What kind of calculator?

Discussion in 'Becoming a Ham - Q&A' started by K6JK, Apr 28, 2010.

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  1. K6JK

    K6JK Ham Member QRZ Page

    I'm planning on sitting for the tech and general tests this weekend and want to bring a calculator, but I'm guessing neither my trusty HP-48GX nor my HP-28S will be allowed. I've seen references to "non-programmable scientific calculators" and ones whose memories have been cleared. Can someone clear this up for me? I've searched but haven't found anything - I'd prefer to try and stick with an RPN calculator if I have to buy a new one. :)

    (And I'm assuming the one on my iPhone is right out.)
     
  2. AB1GA

    AB1GA Ham Member QRZ Page


    I brought my HP-15C to my test session and got no hassle. Since the team is really only interested in making sure you have no "cheat sheet" info in memory, the use of the "Clear All" or "Memory Reset" functionality should keep things smooth.

    But the more I think about it, the more certain I am that I never actually USED the calculator during the test. The only answers that can't be calculated using a graphite-doped four-banger are the ones involving trig functions, and even then a bit of algebra and trig knowledge along with the ability to make a reasonable approximation takes you the rest of the way.

    73 and good luck,
     
  3. K0CMH

    K0CMH Ham Member QRZ Page

    You will find no written rule specific to specific calculators.

    The concept is that the VEs do not want any means of cheating. Programable calculators often have the capacity to store information that could be the answers to test questions.

    It depends on the particular VE group as to how they apply this concept. Some may simply say "no calculators that can store memory", others may simply say, "no programable calculators". Others may allow any calculator, provided they can witness the clearing of any possible memory that could store answers to questions.

    I suggest you contact the person in charge of your VE group and ask what their policy is on calculators.

    I took one and did use if for some very simple calculations, but I took my simplest one that only had the +M, -M and recall M keys. It did have a number of functions (trig, staistics, etc.). It had no programing features at all. The VE took one quick look at it and said "OK".
     
  4. N0IU

    N0IU Ham Member QRZ Page

    First of all, you are most likely going to have to shut your phone off, not matter what kind it is. And since it is a "smart phone", you could theoretically look up the answer on the web so it might be best to no bring it in with you or not let anyone know you have it.

    But honestly, you probably won't even need a calculator at all.

    Good luck!
     
  5. KD7MSC

    KD7MSC Ham Member QRZ Page

    Leave the calculator at home and use a pencil and scratch paper. Not much math on the tests anymore.

    73 and good luck with your tests.
     
  6. K6JK

    K6JK Ham Member QRZ Page

    Well, going through the questions in the ARRL book there is more math than I thought. The classes in college that didn't allow calculators usually had problems that evaluated to 0 or 1 or -1. There were questions in the test pool like:

    G5B08 (D)
    What is the peak-to-peak voltage of a sine wave that has an RMS voltage of 120 volts?
    A. 84.8 volts
    B. 169.7 volts
    C. 240.0 volts
    D. 339.4 volts

    I really don't want to spend the time doing the arithmetic for that longhand. I've got better things to do. :)

    My concern about the HP48 is that it has an equation library that has many EE equations in it. And since that would allow me to cheat it will have to stay at home. I'll go pick up a cheapie calculator and save the might HP48 for real work.
     
  7. AB1GA

    AB1GA Ham Member QRZ Page


    No need to use a pencil, even.

    Peak voltage of sine wave is square root of two times the rms voltage. You have to know that and the that the square root of two is about 1.4.

    Peak voltage is 120 times 1.4, or 12 times 14.
    12 * 14 = (13 - 1) * (13 + 1) = 13 * 13 - 1 needs a bit of algebra here
    13 * 13 - 1 = 169 - 1 = 168 need to know squares of numbers

    Pk-pk voltage is double the peak voltage, or 169 * 2 = 338.

    And the winner is: D


    Actually, it's even easier than that, here's a sanity check:
    The peak voltage is significantly bigger than the rms voltage.
    The peak-to-peak voltage is double the peak voltage.
    The pk-pk voltage is significantly greater than double the rms voltage.
    The pk-pk voltage is significantly greater than 240.
    Only one answer fits the bill.


    Think about the problem before doing the math! And again, good luck!
     
  8. KC7DRI

    KC7DRI Ham Member QRZ Page

    As a general rule of thumb, take the lowest end calculator you would need to do the calculations, although most can be answered correctly with a quick educated guess as the other 3 answers tend to be way off the mark.

    For my Tech & General tests I was able to get by with an old (early 80's vintage solar) "Computer Math Calc" as the calculator shows on the face. It has some of the most commonly used functions of a scientific without being one. I found I needed a full scientific one for the Extra test a few years ago, and since mine was dead, I just picked up one of the cheap ($10) scientific ones to replace it. The funny thing about this one was that I spent a lot of time learning how the memories actually worked so I could demonstrate they were cleared. There was not an actual clear operation. Storing a value of 0 in a memory was how it was "cleared".
     
  9. K7JEM

    K7JEM Ham Member QRZ Page

    Dale has the right answer. On the test, only one answer will be even close. If you know the formula for RMS to P to P conversion, then you're set. If you don't know the formula (or conversion multiplier), then what good is a calculator going to do?

    Since P to P is about 2.8 times the RMS value, it is easy to see that only one answer is even close. The next closest answer is 2 times the RMS value.

    Joe
     
  10. KF7AYS

    KF7AYS Ham Member QRZ Page

    If you need a calculator to pass the Tech and General exams, you really need to go back to school.

    No calculator needed.
     
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