Adding a bunch to the confusion :
Why antenna or baloon constructors say ;
Max power ( as an example )
ssb/1500 w
cw/750 w
rtty/500 w
Just rember something ( 1950 ) like first derivation and the second
derivation of a sine........
Why two-tone is used when measuring .....?
Jos on4kj
----- Original Message -----
From: "Bill Fuqua" <wlfuqu00@uky.edu>
To: <amps@contesting.com>
Sent: Thursday, November 07, 2002 8:41 PM
Subject: [Amps] RMS-PEP & 2x8877
> When this came back the columns were messed up. I hope this is better.
>
> OK enough...
> RMS has one meaning, definition or procedure if you want to call it that.
> R take square root
> of
> M the average (mean)
> of
> S the square of a number of data points
> It may look complicated as an equation or an integral expression
(calculus)
> but it is SIMPLE!!!!
> For example...
>
> Take one cycle of a 1 volt peak sine wave and divide into at least 8
> equally spaced points starting at zero degrees.
> Calculate instantaneous voltage, voltage squared and power into 50 ohms
> load at each point.
> Do not use 360 degrees because it is the same point as 0 degrees. You may
> do this for any number
> of full cycles and you may want to do this on a spread sheet for each
> degree (ie 360 points) or what ever.
> Phase Voltage Voltage Squared Power into 50
ohms
> Degrees
Watts
> 0 0 0
> 0
> 45 .7071 .5
> .01
> 90 1 1
> .02
> 135 .7071 .5
> .01
> 180 0 0
> 0
> 225 -.7071 .5
> .01
> 270 -1 1
> .02
> 335 -.7071
> . 5 .01
> totals 0 4
> .08
>
> average of
> totals 0 .5 .01
>
> Square Root of average of
> the voltage squared .7071
>
> The RMS value of the signal is .7071 times the peak (1 Volt)= .7071 volts
> GEE look at above bold and underlined.
> What is the power of this signal into a 50 ohm load?
> .7071 volts squared divided by 50 ohms= .01 watts Look again above at the
> average power bold.
> It is all very consistent with calculations using RMS voltage or Current
> and resistance and power.
> Now what happens when we take RMS of the Power??
>
> Phase Voltage Voltage Squared Power into 50
> ohms Power Squared
> Watts
> 0 0 0 0
> 0
> 45 .7071 .5 .01
> .0001
> 90 1 1 .02
> .0004
> 135 .7071 .5 .01
> .0001
> 180 0 0 0
> 0
> 225 -.7071 .5 .01
> .0001
> 270 -1 1 .02
> .0004
> 335 -.7071 .5 .01
> .0001
> totals 0 4
.08
> .001
>
> average of
> totals 0 .5
.01
> .00015
>
> Square Root
> of
> average 0 .7071
> 0.01225 RMS power ?????
> OK above is your RMS power for what ever good it is....
> And it does not relate to any of the other numbers you may use such as
> voltage, current. resistance or power. But does give you 22.5% bigger
> number in this example.
> 73
> Bill wa4lav
>
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