[Amps] RMS VS Peak VS Average power and the Bird 43 wattmeter

Dennis12Amplify@aol.com Dennis12Amplify at aol.com
Mon Mar 28 16:12:25 EST 2005


For the EXPERTS.....,
 
 I have a question which I believe will combign the two most  interesting and 
informative threads we have had going here on the reflector  for quite some 
time.
 
 Why is it that a Bird 43 with a calibrated peak reading kit only  reads 
THREE times the power for a peak reading of a 100% modulated AM  waveform, instead 
of FOUR times the power as the textbooks all say it  should?
 
 Is it because the 43 is responding to a Half wave  rectified signal but 
'calibrated' to read as though it was responding to  something else?
 
 I believe I have an answer, and it is directly related to both  threads, but 
I was hoping for some open discussion of the subject to see where  it goes, 
and if it goes in the direction of my solution or not...
 
 Hint: It is a mathematical relationship between the average response  of the 
43's analog meter movement and the FCC's definition of power  output.
 
Regards,
 
Dennis O.
 
 
 
It is surely the best thread we have seen on this reflector in a long long  
time. Very comprehensive, informative and lots of fun to  follow.

Thanks to all,
Alek. VK6APK

At 08:33 PM 27/03/2005,  David Kirkby wrote:
>John and Mary Powell wrote in a different  thread:
>
> >Is there a body of opinion out there that considers  the above subject 
> has gone on far too long, or got out of hand. To me  it appears as if 
> academic intransigence has got in the way of the  Reflector dealing with 
> it's core business. I noted an earlier plea for  an end to of 
> this  uninteresting topic, which evolved from a  simple enquiry as to 
> accuracy of the Bird 43 Wattmeter.
>  >
> >Cheers
> >John Powell.  ZL1BHQ



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