# Want to make sure

Discussion in 'The Okie Corral' started by rrog, Aug 9, 2007.

1. ### rrog

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I'm studying for the general license. I've got the ARRL General Class License Manual, 6th edition. If you've got that one, the question I'm referring to is G1A05, on page 11-2. The question is:

Which of the following frequencies is in the General Class portion of the 40 meter band?
A. 7.250 MHz
B. 7.500 MHz
C. 40.200 MHz
D. 40.500 MHz

It lists the correct answer as "A." After the answer, it refers the reader to page 3-5. On that page, it says you can convert frequencies to wavelength in meters by dividing 300 by whatever the frequency is. (Ex. 300/f=wavelength in meters.) If you divide 300 by 7.500 MHz, you get 40. If you divide 300 by 7.25 MHz (which is listed as the correct answer), you get 41.38. If dividing by 7.500 MHz gets 40, I don't understand why "A" is listed as the correct answer. So my question is, is this correct or a typo? I'm willing to accept that it's just one of those things that doesn't compute exactly, but I'm wanting to make sure.

Thanks in advance for the clarification on this,

rrog

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3. ### JBlitzenGuest

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40 meters is just nomenclature. The actual frequency and wavelength limits are dictated by availability of the spectrum. The best the FCC can do is to give us spectrum "around" the given range, which is quite close enough for propagation purposes.

Never go by the /300 trick to determine exact frequency allocation; always refer to a recent chart or table, otherwise you risk running outside of the permitted range.

http://www.arrl.org/FandES/field/regulations/bands.html

has nice printable charts:

Incidentally, the frequency ranges are a pain in the ass to learn in their entirety and only account for one or two questions on the test; after weeks of review I finally gave up and focused on other areas of study and passed just fine. On the other hand, they will be the knowledge you use most when using an HF radio, so once you have a setup in place, you'll get to know your favorite bands by heart.

4. ### rrog

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Thanks for the replies. You're right and you've confirmed my suspicions. The formula is merely a guide, not a hard and fast rule. I guess it's just one of those things I've got to learn. And it's my guess there's probably going to be more of these too.

Thanks again,
rrog

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