David,
I'll e-mail you privately and share because I probably screwed the whole thing up in trying to copy it. However, the good info I have gotten here did calculate out correctly and at least I have a way to work with the situation. I wish I had done what your doing and that is just take them close together. I took my General back in the 90s and way to much time passed before I decided to upgrade to Extra and not to mention I finally am getting back on the air after about eight or 10 years.
I'll be in touch.
73
Scott/N3BYY
On Jan 17, 2012, at 9:05 AM, David thurmond wrote:
> Scott,
>
> You had asked for math help in computing the resonant frequency of an
> LC circuit.
>
> Well, first off, are you sure the formula you listed is for an LC
> circuit? Looks like it might be for RC instead based on the variable
> names.
>
> Second, you have to make sure your units are correct for the L and C
> values. So either convert them both to Farads and Henries or at least
> get them both to the same order of magnitude, e.g. microFarads and
> microHenries. If you are having trouble entering scientific notation,
> just skip it and convert everything to the whole unit expressed as a
> decimal, e.g. 50 microFarads would be 0.005 Farads.
>
> You can double check your answer with this calculator, but beware that
> the answer you get is in MHz, not Hz, so you will have to convert the
> final value to whatever the question asks for:
>
> http://www.wa4dsy.net/filter/fr.html
>
> The nice thing is that the calculator does the unit conversions for
> you based on what units you pick for L and C.
>
> Now, I tried to look up the correct formula, but the blasted Extra
> Class License Manual I got from bookshare.org has the equations
> removed!! The formula from Wikipedia doesn't look the same as the one
> in the original question, and doesn't give the same answer as the
> calculator for the same L and C values. And other resources evidently
> show the equation as an image, useless for us blind folks.
>
> BTW, if anyone knows where I can get a complete HTML or text version
> of the Extra Class License Manual, please let me know, as I will be
> beginning my studies for that in a couple of weeks, after I finish up
> my General class test.
>
> Scott, please email me privately to discuss this question further if
> you wish. I really want to know what the formula is and what the
> answer is! I spent perhaps an hour looking for the right one, and not
> knowing is going to bug me.
>
> 73,
>
> David Thurmond, KK4ADV
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