2019-07-03

Demise of SAL-30

I concluded my post last year about my experiences with the Array Solutions SAL-30 with  the following comment:

10. I expect to dismantle the whole expensive mistake over the summer, and add the aluminium and wire to my stash of spare bits and pieces -- while pondering what to do to really improve 160m reception for next winter.

What I actually did was to fiddle with it and try it for a second season (winter 2018-2019).

The experience over the second season was not substantively different from the experience in the first season. Oddly, after some tweaking, the antenna consistently outperformed my inv vee on 40m -- that is, a band on which it's not really supposed to perform very well. On 80m, there were perhaps a couple of occasions when it was a marginal improvement on my 80m inv vee, although I don't believe that it ever allowed me to complete a QSO that I would have been unable to complete without the antenna. On 160m, which is the band where I really need help hearing, there was not a single occasion when it outperformed my 160m inv vee; indeed, the majority of the DX stations that I worked on the inv vee were completely inaudible on the SAL-30.

Unsure what to do next, I've left the antenna in place over the summer... until last night. For no obvious reason (we had no notable wind overnight; indeed, July is the one month of the year in which substantial winds have never been recorded in this area), this morning the SAL-30 was in pieces on the ground.

Inspecting the wreckage, three separate failures are evident, although I cannot be sure in what order they occurred to lead to the antenna being in pieces on the ground.

1. One of the guy lines was frayed through. This appears to be a result of Array Solutions using line that is insufficiently resistant to UV-caused deterioration. This is the third or fourth failure of this kind that has occurred in the time (roughly 18 months) that the antenna has been in place.

2. The internal metal sleeve (called a coupling in the manual) between the two long vertical sections was sheared completely through. It's hard to see how this could have been the initial cause of failure: it's not at all obvious how the coupling could have failed absent substantial sideways force, which presumably occurred only because of some other failure. Nevertheless, the fact that the sleeve is capable of failure in such a complete manner suggests that the part used was insufficiently robust for its intended purpose.

3. The internal fibreglass sleeve (also called a coupling) had lost all integrity and was reduced to little more than lengths of stringy material with no strength whatsoever. Clearly, this part was simply unfit for purpose and was reduced to uselessness by either UV or some other weathering-related attack. In this state, it provided no sideways support to the lengths of metal that surrounded it.

To the extent that I can be bothered to theorise, it seems likely that the fibreglass sleeve had lost any useful purpose; a UV-weakened guying line then failed simply due to deterioration in the summer sun; this placed a (rather minor, but apparently sufficient) sideways stress on the mast; because the fibreglass internal sleeve was performing no useful function, the upper of the two pieces of tubing that were supposed to be held in place by the fibreglass sleeve moved sideways, so that it was no longer supported by the lower piece of tubing; that created enough stress higher in the antenna for the metal sleeve at the higher joint to shear through, and the whole thing collapsed.

In any case, and whatever the cause, the antenna underwent complete physical failure in benign weather after only eighteen months.

The words "good riddance" come to mind, although of course I, like anyone else, am unhappy at having made a $1,000 mistake (I see that they are now charging in excess of$1,200 for the antenna; you can imagine my advice).