Timeline for Amateur radio practice exam question
Current License: CC BY-SA 4.0
17 events
| when toggle format | what | by | license | comment | |
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| Mar 17 at 1:29 | comment | added | Bogdan | Many people have posted mean comments for a legitimate question. Glad to see that one answer and one comment have provided a polite and valid answer. Need to mention that to answer correctly the above question you need to know the exact frequencies as the band name is approximating the frequencies | |
| Dec 4, 2018 at 8:04 | history | edited | Glenn W9IQ | CC BY-SA 4.0 |
Corrected units
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| Nov 14, 2018 at 8:37 | review | Suggested edits | |||
| Nov 14, 2018 at 9:20 | |||||
| Nov 14, 2018 at 8:35 | history | edited | winny | CC BY-SA 4.0 |
added 17 characters in body
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| Nov 8, 2018 at 18:59 | vote | accept | Mohammad Ali | ||
| Nov 8, 2018 at 18:59 | vote | accept | Mohammad Ali | ||
| Nov 8, 2018 at 18:59 | |||||
| Nov 8, 2018 at 18:58 | answer | added | Peter Bennett | timeline score: 9 | |
| Nov 8, 2018 at 18:54 | comment | added | Mohammad Ali | @PeterBennett I didn’t take into account the band, I simply did 300meter=1mhz to solve for frequency but if you, write you comment as a solution I will Mark it as correct | |
| Nov 8, 2018 at 18:47 | comment | added | Peter Bennett | The 15 metre band is 21 - 21.45 MHz, so the third harmonic will be above 63 MHz - too high. 10 Metres is 28 - 29 MHz, so the second harmonic will be 56 - 58 MHz - looks like B is the right answer. (where did the 20 Hz and 30 Hz come from?) | |
| Nov 8, 2018 at 17:19 | comment | added | Marcus Müller | About the possibility of it being a bandwidth rather than a tone: nope, none of the answer options include that option, so this must be about a single tone. | |
| Nov 8, 2018 at 17:18 | comment | added | Marcus Müller | I fully agree this is a stupid question, but if your frequency control is not reliably with 3 MHz (capitalization is important, as M = mega = 1 million and m = milli = 1/1000) of 57 MHz, that's a frequency error of more than 5%: If your oscillator is that unreliable, no matter what you do with it, turn it of, and repair or replace it. No discussions: that is a broken oscillator. | |
| Nov 8, 2018 at 17:15 | comment | added | Mohammad Ali | @MarcusMüller it’s in the range of 54-60 though and that 57 MHz transmission could quite possibly have a bandwidth of 6mhz assuming it utilized frequency modulation+ you have to assume the transmitters frequency control isn’t perfect | |
| Nov 8, 2018 at 17:15 | review | Close votes | |||
| Nov 14, 2018 at 8:35 | |||||
| Nov 8, 2018 at 17:13 | comment | added | Marcus Müller | Also, let me do the quick math: $$ f=\frac c\lambda = \frac{3\cdot 10^8 \frac{\text m}{\text s}}{15\,\text m }= 20\,\text{MHz,} $$ so no matter which harmonics you count, 57 MHz is not a multiple of 20 MHz and B and D are both equally wrong. | |
| Nov 8, 2018 at 17:08 | comment | added | Marcus Müller | "harmonics" are sometimes counted differently; in some contexts (not really in this, but whatever, ham radio exam questions are full of incorrect and / or vague formulations in many countries of this earth), only the odd harmonics count; in some I could imagine you'd only count the even harmonics. I don't know – maybe this is one of these cases. | |
| Nov 8, 2018 at 16:56 | comment | added | Marcus Müller | I'm voting to close this question as off-topic because it's not a general EE question, it might be better off at ham.stackexchange.com. | |
| Nov 8, 2018 at 16:54 | history | asked | Mohammad Ali | CC BY-SA 4.0 |