[R-390] Slide rule calculations

[w9ya]

Hey Bill and the gang;

Well while the way most people are taught to use a slide rule you can go
between 3 to 4 places of accuracy; There IS a way to increase that at least
one order of magnitude for most calculations !! And a larger slide rule also
helps.

Further this problem can be calculated without regard to the first several
levels of magnitude anyways.

Bob
w9ya

On Thu, Dec 4, 2008 at 6:19 PM, Bill Hawkins <bill at iaxs.net> wrote:

> George,
>
> You can't do it with a slide rule, because you can't read it to one
> part in a thousand. For ten times the cost, you might be able to
> read it to one part in 10,000 with a magnifier.
>
> Four beats per second means your generator is 4 Hz either above or
> below WWV's 2.5 MHz. On the plus side, that's 2.500004. Multiply
> that by 4 and get 10.000016 MHz, or 1.6 parts in 10 to the sixth
> power (which is 1 millionth or 1E-6, where E is exponent of ten).
> You'll get the same answer if you divide 4 by 2.5, but it'll take
> longer.
>
> So your accuracy is 1.6E-6 or 1.6E-4 percent, or 0.00016%. This is
> very good for something set by a dial. But you get 2.5000005 or
> 2.5E-7 when you move 10 Hz on the dial. You were only off 4 Hz
> before, so I'd guess that you went from being below to being above,
> and made a tiny error in setting the dial.
>
> WWV on a bad propagation day is good to 1E-7.
>
> Was that what you're looking for?
>
> Bill Hawkins
>
>
> -----Original Message-----
> From: george stringe
> Sent: Thursday, December 04, 2008 12:47 PM
>
> OK so here is a test for all the slide rule junkies: I have my Wavetek
> sig gen all warmed up and my BA Hallicrafter SX-71 tuned to WWV at
> 2.5Mhz.
> When the generator is set at  2.50000 Mhz, I am guessing that I get 4
> beats/second,  if I set the gen at 2.50001, I get 2 seconds per beat.
> So, what is my generator accuracy percentage?
>
>
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