Bicycle Mobile Radio

Battery is mounted non the stem.

The HF radio is in the pouch hanging from the handlebar.

The ham stick is behind the seat by the flag.

I’ve been an amateur radio operator for a few years. My goal, back in 1989 when I first earned my license was to put a side-band station on the air that generated a kilowatt carrier. During those subsequent year I’ve tried many of the available digital modes. But none of them, with exception of Packet, caught my interest like that of the old tried and tested Morse code. Eventually, I abandoned my quest for the 1,000 Watt station and went the other way – low power, or QRP.

For a few years I concentrated on mobile radio, not with a car, but with a bicycle, and then a tricycle. I’m not a pioneer of this area, by any stretch. And I probably haven’t done as well as many others have. But I’ve had fun. A lot of fun.

One afternoon while pedaling around some Texas back roads with my five-Watt rig (about the same power required to light a Christmas tree lamp), I checked in with the Maritime Net. The net control was somewhere in Wisconsin, as I recall. I received a fair signal report – a home-run considering the power I was using.

I was preparing to sign when a Musher, a lady who drives sled dogs, broke in from North Dakota, stating she’d like to talk with a person on a bike.

That was my greatest distance with 5 Watts from the eat of a bicycle and a store-bought ham stick antenna.

magnolias and antennas

magnolia_antennas

bending with the wind

de bill, k7WXW

The magnolias, one in the open, the other behind the scotch pines, are a couple of days from full bloom. Like most of the flowering trees around here, they happen in a burst. When they do, Amy harvests a branch or two for flower arrangements but mostly we enjoy them where they are.

This morning, however, there are two buckets of branches in the dining room, and on the porch, a pan piled with not-quite-flowering buds. My phone beeps while we are filling the second bucket: high wind alert. Old news around here. The gusts are sweeping flowers from trees all over the neighborhood and both magnolias will, I think, be bare before noon.

My antenna masts are two scotch pines, a birch, and a cedar. At this moment, the top of the birch is sweeping eight foot arcs, the cedar and pines, three or four. The dipole and end fed are, so far, moving with them. I finish helping Amy and head out to take care of the antennas.

At the base of each tree is an eye hook and a cleat. The pulley lanyard is cleated and the line that runs through it is attached to one end of an antenna. I can take the antennas down (and put them back up) without climbing. My original design included a tensioning spring between the eye hook and the antenna rope. Then I decided I was over-engineering things and didn’t install them. I watch the treetops bend, untie the rope, add four feet of slack and retie it. I move to the cedar and repeat the process. The gusts come and go. In the calm moments, the antennas dip toward the yard, forming deep, graceful curves. I’ve probably dodged losing one or both of them. Good thing I was home.

I spend the morning apparently working, but mostly I am watching the trees. The magnolias are holding up better than I expected. Of course. Trees are built to bend. On the way to more coffee I take the long route, through the yard. The dipole lifts and drops eight or nine feet in the middle. Amy is in the living room, turning blooms and branches into flower arrangements.

My antenna wasn’t built for this. If I hadn’t been around this morning, I’d have a tangle of wire in the middle of the yard rather than an antenna above it.  I am reminded that an antenna on paper is one thing, spanning my house, it is something else entirely.

On my laptop, a dipole is a wire of particular length and height, fed with more wire, and connected to a radio. EZNEC tells me it will have a certain resonant frequency and radiation pattern. A couple of websites help me estimate the cost, and so on. Before I get an antenna into the air, my problems have names like efficiency, loss, and noise. It’s all straight lines and numbers, like this diagram from the ARRL. Later, when 18 gauge wire, three or four insulators and a couple of pulleys are involved, the problems become unrelentingly physical: wind, tangled ropebranches, house-in-the-way. After all this time, I should not be surprised by this but I am.

Pines and magnolias move with the wind. In good years, they weave their branches around one another, grow over the house, drop some buds in a storm. In bad years, not so much growth, maybe some lost branches. They are not impervious to the weather – witness the ragged stump that is the top of one of the antenna-free scotch pines – but their organic responsiveness helps them survive most sudden or severe environmental changes.

Good designers can’t work slow as trees but they can mimic their way of adapting by asking questions. Sometimes obvious, what if something that isn’t part of the system changes? and sometimes not: how to get the feedline away from the gutter? Questions can be in the form of calculating or simulating or breadboarding or just going outside and looking at the trees. Whatever works! The important thing is asking. Don’t get lulled into thinking, there’s never lightning around here or when was the last time the wind really blew?

Good design isn’t organic like a tree growing, it is methodical and pragmatic. But the designer who blends good design practice with the willingness to not-know ends up with a tree-sturdy design: it doesn’t fail whenever the world outside isn’t quite as neatly organized as one’s lab notebook.  Which, by the way, is pretty much always. How do you not-know? Simply questioning everything during the design process is a good start. Your assumptions, the boundary conditions of the problem, your taken-for-granted knowledge? Put it all up for grabs, at least for a little while.

I used to begrudge the time required for this kind of questioning. git ‘er done!  was my motto. The reward for such parsimony was often a tangle of wire, glowing transistors and the like. Or when I made time for questions, I would dismiss the answers, as I did with the springs. Oh, that will never happen!  By now I’ve let plenty smoke out of stuff; I allow lots of not-knowing time.  My “dump the springs” decision suggests that I still need work on the pay-attention-to-the-answers-you-get end of things.

Late afternoon. The wind is a slow steady breeze. I was wrong, the trees aren’t bare. The porch is covered with petals but the magnolia is still mostly flowers. The dipole is drifting up and down a foot or two. I decide to give the wind another hour or two of free rein before taking the slack out and head to the basement to find some springs.

Writing Chapter One – Tips from D. Wallace Peach

Mundus Media Ink

by D. Wallace Peach

I’ve wanted to write about first chapters for a while, primarily because they’re so important. After all, they’re the gateway to Chapter 2 and getting a reader to Chapter 2 is a fantastic idea.

I did some research and almost instantly the rule-resistant rebel in me kicked in. She’s the writer who scowls at formulas, who insists that form has to fit the story, not the other way around. She’s the reader who doesn’t want to read the same story over and over with different titles.

Well, I suppressed the first-born smarty-pants part of my personality and learned a few things.

First, I learned that there are actually a number of perfectly legitimate types of first chapters. Writer’s Digest has a great article by Jeff Gerke that describes 4 approaches with examples (summarized here):

  • The Prolog – A prolog is an episode that pertains to your…

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looking for trouble

part last: how to look

de Bill, K7WXW

Generally, when something in my shack stops working, I start with the basics: are the cables right? Have I turned on the power? Operator error is always the first hypothesis. When I’ve worked through the obvious stuff and don’t have a clue, I turn to the interwebs. Whatever I am trying to fix has probably been used, torn apart, repaired or modified by someone somewhere who subsequently wrote an email or blog post about it. A thorough search usually results in a pile of helpful files, bookmarks and contacts.lookingfortrouble2

Today, unfortunately, my first search didn’t reveal much so I went to plan b: asking for a little help from my friends.

Email lists and forums – what we used to call bulletin board systems and newsgroups – are my connection to hacker/maker/ham communities that always know more than I do about whatever piece of gear, technology, or software I am trying to make work, repair or hack. There’s a vast store of tribal knowledge in such places and on most lists, people are happy to help you if you do your homework and ask specific questions. In this case, I distilled what I needed to know into two questions, wrote a paragraph describing the symptoms and what I’d done so far, and sent it to a QRP list where I hang out. I write an email like this once or twice a month and the result is almost always helpful.

My email netted me a schematic of the base unit, good troubleshooting advice, and references to several articles about SWR meters. The articles helped me understand the theory and gave me pointers to other articles, along with the callsigns of hams interested in SWR meters and directional couplers. I used this info to do another web search and soon had a stack of articles, schematics, and photographs, more than enough to figure out how the WM-1 works and how to fix it.

It took a couple of hours to go through all the material. Along the way I learned a lot about directional couplers and RF measurement.  I was able to make some good guesses about nature of the problem, and come up with probable fixes. This is one of the benefits of I-have-to-fix-it-myself gear: figuring out what’s wrong with something is a great way to learn how it works.

I made a repair list and a plan for home brewing a new RF detector. I should be able to fix the old meter but building a new one will give me a backup and help me convert all the theory I’ve been digesting into a real piece of gear. Another perk of fixing-it-myself: the satisfaction that comes from using gear that I’ve repaired, modified or built myself.

I am glad I lost the habit of immediately replacing stuff that doesn’t work. My unusual meter spike has turned into a file of interesting articles, a repair project, a cool home brew project and a must-to-read list of RF design tutorials. I know a little more about SWR, RF power measurement, and directional couplers and I have had interesting conversations with three long time hams. If, three days ago, I was wondering about the wisdom of buying a flaky third-hand meter, today it appears to be a pretty good deal.

looking for trouble

part two: all the things it is not

de Bill, K7WXW

The sun is almost up when I let the dog out, make coffee for Amy, and sit down to check my email. I have three replies to my query. Someone sent me a schematic of the main board, someone else, three or four references to directional coupler designs along with technical data and photographs from three or four watt meters he built. The last email is a reminder not to rush through troubleshooting. I get my notebook.

My friend’s reminder is timely. Like most fools, I tend to rush in. Making a plan attenuates this tendency. My curiosity helps, too. Why doesn’t this work? is such a great question. I don’t just want to get this meter back on line, I want to know what makes it go. Troubleshooting is one way of figuring that out; maybe the best. Besides, I don’t have a spare meter. Until this one is fixed, I am without. Using the emails, schematic, and a little common sense, I make a list of things to do, then head downstairs.

After disconnecting the power and undoing the wing nut that holds the ground strap, I pull the desk away from the wall and start working through my list. I remove and test the coax cables and feedline. I examine the ground connections. Everything checks out. I make a note to look at the cables and connections at the outside panel, too. So far, though, no obvious problems.

I have two antennas, each going to a matchbox tuner. Between the rig and the tuners is a coax switch. The configuration is a bit complicated, so I take the switch out and test each antenna path separately. A basic troubleshooting rule I learned as an engineer: keep it simple. Complexity is hard to understand, let alone test. The corollary: change one thing at a time. Two variables changed means four possible outcomes, three means nine, and so on. Don’t make things harder than they already are!

I check the coax switch with an ohmmeter. It is good, too. I put the switch in line with the two tuners and test again. The antennas load on all bands. I make more notes. I’ve eliminated almost everything but the meter. I make sure I have cabled the radio correctly, push the desk back, and head upstairs. I haven’t completely nailed the problem down but I have eliminated a lot of possibilities. That is a good morning’s work; time for breakfast.

looking for trouble

part one: when stuff breaks

tshoot_040717

de Bill, K7WXW

While tuning through the 40 meter band, I notice the SWR meter spike and return to zero. Ten minutes later, it happens while I am not touching the rig. That’s weird, I think, but the net starts in twenty minutes. I don’t want to start taking things apart. I decide look into it later.

I drop to 80 meters, lower the RF power to five watts, and switch to AM. When I key up, the SWR meter goes to max and stays there. Adjusting the matchbox makes no difference. I move back to 40 meters. The same thing happens. Weirder. It worked ten minutes ago. Looks like I am taking things apart. With the meter out of line, I match the dipole on both bands. Putting it back in, I don’t.

Bad cable? I swap in a new one and check the old one with a ohmmeter. The new cable doesn’t make a difference and the old one is good, at least at DC. While I am switching the cables, I bump the meter and the receive audio gets a lot louder. I try to match the antenna again. Success. Could my third hand meter, an Autek WM-1, be the source of my woes?  I take it out of line and get ready for the net. For now, I can use the rig’s SWR meter.

I am embarrassed to admit this, but in an earlier life, I would have chucked the WM-1 and ordered something shiny and new. I was a busy guy.  Who had time to figure out why something didn’t work, right? In this life, I finish the net, put the meter on the bench and start taking the case apart.

I look for obvious problems: loose wires, cracked components, bad solder joints. The solder work is questionable and the sensing toroid isn’t glued down but there are no glaring (that is, easy to see) faults. I make a note to reflow the solder on all the connections and glue the toroid into place.

The instruction manual notes that unexplained SWR spikes aren’t anything to worry about. I speculate for a moment about career path of whoever approved the manual. There’s a schematic for the detection circuit but none for the main board and no explanation as to how it works. Not helpful.

I do a quick web search and turn up a few posts about the odd behavior I am seeing. Unfortunately, none include a fix or schematics of the base unit. I can’t call customer support; Autek disappeared years ago. I am not sure what to try other than cleaning up the bad soldering, so I go to plan usual: asking for help from people who know a lot more than me.  I send an email to the QRP list and set the meter aside for the night.

Watching the Trains

Grounding Bars and Bolts

Fine Tuning My Amateur Radio Station

de Bill, K7WXW

The ground bar is bolted to the shelf. The grounding straps of tinned copper braid between the bar and my rig, power supply and tuner, are in place. I am holding the last one, which will connect the case of the AC line filter to the bar, in my hand. The filter is on the floor near the wall outlet. But I can see there is a problem with the strap. Being four feet long, it will make a good antenna for any stray RF lurking around. Last thing I need is another entry point for noise, so I put it down and look for my notebook.

Other design decisions aren’t working out either. To get behind my rig, I have to move the desk. To move the desk I have to get out a quarter-inch socket wrench and unhook the copper strap that ties the ground bar to the rod outside.  Inevitably I need to crawl under the desk to retrieve the bolt after dropping it.  When I am done, I have to reverse the procedure, hopefully without the dropping-the-bolt step. This is not, as they say, an optimized process.

Sidenote: My friend Scott, N7NET, offers a tip for starting nuts in hard-to-reach places: dab a little Vasoline in the back of the socket to hold the nut in place until it catches the threads.

Apparently good paper designs often fail when they encounter real world voltages, screws, and transistors.  Spectacularly sometimes, too, as in what could you have possibly been thinking when you designed it that way? Mostly though, designs fail in small ways: a hard to reach screw or an oscillating amplifier.  Even good designers – and I am not in the category – have these problems. It is really impossible to know beforehand exactly how the thing we are designing is going to be used until someone is actually using it.

A piece of gear can’t get much simpler than a copper bar with holes drilled in it, a couple of standoffs, and a fistful of 4-20 nuts, lockwashers, and bolts.  Bolt the bar to the desk, secure each ground strap with a bolt, lockwasher, and nut, done. What could be easier? Something other than a ground bar, apparently.  The way I designed my system, undocking the main ground to get behind the desk is a giant hassle. The ground strap to the AC line filter is too long. And with a single bolt, nut, and washer per strap it takes two hands and two tools to make or break a connection. It all adds up to a list of changes that I didn’t know needed to be made until I actually put the ground bar together and tried to use it. And it also reflects a simple fact: paper designs, however carefully done, almost always need a tweak or three.

My first inclination is fix it now! Giving into this impulse almost always turns out, even in the simplest cases, to be a bad idea. My first unvarnished solution to a problem is usually (never) my best one. Sometimes it is not even my second or third best one. I don’t trash the first thing that comes to mind, but I don’t stop with it, either. I just see it as the start to a list of potential fixes to particular problems.

Even well-designed commercial gear doesn’t get through the design-build-use cycle without lists like this being written. When I was an engineer, we called them engineering change orders, ECOs for short. ECOs are another version of my lab notebook: what is the problem, what is the fix, what does it affect, how much does it cost? In the commercial world, an engineer has to write an ECO and get it approved by the people who live with the product and modifications made to it: manufacturing, marketing, testing and so on. Here’s a truth: those folks don’t like change. It mucks up their day. To get an ECO approved that engineer has to think through the problem he or she is trying to solve in a way that makes sense. Improvisation rarely wins the day.  Whether I was the designer or the design team manager, ECOs were my antidote for the spontaneous fix.

I don’t have a marketing department and I manage all the manufacturing and testing around here. The only person who has a bad day due to a poorly thought-out fix is me. That said, I don’t enjoy re-fixing a fix that didn’t work, so I address problems by following my homebrew version of the engineering change order process.

I start by looking at my original design. What was I trying to do? Did I miss something? I make a list of the problems and ask if any of them arise out of the original requirements. For the ground bar, ground straps should be as short as possible and in a star configuration. That requirement limits, among other things, where I can place the ground bar. If a requirement causes a problem and I can’t come up with a fix, I either live with it or I change the goal. Other problems come up because how I thought things would work is different from how they actually work. And, finally, there are the things I just get wrong. Now I have a to-be-fixed list, based on actual use, that reflects my original design goals.

Next, figuring out possible solutions. There are rarely more than three or four to consider. I just don’t have that many good ideas. As always, I write all this stuff down. Why? Mostly I don’t like having the same bad idea more than once.  The end product of this process is my homebrew ECO: a detailed lab notebook record of the what, why and how of whatever it is I am fixing, without all the check boxes and signature blocks one finds in the commercial version.

When I actually don’t know what might work, I go off to do some research. Maybe (almost always) someone has had this problem before. Or maybe a data sheet or application note will give me ideas. And sometimes simply setting the list aside for a bit does the trick. The list that comes out of this process will always be better than randomly trying something and hoping everything will turn out okay.

Now I have fixes I like. I start working through the list. The bolts are installed from the bottom of the bar with a lock washer and nut on the top side so they don’t have to be removed when I disconnect a ground strap. The  strap that runs outside is held with a wing nut instead of a nut now, so I don’t need a wrench or nut driver to take it off. The AC line filter is mounted to the underside of the desk with a six-inch, rather than four foot, ground strap. I can’t do much about needing to disconnect the outside ground every time I need to get behind the desk; no changes on that front.

After the fact, the fixes seem pretty simple and might hardly worth all the record keeping. Bill, that sure seems like a lot of work for a small problem. Couldn’t you just try something and see how it worked? Perhaps. Maybe though, simple fixes are simple because they are thoughtful and thoughtfulness is the result of writing down what one is doing and why.  It took me longer to write this post about the process than it did to actually do it.  That isn’t always the case. The chance of getting something wrong in a design goes up as the square (or worse) of the complexity. More parts, more chances for error. If that’s true, a process that includes time for making, testing and documenting changes seems prudent, even for a ham building gear in the basement.

I disconnect one of the ground connections to re-route it so it won’t block access to one of the antenna feeds. After checking everything against my wiring diagram, I plug gear into the new AC filter and the filter to the mains, then push the desk back against the wall. Getting behind the rig is a lot easier than it was two hours ago. Fix accomplished and later, when I am trying to remember why I did what I did on this project, I have my notes. It works.

It Takes A village

Spring is making every effort to stay and I’m glad to see it. With it come the brave, wild flowers. And I enjoy the color they provide before the county comes around with their mowers.

It was April when my wife had just returned home from a month-long-stay in the hospital. I always remained within earshot. And while doing so I spotted a dragon fly perched on a limb about shirt-pocket level. His large eyes are what caught my attention. After I’d studied him for a short time he took flight, circled me and then returned to his post. That’s when it occurred to me that he was not out for some fresh air. He was on guard duty. Somewhere in that thicket something involving his species was occurring and his job was to keep predators at bay. He was a brave little creature. I could have crushed him.

A couple of decades ago I was at home writing while Barb was working. She was a nurse. A new hatch of crows were in the timber behind where we lived and they sounded like a herd of tree frogs as they found their crow voices. Then everything went silent. I paused to listen and when they didn’t resume their “chatter” I slipped outside to see what had happened.

The timber came out to a point near an old pond and as I scanned the area for anything unusual I noticed a lone crow, an aged crow, perhaps the alpha crow, perched on a limb facing the road. Slowly, I changed locations in order to see what he was watching. There, on the power line sat a hawk. It was a stand off.

Minutes passed. Perhaps two or maybe three. Then as the hawk emitted a high-pitched screech he vaulted from his perch and headed north.

The crow maintained his station for a longer period, Then he flew off the limb, made a one-eighty and headed back into the forest.

An instant later the youngsters resumed their practice at becoming crows.

Hilary, when she was still First Lady, stated that it takes a village to raise a child.

Perhaps it takes a village to raise a crow as well.