Megacycles & Megahertz

Discussion in 'General Technical Questions and Answers' started by K9KXW, Jun 30, 2007.

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  1. K9KXW

    K9KXW Ham Member QRZ Page

    Good Day Everyone, I've read a few books and a lot of QST articles.

    In the older books and K2TQN's "Old Radio" department and the "75, 50 and 25 Years Ago" department of QST, I notice that they refer to Megacycles "Mc" instead of Megahertz "MHz".

    I'm curious as to why the change in the name and when that change came about.

    I know that "Hertz" came from  a gentleman I believe from Germany (Heinrich Hertz) if that is correct, but not sure how or why.

    I don't expect a direct answer, but maybe a website that would give me some background on the subject.  [​IMG]  

    Thanks and 73

    Edited for misspelled name.  [​IMG]
  2. K3RRR

    K3RRR Guest

  3. AB1GA

    AB1GA Ham Member QRZ Page

    Every now an then the international standards guys get together and make some changes so they can justify the rich food they eat at working meetings. [​IMG] I think 1968 was the release of the SI system of units.

    I think the change from cps to Hz happened in the late 60's because I vividly remember a QST article making fun of the change.

    Rod Newkirk, W9BRD, was writing the "How's DX" column, and he would regularly have a report on the latest DXHPDS (DX Hoggery and Poetry Depreciation Society) meeting. One year there was a bunch of stuff about historians writing about hertzical history, the pain of riding a bihertz, and the pope issuing enhertzicals.

    These were my father's QSTs, and he stopped getting them about '68 or '69. At that time the standards boys were busy releasing revised temperature scales and the like, so the timing fits.

    Looking at the modern units, it seems the standardizers wanted to name all of the units after famous scientists, thus the changes. Some of the ones I remember:

    cycles per second -> Hertz, after Heinrich Hertz
    mho -> Siemens, after Werner Siemens
    wavenumber -> Kayser

    These were direct name changes. At the same time we were encouraged to use Joules instead of calories, Watts instead of horsepower and Pascals instead of psi.

    Oddly enough, I don't think they gave the optical units special names.
  4. K9FV

    K9FV Ham Member QRZ Page

    It actually does say "When" - 1960. I guess that's about right, it was in my later high school yrs when I remember the name change....

  5. N3EF

    N3EF Ham Member QRZ Page

    Near the top of this article, it says 1965. There are some humurous conversion charts around as well. Here's one over on Eham.

    Eric N3EF
  6. K9KXW

    K9KXW Ham Member QRZ Page

    Thanks Guys for the info and Bob thanks for the link.

    I didn't realize that the change came about that late "1960", I was thinking somewhere in the 1930's or so.

    I had Hertz first name misspelled, but fixed it.

    Thanks Guys and 73
  7. K9FV

    K9FV Ham Member QRZ Page

    I sorta was thinking 1960 was early for the name change, but since it was "written on the internet" I figured I was remembering wrong - the time of 1965 almost seems too late also... Heck if I know when the name change took place, but sometime in the early '60's I do think.

  8. K7MH

    K7MH Ham Member QRZ Page

    Interesting topic!
    I had no significant interest in radio until 1969 and I have always been a "cycles" guy. If I am talking about it, I will use cycles. If I am writing something about it I will use Hertz.
  9. W9GB

    W9GB Ham Member QRZ Page

    When I started reading in late 1960s and early 1970s, only the latest books would use Hertz.  The vast majority used cycles per second (which are actually easier to explain to a Novice or for a begineer to comprehend).

    In fact, I think my first FCC exams were all in cycles per second, as well, in early 1970s.

  10. AG3Y

    AG3Y Guest

    To put it very briefly, (and probably echo the Wiki article )  "Hertz" took the place of the term "cycles per second".  The term "cycles" has always been used, and commonly understood as "cycles PER SECOND", but NOT emphatically stated as such.   Therefore 60 cycle AC could have meant 60 cycles per second, minute, hour, day. . . . you get the idea !   So they decided to state catagorically that "Hertz" stood for so many cycles PER SECOND !  

    A bit silly, I believe!   But PC anyway !    73, Jim
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