Knowing the formulas for conversion means that you can do them in your head.
The arithmetic is easy.
Actually, the arithmetic is trivial if you allow a slight error in your result.
Formula for going from F degrees to C degrees is:
C = 5/9 * (F - 32)
Or, five-ninths of result of subtracting 32 from F degree reading. But, 5/9th
is close to 5/10ths for rough, in the head, calculations and 5/10ths is 1/2 or
one-half.
So, to convert degrees F to degrees C you do the following: subtract 32 then
divide the result by 2.
Easy to do in your head quickly even while carrying on a QSO with someone in
Celsius land. Example, your outdoor temperature is 85 degrees F (meaning, you
don't live in the Seattle area) so you subtract 32 to get 53 and divide by 2
which is 27.5 degrees. The actual value is 5/9th instead of 1/2 (5/10ths) so
the correct C reading of 85 degrees F is: 29.44 (and, not many of us can feel
the difference in temp of just 2 degrees).
You can even get used to the idea of adding in a fudge factor due to the error
in the calculation that might range from 1 to 3 degrees depending on the range
of the F value. The actual error is close 6 percent (that is, result is ~6
percent too small using this trick) so just remember the 6 percent fudge
factor).
For C to F just do the opposite: double your C temp value and add 32.
73, phil
On Jun 22, 2014, at 7:30 AM, Jim Miller <jimmil...@stl-online.net> wrote:
> I understand the metric system. I have to convert everything. My mind has
> been in OUR system for 70 years and doesn't visualize anything until I
> convert it. Additional comments withheld .
>
> I don't force you to do anything my way so why do you try to force me to do
> things your way?
>
> Too old for this xxxx.
> 73, Jim KG0KP
>
> -----Original Message-----
> From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Charlie
> T, K3ICH
> Sent: Sunday, June 22, 2014 6:28 AM
> To: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] Temperature Sensors
>
> Personally, I can't WAIT until we endorse the metric system. Then we'll only
> have ten months so we can completely eliminate those nasty January's and
> February's.
>
> Chas
>
>
> ----- Original Message -----
> From: "Mark via Elecraft" <elecraft@mailman.qth.net>
> To: <elecraft@mailman.qth.net>
> Sent: Saturday, June 21, 2014 11:37 PM
> Subject: Re: [Elecraft] Temperature Sensors
>
>
>> Don said: “Yes, but you have to do a bit of math.”
>>
>>
>>
>>
>> …or use one of the most useful pieces of software ever written (for an
>> engineer, anyway), Convert (http://joshmadison.com/). I used it
>> throughout my career which required skills in both metric and imperial
>> systems. Like Morse Code or learning a new language, it gets easy after
>> you do it for a while, but usually conversion isn’t really necessary. All
>> modern electronic components are spec’d in metric. Electronic power and
>> temperatures limits have always been in metric units, even for old tubes,
>> so it makes sense that Elecraft chose to display Deg. C.
>>
>>
>> Keeping a few key temperatures in mind really helps. Water freezes at 0
>> deg. C, 20 deg. C is about room temperature, 70 deg. C is uncomfortable to
>> touch, and water boils at 100 deg. C and will definitely hurt to touch.
>> Write this down, keep it in front of you. Get familiar with a few
>> component spec sheets for some of the components in your radio whose
>> temperatures are displayed, and you will soon start thinking in “degrees
>> Celsius”.
>>
>>
>> Learn, learn, learn. It will keep you young!
>>
>>
>>
>>
>>
>> Regards,
>>
>>
>> Mark
>> ars: KE6BB
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>>
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