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Thursday, December 1, 2016

Is your SWR 1:1, “one to one,” or simply 1?

KB6NU-TECH-guideA question came up on the ham_instructor mailing list this morning with regard to the next update of the Technician Class question pool. Bob, K0NR, wrote:

While reviewing the Element 2 (Technician) question pool, I am reminded that the question pool SWR readings are referred to as “10 to 1”, “5 to 1” and “1 to 1”, etc. I suppose this emphasizes the “ratio” nature of SWR, but it just sounds old school to me—kind of like saying “kilocycles per second.” I just refer to SWR readings as a single number (e.g., 10, 5 or 1). What do you folks think?

Being a freelance writer and editor, I found this to be an interesting question. There are lots of these kinds of grammatical questions, especially when it comes to technical writing. Normally, we just write or say things how we learned them, whether they’re technically correct or not. In this case, I guess that I’d have to say that I still think of SWR in terms of “<some number> to 1” and  normally write it as “x:1.”

I next did a quick Google search for “SWR specification.” The results were mixed. For example, the National Instruments Web page, “Understanding Key RF Switch Specifications” simply gives the VSWR as a number, but Anritsu’s “Understanding Cable & Antenna Analysis” gives an example as “1.2:1.” There were numerous other examples of both forms, so while the search was interesting, it didn’t really yield a definitive answer. I guess that’s true of most Google searches, though. 🙂

Another thing that I found interesting in researching this is that the notation we use—1:1, 2:1, etc.—is called odds notation. Apparently, it’s still used in betting, but I can’t think of another instance in which this notation is used in a technical context.

I asked Steve Ford, WB8IMY, the chief editor of QST, about this, and he said:

For QST, our style is to express SWR in mathematical ratio notation such as “2:1,” never as “2 to 1.”

Ward Silver, N0AX, who edits the license manuals and the Handbook for the ARRL, also replied:

Speaking from experience with the Question Pool Committee, they do not like using equations or symbols in the questions or answers.  That includes “:” and they substitute text for it.  This is an old habit from the days when text files had to be of the lowest-common-denominator so that everyone could read or print them.

My suggestion is to submit a request to replace “2 to 1” with “2:1” or just “2” so that the question pool is brought into compliance with current practices.

I’m siding with N0AX and will suggest that, at the very least, they replace the “x to x” nomenclature. I’m leaning towards asking them to replace it with the odds notation, i.e. 1:1, 2:1, etc., if only because that’s the QST style. I’m not 100% sure about that second thought, though, so I’d like to hear what you think.

The post Is your SWR 1:1, “one to one,” or simply 1? appeared first on KB6NU’s Ham Radio Blog.

from Mix ID 8212326

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