Siting the Towers and Antennas

With 50 acres of land you might think that I have no constraints on where I place towers. Of the 50 acres, a few are allocated to the house and immediate yard area, 20 are being tilled for hay, and the rest are a mix of forest, bush and swamp.Yet there are always constraints beyond the common one of lot boundaries.

Let's look at the constraints I am most concerned with.

• Houses: As much as possible you want to maximize the distance from RFI emitters and receivers and to protect against damage or injury should a tower or antenna fall down. In an urban environment this can be difficult. A rural setting opens more options, though limited by the next criterion.
• Length of transmission lines and control cables: Long conductor lengths are expensive and can incur unacceptable loss. The shorter the better, unless you are working with a large budget.
• Trees, fences, utilities and other barriers: Much grief can be avoided by siting towers and guy anchors out in the open. The closer they come to roads, utilities and trees the greater the risk of accidents. Trees can be deceptive. Their roots can grow out sideways, especially over rocky ground, and a small tree will grow into a threatening giant. Obstacles will also impede the raising and lowering of all but the smallest antennas, and may require a tram from a more distant patch of open ground. And as they say, call before you dig. Do you know where all your utilities, drainage pipes et cetera are buried?
• Tillage: In a rural setting the conversion of perfectly good land from crops to antennas can be scandalous in the neighbourhood. In some jurisdictions it can even be illegal. If you are in this situation be very careful. For example, the tillable land on my property (~20 acres) is hayed by a local farmer. I want to site and orient the towers in a manner to maximize his access to the land. They will appreciate the gesture.
• Rock: In this part of the world rock is a frequent excavation impediment. At my previous house my 1985 tower requires breaking through 3' of shale to achieve the required depth. The same had to be done when I built a new house in 1992. Excavation equipment to break rock is expensive. At my new QTH the rock is managable by hand digging for the self-supporting tower, but that was due to careful site planning: I chose a location with perhaps 2' of well-settled soil above the natural grade. Avoid rock if you can because it can be difficult and expensive to remove.
• Interaction: Even if you never operate on more than one band at a time interaction between antennas is important. The primary ones are damage to inactive receivers and pattern distortion due to mutual coupling. For the SO2R or multi-op contester, or even a fervent DXer simultaneously working two pile-ups, far less interaction can be detrimental.

As you can see there is much to consider. While it is a lot to think through the benefits justify the effort. Why go to all the effort of purchasing a property and then be cavalier planning the placement of towers and antennas? The effort is worth it, even if you cannot achieve an ideal result.

Alternative site plans

Site planning

Even for small stations some advance planning is helpful. It is something I undertook at my previous station when i decided to expand my capabilities. The exercise can pay dividends by avoiding future conflicts and expense. Think carefully about your interests, ambitions and what you might want to tackle in the future.

Draw the layout of your proposed antenna farm, including utilities and adjacent buildings, and even significant distant topographic features.

Alternatively use a satellite view of the area from a service such as Google Maps, as seen above for my property. Import it into one of the many suitable applications that allow you to draw on top of it. I've used Microsoft Powerpoint and Open Office Impress. Precision isn't necessary so these applications are suitable and easy to use.

Initial configuration

Once you stick a shovel in the ground you have made a choice that will constrain your future choices. Choose carefully. I have considered the alternatives and I have put a shovel into the ground. Several shovel, in fact.

The following site plan is the one I am working with. Notice that it is a satellite view of the area around the house with annotations added. I find this approach easier than the alternative of a drawing. Notice that the house is 100 meters the road. Plowing that long driveway in winter will not be fun. Yet this is a great arrangement for antennas because I can maximize the land area within a given radius of the shack.

I'll describe my thoughts on why this configuration is acceptable in the context of my constraints and objectives. The meaning and design of the annotations will also be explained.

The tower annotations are with respect to the physical layout. For self-supporting towers I use a simple yellow circle, for guyed towers the vertices of the triangle are the guy anchors, and for vertical arrays it is the maximum extent or either radials or guys. On both guyed towers I placed a scaled image of a full-size 3 element 40 meter yagi to help with mental imagery.

The scale requires an explanation. Google supplies a scale in the lower right corner. But that is too small to use and it is also inconveniently located. Instead I transformed the scale to the image on my computer screen. I then created several measuring rods in the drawing application that I can paste onto the image, then move and rotate them. You might prefer a more rigourous approach that is not dependent on my screen and application window!

The location of the Trylon self-supporting tower is constrained by the location of the house, septic system, trees and future garage (purple square). This will be first tower to go up, and its construction is underway as of this writing. As previously mentioned, I'm under the gun to get the concrete poured before work on the garage begins. This tower will initially support a large tri-band yagi and 6 meter yagi. It may also be shunt loaded for 80 meters and perhaps 160 until 2017.

The LR20 has been surveyed on the land east of the house as shown on the plan. Excavation is planned for November. I chose the location to minimize visibility from the road, land removed from hay production and distance from the house. Its orientation is not ideal for climbing and, especially, side mounting of yagis. I can work around these minor issues. Over the winter it is unlikely to hold more than inverted vees and a one or two fixed yagi. Next year I plan to raise 40 meter and 20 meter yagis of modest size, or larger if I have the time.

There is provision in the plan for a similar size guyed tower to the south of the house. If I build it one tower will be for 40 and 10 and the other for 20 and 15. This is a common arrangement for contesters since it minimizes interaction among yagis on the same tower by avoiding harmonically related bands and maximizes diversity. If contests are not your passion the need for two tall towers is of less value.

Unfortunately when pointed to Europe the south tower may exacerbate interference with antennas on the east tower. This will have to be addressed with aggressive filtering, and in truth would likely be required in any case.

In the north field I have reserved space for an 80 meter vertical yagi per the design in an earlier article. Alternatively I would put up a 4-square. Spacing from the other towers is sufficient to avoid serious pattern degradation when pointing southeast should any of the towers exhibit a resonance on 80. However there will be no array or even a vertical for 80 and 160 this year.

With respect to noise I have initially avoided placing antennas west of the house. The electrical distribution line is parallel to the road using an easement on my property. If you look closely you'll see the shadows cast by the poles. It is about 70 meters from the house. Antennas would be closer than that.

Notice the placement of measuring sticks to help visualize distances. Then there are the ones further to the east that have a different purpose. These are prospective 100+ meter long Beverages for 80 and 160 reception. Alternatively a 4-square or 8-square circular array could be placed in the wild field to the northeast. Since Beverages are simple and cheap they are more likely to be installed in the near term, and possibly remain my receive antennas of choice.

Receiving antennas are a good choice for the otherwise useless forest and swamp at the eastern extreme of my property. It is not by chance that this area is furthest from power lines and neighbours's houses, and looks towards Europe; it is one of the attractions of the property that caught my eye. I have already been pricing 150 to 200 meter runs of RG6 and control cable. I've also learned to construct small transformers and common mode chokes suitable for 160 and 80 meters.

2017 and beyond

My immediate need is to get towers planted before winter and put up antennas that will get me through the winter and next spring. Starting in 2017 I will begin my long term antenna plan. At this point I don't know how far I'll go, and indeed I prefer to give myself latitude to experiment rather than stick with any fixed ideas.

The site plan must accommodate my particular interests. I believe I've done that. Although now that towers are being planted and their placement constrains my future choices it is beneficial in that I don't have to waste valuable time considering too many possibilities. Or, what we used to called in my business life: analysis paralysis.

My objectives for 2017 include the following, in no particular order:

• 3-element 40 meter yagi. Which design I will select remains an open question. The antenna will go at the top of the LR20 tower and turned with a prop pitch motor/rotator.
• Side mount the XM240 2-element 40 meter yagi on the LR20, rotatable with or without a swing arm to cover the US.
• 80 meter vertical yagi array, including 160 meter vertical.
• Mono-band yagis for 20 and 15 meters, side mounted on the LR20.
• Beverage antennas to cover critical directions, primarily for 160 meters but also to supplement the receive directivity of the 80 meter vertical yagi.
• Tri-band yagis for the Trylon (TH7) and LR20 (TH6, fixed). These are in stock, along with most of the rotators I'll need. One rotatable tri-bander or mono-bander will be mounted above the 40 meter yagi at extreme height.
• 6 meter yagi on the Trylon.
• Heliax for all the long runs

Over this winter, once tower and antenna work must cease, I will begin preparatory work on some of these antennas. There is also work to be done building the shack and automation for rig control and antenna switching.

I also have a stretch objective to raise that second guyed tower late in the season. That event depends on many things, and I may not even want it then or ever. But I expect I will do it no later than 2018. Once built the antennas will be rearranged as I described earlier, with one tower for 40 and 10 and the second for 15 and 20. Large yagis for the high bands will be built or purchased for these towers. Progress of the solar cycle will determine priorities.

Antenna experimentation would benefit from an additional small free-standing tower so that the main towers and antennas don't need to be disturbed. However that may be too much for next year. 

Missing the contests

It feels odd to be writing blog posts while the CQ WW SSB contest is underway. In a way all this typing and thinking makes that lack sting a little less. It is also a welcome break from the hard physical labour of digging. I'll have more to say about digging tower holes later.

Welcome to FN24br

Getting back online after the move was no easy feat. Since I decided to go entirely wireless at the new QTH I was solely reliant on my cell phone. Unfortunately it is old and does not support the newer service bands, and I was roaming on another network. You don't realize how dependent we are on modern communication services until they are missing or unreliable. Amateur radio is not a substitute for ordinary personal and commercial use.

The upshot is that getting internet service arranged and installed took a week longer than expected. Being disconnected had the advantage of keeping me focussed on completing the move and starting on the new station.

One odd problem that occurred with the move had to do with my license and station location. Industry Canada (who regulate amateur radio) found it difficult to update my record in their database. It turns out that when I moved from VE4 to VE3 in 1979 a new record was created rather than updating the one that existed. This persisted when their IT systems evolved and upgrade, and made the problem more interesting. After verifying that I was who I said I was the database was corrected and they issued me a new certificate.

I started simply at the new QTH. With no barriers in the way of getting back on the air, other than the lack of a tower, I unpacked my multi-band inverted vee and hoisted it up a temporary mast. The mast is the same one I used at the top of my bracketed tower. It already has the pulley attached.

A couple of long u-bolts secure the mast to the decayed cedar railing of the loft balcony. The balcony will be replaced next year so I have no concerns about damaging it further. The inverted vee apex is only 9 meters high and the ends, tied to two of the numerous trees around the yard, are about half that height. It isn't much but it works, surely better than how I returned to the hobby in 2013.

A 15 meter length of RG213 connected the FT950 temporarily located in the loft bedroom. No holes were drilled. The rotting weatherstripping and sill of the balcony door allowed just enough room for this thick cable to squeeze through (the door is also slated for replacement).

DX contacts soon followed. The only ones of note were S9YY on 30 and 40 meters and TL0A on 17. That getting through wasn't easy is good since it allows me to hone my pile-up skills.

Towers are being sited and construction has begun. I'll get into the details in a future article. For now I'll present a Google satellite view of the area of my 50 acre property that is most germane to radio use. That circle you see is an attractive stone wall lined with birch trees inside half its circumference. The fields beyond are tilled for hay by a local farmer, who I have yet to meet. Towers will reduce the tillable acreage a small amount.

A self-supporting Trylon is going up a short distance to the northeast of the house, behind the location of the future garage. I need to plant the tower before the garage excavation is begun so the concrete truck can roll up to the tower base. Trust me, you do not want to move 6 yd³ of concrete in wheelbarrows (~50 heavily-laden trips). Concrete pumps are an expensive alternative.

The LR20 150' (43 meter) tower will be placed directly east of the house and yard. I still do not know if I'll have time to get that tower planted before ground and air conditions are too cold to proceed. There are 4 excavations and reinforced concrete work for the tower, and potentially long wheelbarrow trips to place ~5 yd³ of concrete.

I did get a commercial quote to put up the tower (all labour, equipment and materials) and even with an "amateur" discount it is a quite expensive $20,000+. For some amateurs this is acceptable. Others do some of the work themselves and bring in professionals for the rest. That can be far more economical if you have the time, skills and body strength. I plan to do as much as possible myself, not excluding 100% of the project. For me the planning and execution of tower project of this size is a very interesting opportunity to learn and put all of my experience to the test. However I have been getting advice from professionals, both local and distant.

I close for now with a picture of some of the denizens of this large 50 acre property. There are apple trees, towering maples (and evidence of a century old sugar bush camp), animals and plenty of open space. It is very peaceful if a little isolated. There is lots of space to store antennas, towers and related material.

For amateur radio it has many attractions. The house though it needs extensive renovation is getting high marks from the many visitors that have passed through. Mixing house construction with tower work is difficult enough without the financial and legal glitches that have plagued both ends of the real estate transaction. All is clear now bar the hard work.

My next blog posts will get into siting the antenna farm and planting towers. There is a lot of excavation work ahead before the ground freezes. Regrettably I will not have a station for this weekend's CQ WW SSB contest, so I will not be competing for SOAB QRP #1 for a third year running.

Two Tons of Steel, and Administrivia

I've accumulated lots of stuff over the decades. Not just amateur radio stuff, of course. I am amazed how much stuff there is in my house to be moved. With my now very imminent move this has become a small nightmare. I've given or discarded 40+ years of QST and other ham magazines, sold a few household appliances I'll no longer need, and I have a list of more things to sell after I am settled in my new QTH.

Every one to two days over the past 2 weeks I transported a carload of fragile and odd-shaped stuff in my car. Yes, this included every bit of amateur radio gear I own, of which there is a lot. I even moved the 2 kilowatt power supply I built over 25 years ago for a set of amplifiers I never did get around to building. The power supply works great though, including its regulated 300 VDC screen supply for tetrodes.

The big stuff is another matter. I now have 4 towers, 2,000' of Heliax, 3 tri-band yagis, several rotators (including two prop pitch motors), a 2-element 40 meter yagi, assorted VHF yagi, over 100' of steel mast, and much much more. Almost none of it fits in a car. So I turned elsewhere for help.

One of my neighbours own a landscaping business. One evening a couple of weeks ago he showed up with a 5-ton truck and trailer, a few of his sons, his wife and several employees. Even with so many hands it was a hard job to load the towers, masts and related paraphernalia.

Two of the guys and I took care of the unloading at the new QTH. It sufficed, just barely; it was a tough job. I paid for everything of course, though at a price point better than I could otherwise accomplish.

I remember that while standing on top of the load on top of the truck (feeding sections to the guys below) close to midnight my phone rang. It was a fellow ham wondering how the move was going. So I told him!

300' and 2 tons of towers and masts at the new QTH in FN24

This has been unbelievably difficult work. Yet I'm not done. The antennas and Heliax would have to wait for another truck, which is pending as I write these words. Of the big antennas all but two of the tri-banders were knocked down to small lengths and transported in my car.

As if all this weren't enough I have more tower on order. There are only 6 weeks left to plant towers in the ground, before the risk of frost in the ground puts an end to concrete work for the winter. Towers and antennas work can continue in the cold, if I am so inclined.

Going dark, for a while

The next part of the move is more serious and will occupy me for the next week. This means no new blog post, no moderation of comments, no email and no phone calls. Aside from being busy there is as yet no internet or phone service at the new QTH.

If the blog and I seem unresponsive you'll know why.

Changes to contact info

A number of correspondents have email and phone contact information that as of now are invalid. There will no forwarding or other notification beyond this note.

Email should be sent to my call sign at rac.ca or arrl.net and no other. When I eventually reply you'll have the new direct email address. My phone number will be disclosed as necessary following email contact.

See you soon.

Two Approaches to Penalizing Contest Log Errors

The title of this article of long since it can take some description to explain a simple dilemma. Which is who to penalize when one operator in a contest QSO makes a mistake? Sounds simple, yet therein lies an interesting dilemma.

I was forcefully reminded of this when I recently received my log report (UBN) for the RDXC CW 2015, and by internet discussions of some frustrated contesters. For those who do not enter contests -- or at least do not contest very seriously -- this may be no more than a curiosity. Dedicated contesters have good reason to care.

First, a brief explanation of the two penalty schemes.

A) Penalize the operator who makes a mistake

Let's say I call and work XX9YY. I log the call and the sent exchange. The exchange is contest specific. It can as simple as a report and a zone such as in CQ WW. More complex are exchanges with serial numbers. Far more complex is the exchange in ARRL Sweepstakes, or the QTC system in WAE.

The chance for errors is greater with more complex exchanges yet even simple exchanges can create many errors by operators who become careless. For example, not really listening and just letting the logging software fill the log fields.

So if you are a K5 operating in California and I log zone 4 instead of the zone 3 you sent I see my score reduced by the erasure of the QSO and a further penalty. If I copy your call sign wrong you may never know because in S&P operating (typically for QRP contesters like myself) it is common practice not to send the other station's call. If I don't send it he can't correct my error.

That's really all there is to it. I get the penalty while the other operator in the QSO is not, assuming that he copied my call and exchange correctly.

B) Penalize both operators when one (or both) makes a mistake

In contests like RDXC it is the responsibility of both operators to correctly copy the sent call and exchange and to ensure that the other operator correctly copied their sent call sign and exchange. If either operator makes an error the QSO points are erased for both operators. A further penalty may be assessed.

It is therefore incumbent on all contest participants to transmit a clean signal and send the call sign and exchange in a manner to ensure they are correctly logged by the other operator. Ideally this results in better operating practice by everyone. Although it can also slow rates it does so for everyone.

Regrettably the ideal is not consistently achieved in practice.

Rules modify operator behaviour

Rules can improve operator behaviour but cannot entirely eliminate common problems. They can even cause new problems, perhaps ones that are unanticipated by the contest sponsors. Competitive operators want to win and will exploit the rules to maximize their results, and do so while staying within the rules. There are always ways to find advantages despite the intent of any rules.

The common theme is twofold for the competitive operator:

1. Maximize points
2. Minimize penalties

Let's look deeper at these imperatives in the context of both penalty regimes, focussing on the operator behaviours they induce. Both have pros and cons.

The majority of contests use scheme A. This engenders poor operating behaviour by a relatively small number of big guns and those offering a rare multiplier. They see every incentive to send quickly and loudly to maximize rate when running with little regard to the other operator's attempt to log the QSO accurately. After all, if the caller makes an error they are the one penalized, not the running station. Thus we see the following from some:

• Very fast CW speed (35+ wpm), or fast talking on SSB
• Infrequent identifying
• Not correcting obvious errors in the other station's copying of their call or exchange
• Distorted transmission: over-modulation or compression, chopped code elements, etc.

Some contest sponsors are taking steps against these poor behaviours, though for the most part the perpetrators get away with it. My opinion is that this is unethical operating since it often negatively impacts the score of other contest participants. Pursuit of a high score is not an acceptable excuse.

With scheme B the dynamic changes, and therefore the behaviour of contest participants. Speeds slow and identification becomes more frequent. There is an added incentive to elicit confirmation of correct copying. Distortion only slows the QSO so gain controls get dialled down.

So far so good. However it is not all roses. When doubt creeps into an operator's thoughts about whether the other station did indeed copy everything correctly there is a chance, sometimes a good chance, that they'll silently wipe the QSO. When that happens the other unsuspecting operator receives an NIL penalty (not in log). The one wiping the QSO loses the points but avoid the risk of a penalty.

All it takes is sufficient doubt (a subjective choice) to result in penalties for other participants. Unlike in scheme A this is not a matter of unethical operating, merely a fear of penalties. Whether that fear is rational is difficult to say.

Which is better?

I have no firm view on this matter. Any rule has its loopholes and downsides. The clever operator will find them and then modify their behaviour for maximum advantage. The unethical operator will only focus on their advantage and not the impact their choices have on other contest participants.

I was at first favourably disposed toward scheme B when I first learned about it. I am less sure now that I've experienced its problems. Nevertheless it is an interesting experiment that is worth wider adoption to see how it plays out in larger contests. Since tradition has great momentum I don't expect this to happen any time soon.

I suspect that one's opinion correlates well with primary operating style: run vs. S & P. Self interest is a powerful motivator. Even my own view may change as I transition from QRP to QRO contesting, and therefore more running.

Unbending Bent Tubes

When disaster strikes we often find ourselves with a pile of scrap aluminum and steel. After shedding a tear or two it is time to dive into the scrap heap and decide what can be salvaged and what must be trucked away for disposal or recycling.

A word about risk

Of course we want to reuse as much as possible, it just isn't always wise. In these matters I find it helpful to reflect on the old cliche: "if you have to ask the question...replace it." Unfortunately the less you know the more doubts you will have. Or if you thrive on risk you simply skip the question phase and jump into salvaging almost everything while prudence looks on in horror.

A little knowledge combined with a little ingenuity is perhaps best: you strive for economy yet know that there are important limits to what can be salvaged. Aluminum tubing can be expensive and is a prime candidate when an antenna turns into scrap.

The danger is that aluminum and its alloys fatigue easily when bent. Every bend weakens the metal, including the bend to return it to its original shape. Tempered alloys, including those used in aluminum tubing, weaken even more when bent. You must think very carefully whether the risk is worth it.

The general rule I use with aluminum tubing is to try and save a tube with a gradual curve and discard one with a visible kink, especially a kink that changes the cross-section from a circle to any other shape, be it an ellipse or something more extreme. The application also matters: a tube that is at the end of a yagi element or light duty boom mostly only supports itself and is more amenable to rescue.

Consider the following tube:

This is a 1.5" O.D. tempered aluminum alloy tube (most likely 6061-T6) with a 0.058" wall that telescopes with similar tubing in ⅛" steps. It comes from the boom of my old A50-6 yagi that I plan to resurrect in modern form. The bend dates to when the temporary wire antenna mast of which it was a part collapsed.

In my judgment this tube is a good candidate for saving. Even if only for the practice it is worth making an experiment of it. The replacement cost is small if the straightening attempt fails.

Tough tube

Aluminum alloy tubing of this diameter is surprisingly tough. Try to bend it over your knee and it's your knee that is more likely to bend. Some casual attempts to straighten it soon after the disaster went nowhere so I cast it aside for the time being.

When I recently took down my towers I recognized an opportunity. The 1.5" schedule 40 steel pipe coupled to the frame of the house (used as a tower guy anchor) looked perfect for what I had in mind. There are two important reasons. First, the pipe was effectively an immovable object for the force I would need to apply. Second, the I.D. of the pipe is 1.61" (the 1.5" designation is a nominal figure) into which the tube would slide in nicely and largely conform to the shape of the tube.

The second point is worth some elaboration. To straighten the tube it is necessary to apply a force greater than the tube's yield strength. Unless the tube is secured against a similarly curved surface there will be stress risers that will result in kinking or even collapse. The 1.61" I.D. is in a way even better than 1.5" I.D. since it allows a portion of the curved section of tube to be firmly couple to the pipe. That is, slide it into the pipe until you encounter resistance.

Snipe

We are not quite ready to proceed to bending. We need a way to apply the right force at the right place. Let's look at a tool for helping with that task: the snipe.

The bending force must be applied close to where the tube is secured to the pipe so that we can ensure that the only point that yields is in the vicinity of that coupling point. If we grab the tube by its end, for maximum leverage, the result will be unpredictable, and likely destructive. Yet if we hold the tube closer to the coupling point we almost certainly don't have the required body strength.

Pipe snipe

What we need is a snipe. Most often it takes the form of a long steel pipe that is placed over the handle of a tool to multiply leverage. Too often a snipe is used inappropriately (easy to do) resulting in a broken tool, broken machinery or, worse, a broken body. The approach we are going to take is more moderate and will permit good control of the force.

My snipe is another 1.5" schedule 40 steel pipe. It is long enough for the required leverage yet no so long that damage is easy to inflict on the tube. As with the fixed pipe it has a shape that reduced the risk of stress risers.

Gauging the force being applied is not obvious. If you push too hard you will feel the tube bend. You don't want that since it invariably means you've applied too much force and probably damaged the tube. If you are too careful the tube will not bend at all.

Experimentation with increasing amounts of force is required. It is necessary to inspect the tube after each push, which though tedious is mandatory.

Inspect the tube carefully: the bending will occur in the exposed area between the two pipes. Keep the pipes separated by about 6" so that the stress is distributed in a way to straighten several inches of tube at a time. Several bending actions will be required. Be sure to push exactly against the curvature. Align the tube so that the curve is exactly vertical or horizontal so that you can more easily judge the direction of applied force.

Almost straight

Start from one end of the bend and work gradually toward the other. Slide the tube further into the fixed pipe as each bend is accomplished. Check carefully after each bend to make sure the tube is straightened over that portion of the tube. When you believe you're done put a straight edge on all sides of the tube to confirm that you were successful. You'll have to decide how exact is sufficient to your use of the tube.

Almost straight

When I was done I inserted the tube back into the boom. The tube was straight but the boom was not!

I hadn't noticed before that the next telescoping tube (1.625" O.D.) also had a bend, although it is much less than that in the end tube. That will require a different setup since it will not fit the steel pipe I have on hand.

For the moment that is inconvenient so it must await a future opportunity. This is not something to rush into since use of the wrong size pipes can wreck the tube.

Final words

Bending aluminum tubes in the manner I described is risky but can be worth the attempt if the damage is within reason, as I described earlier in the article. In this case the tube is inexpensive so I was prepared to take a risk knowing I could buy a new one if I damaged it further.

For tubes in more structurally critical applications I would advise you to be safe, skip the experiment and buy a new tube. The same advice applies if you simply cannot be certain that it is safe to straighten the tube.

Then there's steel. That is a topic worth its own article. I have one planned on that subject focussing on damaged towers.