When I took the tests back in 81, Dick Bash came out with a method to figure 
out how to perform the derrivations of the formulas so that made things 
easy.  I waltzed through the advanced and extra theory in one day and had to 
retake the code test because my certificate had expired and I ended up acing 
that one because they had a mistake in their answer key and I had 100% copy 
in Braille in front of me.  73- pat kk3f
----- Original Message ----- 
From: "Mike Cozzolino" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, January 18, 2012 12:19 PM
Subject: Re: Math Help


> hi howard, yes no conversion to farads and henries.  much easier, and
> it works.  i don't remember where i found it, but i have used it for
> years.  after when you are taking a test, use the easiest formula
> possible.  when doing all the conversion stuff its easy to make a
> mistake.  i remember when i took all my fcc exams i took them at the
> fcc office and they read the exam to me and i had to do the math in
> my head, no calculators were allowed back in those days.  take it
> easy, c u mike w6quv
>
>
>
> At 08:43 AM 1/18/2012, you wrote:
>>Mike,
>>
>>I like your formula, it is easier to work with, however, for it to work so
>>the answer comes out in megahertz, one must realize that the  L needs to 
>>be
>>in micro henrys and the C in pico farads.
>>
>>See, with all this discussion, I even learned something.
>>
>>  73's
>>
>>Howard #3
>>
>>----- Original Message -----
>>From: "Mike Cozzolino" <[log in to unmask]>
>>To: <[log in to unmask]>
>>Sent: Wednesday, January 18, 2012 10:24 AM
>>Subject: Re: Math Help
>>
>>
>> > hi david, i read through both of your postings, and the formula i
>> > gave scott is very short and gives you the same answer.  try this out
>> > and see if it works for you.  the formula is: f=159 over the sqrt of
>> > l times c.  where the c is in picosarads and the l is in
>> > microhenries.  so 50 times 200 = 10,000 the sqrt of 10,000 is
>> > 100.  now take 159 devided by 100 and you get 1.59 mhz.  a lot
>> > simpler and no conversion.  try it out and see that it works.  also
>> > remember that when you are talking about inductance and the symbol
>> > for microhenry is uh and the symbol mh is millihenry.  and you have
>> > farads then microfarads then nanofarads then picofarads.  take care,
>> > c u mike w6quv
>> >
>> >
>> >
>> > At 05:29 AM 1/18/2012, you wrote:
>> >>All,
>> >>
>> >>Sorry for my previous post, I previously stated that 1 picofarad = 1 x
>> >>10 ^ -9 Farad, which is why my calculation was wrong.  I also screwed
>> >>up entering the units on the calculator, so I should have
>> >>double-checked my work!  I believe this is correct, however:
>> >>
>> >>The formula is:
>> >>
>> >>Resonant Frequency (Hz) = 1 / (2pi * sqrt(L C)
>> >>
>> >>where L is in Henries and C is in Farads.  So, in your example:
>> >>
>> >>1.  Convert 50 microHenries to Henries, 1 microHenry = 1 x 10^-6
>> >>Henries, so 50 microHenries = 5.0 x 10^-5 Henries.
>> >>2.  Convert 200 picofarads to Farads.  1 picofarad = 1 x 10^-12 farads,
>> >>so 200 picofarads = 2 x 10 ^ -10 Farads.
>> >>3.  Now, plug into the formula:
>> >>F = 1 / (2pi * sqrt (5 x 10^-5 times 2 x 10 ^ -10)
>> >>= 1 / 2pi * 1 x 10^-7
>> >>=1591557 Hz
>> >>
>> >>Hopefully this is correct now, and hopefully I did more than just
>> >>muddy up the waters beyond all hope!  My apologies!
>> >>
>> >>So you can see, the worst part of this problem is getting the units
>> >>correct, at least for me.
>> >>
>> >>73,
>> >>
>> >>David Thurmond, KK4ADV
>