[ARC5] Audio power output - 10 meter BC-454

[D C _Mac_ Macdonald]

And, IIRC, peak-to-peak voltage on the sign 
wave is ~ 2.828 times the Erms. Ergo, the
Erms would be ~ 12.38 V (35 / 2.828). 
 
Therefore: 
 
Erms = ~ 153.17 / 500 = ~ .306W (306 mW). 
 
Nothing wrong with Neil's calculations. 
 
* * * * * * * * * * * 
* 73 - Mac, K2GKK/5 * 
* (Since 30 Nov 53) * 
* k2gkk at hotmail.com * 
* Oklahoma City, OK * 
* USAF & FAA (Ret.) * 
* * * * * * * * * * * 
 
 
 


> From: brianclarke01 at optusnet.com.au
> To: kgordon2006 at frontier.com
> Date: Sun, 17 Feb 2013 12:07:44 +1100
> CC: arc5 at mailman.qth.net
> Subject: Re: [ARC5] Audio power output - 10 meter BC-454
> 
> Sorry Ken,
> 
> You have slightly misread Neil's info.
> 
> The correct formula for power is (Erms)^2 / R.
> For a sine wave, Epeak = 1.414 Erms.
> So, (Erms)^2 = (Epeak)^2 / 2, and therefore, P = (Epeak)^2 / 2R.
> 
> 73 de Brian, VK2GCE.
> 
> On Sunday, February 17, 2013 11:23 AM, you said:
> 
> 
> > On 17 Feb 2013 at 13:07, Neil wrote:
> >
> >> I make it a shade over 300 mW RMS.
> >>
> >> 17.5 V peak x 0.707 to get the RMS voltage (12.37).
> >>
> >> E^2is 12.37 x 12.37= 153.02
> >>
> >> E^2/R = 153.02 / 500 = 306 mW
> >>
> >> 73 de Neil ZL1ANM
> >
> > Oh. So I am still wrong: P-P = RMS * sqrt2, whereas PEAK is 1/2 P-P.
> >
> > OK. Your result actually makes more sense, since the original power output 
> > rating for the BC-
> > 454 was supposed to be 300 mW.
> >
> > So the correct formula is E(peak)^2/R=P, and not E(p-p)^2/R
> >
> > Even so, it is still plenty loud enough for speaker output. I am using a 
> > Radio Shack 8 ohm CB
> > speaker with a 500:8 ohm transformer in it, so the impedance of the result 
> > is 500 ohms
> > average...,at least at some frequency in the range...
> >
> > Ken W7EKB