

The important features are:

  • You can tell the tuner when NOT to tune. I find in practice that this can be particularly important when running digital modes as switching things around at the antenna can inject unwanted noise to your transmitted signal.
  • The tuner can tell you when it’s found a good tuning solution. Sure, it seems like this would be obvious enough once the SWR stops bouncing around… but it is awfully handy to have a nice green light tell you when the tuner has stopped looking.
  • I found this out AFTER I built my controller – The tuner can tell you when it didn’t find a solution but has given up trying! On my tuner controller there is an amber light for when the tuner doesn’t yet have a solution and a green one for when it has found a solution. One day I saw these flashing back and forth like it was shaking its’ head. I figured out that’s what it does when it gives up trying. This doesn’t seem to be documented anywhere, but it’s also a nice feature.

The first step was to draw up a schematic for the circuit and do a little math to make sure everything would work.

In the controller recommended in the manual they roll their own ~9 v regulator using a zener diode and an NPN transistor. They only use this to drive their LEDs, so I did something similar but instead used an actual 5V regulator.

The next thing I changed was the “tuned” indicator logic. Their controller pulls one side of their tuned indicator to ground when the tuner is happy. I presume this is done through something like an open collector in the tuner.

I wanted two lights instead of one so I added a 2N2222 transistor and a resistor to turn on an amber “not-tuned” LED when the green “tuned” LED is not on. Basically, the green LED and its’ current limiting resistor act like a pull-up resistor to bias the transistor on whenever the “tuned” LED is not pulled to ground by the tuner. The 47K resistor in series with the base ensures that any current that flows is tiny enough that the green LED won’t light (at least not in a way you can see it). The gain of the transistor is high enough that it will still effectively saturate in this condition thus turning on the amber “not-tuned” LED.

The rest of the circuit is essentially the same as their controller – so the tuner sees almost precisely the same signals. This consists of a DPDT switch, a momentary SPST push-button, and a handful of decoupling caps. All of this, a handy box, and some LEDs with built-in current limiting resistors were all handy in my lab… courtesy of the recently (at the time) defunct local Radio Shack – and my irresistible urge to grab everything I could from them in their last days.

Once the design was done it was time to put the mechanical components into the box and see how they all fit. Here is where some on-the-fly creativity was required because one cannot always be sure what parts they have nor how they can be used to solve a particular problem… I mean, I wasn’t building this from a BOM where I could order up precisely what I wanted right?! I had to see what I had around and improvise with that.

As it turns out all of the parts I had handy fit perfectly including some PCB mounted screw terminals that I was able to adapt to the back of the box with a little bit of drilling, sanding, and some small pieces of protoboard.

Next up I designed the layout of the electronics on another piece of proto-board. It’s always a good idea to take this extra step rather than going directly to soldering parts in place – even on something simple like this. The end result almost always turns out better and cleaner for the extra effort.

Then, once I’d put all of the parts in place I made a few measurements (idiot test) to make sure I got it right. A quick look at the box also informed me that I was going to need to make a notch somewhere on the board so that the wires from red LED could get to the other side. The simplest solution to that was to knock off a corner of the board.

Finally I connected everything together and “stuffed” it into the box. I say “stuffed” because, well, it’s a sloppy jumble of wires going everywhere all kind-of crammed into that space. I thought about making it neater, or maybe doing a more sophisticated PCB that would eliminate much of the wiring, but in the end this was a quick-and-dirty job. As such, the extra length of the wires was needed in order to be able to assemble and disassemble the device for testing and/or changes.

If you make the wires too short then there’s no room for getting the circuit board into and out of the box without having to desolder something. The lead length also doesn’t matter too much in this case since it’s all low-voltage DC, and the heat dissipation requirements are vanishingly small – so “stuff” it is.

Make one connection at a time until everything is wired up, make a final test, then it’s stuff-in-a-box. 🙂

Once the lid is on and it’s up and running it’s a pretty solid and fairly professional presentation. The LEDs all work as expected, and the orientation of the toggle switch and the red “do-not-tune” light make the user interface intuitive. With the switch to the left (away from the controls) the red LED is on and the controls are locked. With the switch to the right (toward the controls) the tuner is free to tune and can be reset with the push-button.

I’ve thought about doing something more sophisticated with this… and maybe putting it in a heavier box; but ultimately it does the job, has been reliable, and there really isn’t more to do!

In future, maybe, if I built a feed-point tuner I might like to have it provide information about its’ tuning solution and even provide an analysis of the antenna… or perhaps also take commands to fine-tune the solution or act as a pre-selector … but that’s just me dreaming and NOT what this tuner does. This one is designed to be simple and reliable and it hits those marks very well.

This controller seems to hit those marks too — with just one extra blinkenlight 🙂

Jan 032022
 

I wanted an antenna that would be good for all HF bands; that would have reasonably good performance characteristics; and would be reasonably stealthy. Clearly, a wire antenna of some type… but what type?

There are dipoles that would work, and I’ve used them in the past, but they pose a couple of problems– mostly stemming from the heavy feed line and balun hanging in the middle, and the limited options for hanging a multi-band dipole on my property.

Then I looked at an inverted L… but that would need a counterpoise, and probably a complex one at that. Then it occured to me that if I connected the counterpoise to the far end of the inverted L I would actually have a large vertical loop – and that might even perform better! So that’s what I built.

I had a few other constraints to deal with though. For one thing, kids play in my yard (often without my knowledge or permission), so I would have to make sure that the antenna stayed safe for anyone around it and that all of the low, reachable elements were covered. I also wanted to have the tuner at the feed point in order to have minimal losses in the feed line.

The final design would have the vertical sides of the loop going up some trees about 65 feet apart; the bottom of the antenna buried a few inches under ground; and the tuner up about 10 feet in a box to protect it from the weather as well as any uninvited fingers. The wire itself would be insulated, and parts of it would be in conduit to protect it from the weather, squirrels, and other hazards.

The tuner itself is designed to be out in the weather, but by putting it in a box the termination points are hidden away, the tuner is further protected from the elements, and I have the option to eventually put additional equipment in the box.

The first step was to call Miss Utility and get the yard plotted so I could avoid my fiber and other possible hazards. Then we could begin burying the conduit. I say conduit, but really, it’s cheaper than that! I opted to use lawn sprinkler tubing which comes in various diameters, is designed to survive under ground, and is easy to work with.

The smaller diameter tube would go between the trees and be just big enough to carry the bottom part of the antenna. A larger diameter tube would go between my lab (in the basement) and the closest tree in order to carry the feed line and various other cables.

The next step was to assemble the loop and get it ready for installation. I would hire a “tree guy” to climb the two trees and install the hardware… but before that could happen I would have to have all of the ground work complete and ready to go.

Now, as a side note, my usual methodology is to do all of the math and drawings in meticulous detail and then execute that plan. This was no different. I had spent hours figuring out precisely what size loop would be required to have the least conflict on multiple bands and give the best performance overall. Everything would be precisely measured ahead of time so the installation would go off without a hitch and the end result would be perfection. You can probably tell by now that’s not how things worked out right?!! Indeed this experience broke me out of my shell and started me down a path of engineering both by intuition and by design somewhat abandoning my tight grasp of all things mathematical in favor of a more holistic approach— more on that later.

With the conduits in place the antenna wire, made from common electrical wiring, would need to be pushed through the conduit and various hardware installed. This included pulleys for each end to allow the antenna wire to move freely in the wind; and some insulators as strain reliefs in strategic locations to keep the wire from moving “too freely.”

The first excursion away from my usual engineering practice was how I treated the installation of the insulators. I had in mind to avoid joints and to keep the original insulation in place as much as possible. So, instead of a complicated arrangement at insulator locations I decided to simply push the wire through and tie a simple knot. In theory this tiny additional inductance would be invisible — and if that turned out not to be the case then I could always strip the insulation later and solder the joints at the insulators. As it turns out, my assumption about the inductance was correct and I never needed to rework the insulators.

The physical installation on the trees would be done using eye-bolts. These are much easier for a tree to handle than anything tied around a branch or trunk because they create only a tiny hole which the tree can usually heal. In contrast, loop tied around the tree could eventually strangle it or a the very least impose a much larger wound that might be too much for the tree to handle.

On installation day the arborist made a mistake – or more practically, uncovered one of mine. I had measured the antenna wire to precise specifications and had expected both ends of the loop to be up 30 feet. On the taller tree he installed the top pulley about as high as he could get it. My wire was too short for that — so either I would have to have him climb up again and fix it or I would have to adapt. I decided that in the end height would be more useful than precision… thus my second excursion from my usual “design first” paradigm.

I spliced in some extra wire to make up the difference. I used a Western-Union splice, soldered it, and wrapped it in heat-shrink tubing. As it stands now the “short” side of the loop goes up about 30 feet as originally planned and the “tall” side of the loop goes up about 45 feet. The loop runs roughly east to west (120° – 300°) between the two trees – though this orientation turns out not to be very important based on the propagation data I get from WSPR results.

The wire is hung with sufficient slack to allow the trees to sway in the wind without ever creating a high tension on the wire. This is much easier in this case than trying to configure some kind of weight or spring mechanism. As it turns out the extra slack doesn’t seem to affect antenna performance very much, and since this installation has now survived several years (initially built in 2014 and it is now 2022) the physical installation seems quite sound.

It’s probably also worth pointing out that the vertical portions of the antenna are running up the trees, and yes the bottom is technically under-ground. Shouldn’t that be a problem? Trees are conductive (sort of)! and the bottom of your loop is in the ground!! Are you mad!!??.

Yes, yes I am, and, it doesn’t matter 😉 This was never going to be a perfect antenna, just a good one. The tuner does a fantastic job of figuring out the various vagaries of the adjacent conductance of the ground and trees; and in the end the performance of the antenna turns out to be quite good in all weather.

Ultimately, though it might be fun to have an antenna farm where I could perfectly build all of my crazy ideas, I must bend to practical circumstances. What is kewl about this design is that almost anybody could build it almost anywhere and expect reasonably good performance. I’ve even considered using something like this on field day by just laying the bottom half of the loop on the ground stretched between a couple of cinder blocks. If I ever get to try that I’ll let you know how it goes– but it should work, and basically just requires a couple of reasonably high vertical points, a tuner, and a spool of wire.

The tuner box and various electrical conduit and outdoor boxes come from home depot. The goal is to keep the weather out and keep the electronics happy. That turns out to be pretty hard to do as the weather is relentless – so I decided not to skimp very much on these parts.

The tuner is an SGC SG-237. Currently I’m running the second of these devices on the antenna. The first one “went deaf” a couple of years ago for unknown reasons. I recently replaced it with an identical model. Testing that and being reminded of the antennas’ performance is what prompted me to finally publish this article.

The tuner goes in a weather proof box that’s large enough to house any additional equipment I might want to post outside on the tree. In addition to the feed line and control wiring I also pushed a cat-5 cable out to the box in case I want to run some POE driven computing gear and other devices. So far, I’ve not done that, but I do have ideas.

A second insulator acting as a strain relief is mounted on the antenna above the tuner box so that the wire doesn’t pull on the box nor the tuner.

In order to keep things serviceable and to provide some safety I installed a couple of boxes at ground level between the sprinkler tubing that goes to the lab and the outdoor electrical conduit that runs up to the tuner box.

One of these boxes acts as a connection point between the control cable from the lab and the control cable coming from the tuner. The other box connects the feed line from the tuner with the feed line from the lab via a lighting arrester: Alpha Delta model TT3G50.

All of these are grounded via an 8 ft ground rod driven at the base of the tree right next to the boxes.

Lately I’m re-thinking the screw terminal strip for the control wires and considering replacing those connections with heat-shrink soldered connections. It turns out that the time between servicing these connections is fairly long and I’d like to have better long-term connectivity than I can expect from screw-down terminals.

When I’m not otherwise using the HF rig I generally run WSPR continuously. Since the tuner refit I’ve been running WSPR at 2 watts on all HF bands with some pretty spectacular results. I can expect to see contact to Australia, Hawaii, Europe, Africa, the Arctic and Antarctic on a daily basis – usually on multiple bands.

The sweet spot for the antenna seems to be 17M but all bands 160 – 10 are usable, and 20-15 are quite good (sun spots permitting). The worst SWR I get is on 80M at about 2:1.

Here is a tweet I posted showing good DX WSPR contacts on 3 bands simultaneously. If you build something like this please do let me know how it works for you.

May 182021
 

The mathematics of complexity dictate that
the flapping of a butterflys’ wings might lead to
a hurricane on the other side of the world,…
or, they might not. It’s not up to the butterfly
and even if there is a hurricane the butterfly
probably won’t notice; and even for a god
there may be no better way to know the outcome
than letting the computations pay out.

This does not mean that the butterfly is powerless
nor inconsequential.

The Pauli exclusion principle states that
no two particles can occupy the same quantum state.
So, just by its’ very presence the butterfly has forced
countless other particles to be elsewhere; and
by the flapping of its’ wings it has rippled out
countless changes into the universe that
continue to drive change forever forward in
subtle ways.

Even the photons, traveling at the speed of light,
experiencing their beginning and end simultaniously
in the absence of time, don’t know where
they will end up… but every one of them matters.

The universe is a question pondering itself
and we are each a part of the answer.

Flap your wings!

Apr 112020
 

So, this is the edge?
Or, is it the edge?
It’s hard to know.
Like the event horizon of a massive black hole,
it bends a little more steeply at every step;
but never so you would notice.
It’s as if I know I’m being swept away,
but as anything caught in the current,
I feel no movement…
just a persistent screaming in the back of my mind –
an itchy thought –
a superposition of sheer panic, and dead calm.
Like camping on the boundary
between the immovable object
and the irresistible force –
carefully balanced so that time stands stands still;
with unimaginable energy, poised
just a twitch away from cataclysm.
I stare into the abyss, and perhapse, later,
if not otherwise occupied,
I will sit in the dark and sink slowly into madness.

Apr 102020
 

I wish I had the magic words
to bring you safely back (to me)
to feel your touch
to hear your voice
and hold you by my side

I watch your likeness on machines
hear your vibrations in my ears
you’re far away
but oh so close
a sparkle in my mind

I wish I had the magic words
but somehow they won’t come (to me)
still I can feel
your memory
stirring deep inside

Impulses and waves, electricity,
invisible forces, flow in between
I don’t recall imagining
a world unreal as this

Reach out to me from where you are
as I reach out from here (to you)
imagine it’s
my warm embrace
and don’t let it subside

I wish I had the magic words
to bring you safely back (to me)
to feel your touch
to hear your voice
and hold you by my side

Dec 202019
 

It seemed obvious enough. I mean, I’ve been using these for as long as I can remember, but the other day I used the term SOP and somebody said “what’s that?”

An SOP, or “Standard Operating Procedure” is a collaborative tool I use in my organizations to build intellectual equity. Intellectual equity is what you get when you capture domain knowledge from wetware and make it persistent.

In order to better explain this, and make it more obvious and shareable, I offer you this SOP on SOPs. Enjoy!

This is an SOP about making SOPs.
It describes what an SOP looks like by example.
SOPs are files describing Standard Operating Procedures.
In general, the first thing in an SOP is a description of the SOP
including some text to make it easy to find - kind of like this one.

[ ] Create an SOP

  An SOP is a kind of check list. It should be just detailed enough so 
  that a reasonably competent individual for a given task can use the
  SOP to do the task most efficiently without missing any important
  steps.

  [ ] Store an SOP as a plain text file for use on any platform.
  [ ] Be mindful of security concerns.
    [ ] Try to make SOPs generic without making them obscure.
    [ ] Be sure they are stored and accessed appropriately.
      [ ] Some SOPs may not be appropriate for some groups.
      [ ] Some SOPs might necessarily contain sensitive information.

  [ ] Use square brackets to describe each step.
    [ ] Indent to describe more specific (sub) steps such as below...
      [ ] View thefile from the command line
        [ ] cat theFile

        Note: Sometimes you might want to make a note.
        And, sometimes a step might be an example of what to type or
        some other instruction to manipulate an interface. As long as
        it's clear to the intended reader it's good but keep in mind
        that this is a check list so each instruction should be
        a single step or should be broken down into smaller pieces.

      [ ] When leaving an indented step, skip a line for clarity.
      < > If a step is conditional.
        [ ] use angle brackets and list the condition.

  [ ] Use parentheses (round brackets) to indicate exclusive options.
    Note: Parentheses are reminiscent of radio buttons.

    ( ) You can do this thing or
    ( ) You can do this other thing or
    ( ) You can choose this third thing but only one at this level.

[ ] Use an SOP (best practice)
  [ ] Make a copy of the SOP.
    [ ] Save the copy with a unique name that fits with your workflow
      [ ] Be consistent

  [ ] Mark up the copy as you go through the process.
    [ ] Check off each step as you proceed.
      Note: This helps you (or someone) to know where you are in the
        process if you get interrupted. That never happens right?!

      [ ] Brackets with a space are not done yet.
      [ ] Use a * to mark an unfinished step you are working on.
      [ ] Use an x to mark a step that is completed.
      [ ] Use a - to indicate a step you are intentionaly skipping.
      [ ] Add notes when you do something unexpected.
        < > If skipping a step - why did you skip it.
        < > If doing steps out of order.
        < > If you run into a problem and have to work around it.
        < > If you think the SOP should be changed, why?
        < > If you use different marks explain them at the top.
          [ ] Make a legend for your marks.
          [ ] Collaborate with the team so everybody will understand.

    [ ] Add notes to include any important specific data.
      [ ] User accounts or equipment references.
      [ ] Parameters about this specific case.
      [ ] Basically, any variable that "plugs in" to the process.
      [ ] BE CAUTIOUS of anything that might be secure data.
        [ ] Avoid putting passwords into SOPs.
        [ ] Be sure they are stored and shared appropriately.
          [ ] Some SOPs may require more security than others.
          [ ] Some SOPs may be relevant only to special groups.

[ ] Use SOPs to capture intellectual equity!
  [ ] Use SOPs for onboarding and other training.
  [ ] Update your collection of SOPs over time as you learn.
    [ ] Template/Master SOPs describe how things should be done.
      [ ] Add SOPs when you learn something new.
      [ ] Modify SOPs when you find a better process.
      [ ] Delete SOPs when redundant, useless, or otherwise replaced.

    [ ] Completed SOPs are a great resource.
      [ ] Use them for after action reports.
      [ ] Use them for research.
      [ ] Use them for auditing.
      [ ] Use them to track performance.
      [ ] Use them as training examples.

  [ ] Collaborate with team mates on any changes. M2B!
    [ ] Referring to SOPs is a great way to discuss changes.
    [ ] Referring SOPs keeps teams "on the same page."
    [ ] Referring SOPs helps to develop a common language.
    [ ] Create SOPs as a planning tool - then work the plan.

  [ ] Keep SOPs accessible in some central place.
    [ ] GIT is a great way to keep, share, and maintain SOPs.
    [ ] An easily searchable repository is great (like GitTea?!)
      [ ] Be mindful of security concerns.

Oct 182019
 

happy thoughts please
push away the darkening gloom
that threatens to consume
the room between my ears
by stoking all my fears
reminding me of tears
the years that went by wrong
the promises broken
the dreams undone

happy thoughts please
wash off the pain
remove the stains
repair the wonds
evict the gloom
before it turns the light to pain
the morning sun to a cold harsh intruder
painful brutal beastly heartless and unrelenting

happy thoughts

please

Sep 062019
 

I should have done this forever ago… but I’ve decided to put the brick (flex6300) to work when I’m not using it 🙂 From now on, mostly, when I’m not using it for something else or whenever it won’t interfere with other research I’ll be running WSPR on a VM using the 6300 and my large vertical loop.

FLEX6300 + 60M-Circ Vertical Loop Running WSPR