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

[TexasRF@aol.com]

Unfortunately my Bird 43 has no peak reading option. It did have the option  
once upon a time but I got tired of it eating 9v batteries and removed it.
 
I have also "discovered" that the screen voltage stability has a pretty  
large effect on power output. Just as the plate voltage can sag under load, so  
can the screen voltage, resulting in lower than expected plate current. G3SEK  
figured all this out years ago when he designed his screen regulator board. I  
guess I am a slow learner! 
 
The current screen voltage setup shows about 5% more screen voltage with a  
string of dots compared to full carrier. Hence, the question about string of  
dots power reading vs. full carrier power reading. Even the string of dots  
voltage is lower than the design goal so a new G2 power supply is definitely  
warranted.
 
73,
K5GW
 
In a message dated 3/29/2005 10:10:04 A.M. Central Standard Time,  
r at somis.org writes:


On  Mar 28, 2005, at 5:53 PM, Gary Schafer wrote:

> If it is a peak  reading bird it should show the same as with carrier.

... provided that  the anode PS is regulated and one takes a reading 
before the coax  melts.
>
> 73
> Gary K4FMX
>
> TexasRF at aol.com  wrote:
>>
>> And, along a similar vein: If a string of 50%  duty cycle dots at say 
>> 50
>> words per minute are  transmitted, what should the Bird meter show for 
>>  power
>> output compared to full carrier?
>>
>>  73,
>> Gerald K5GW
>>
>> In a message dated  3/28/2005 3:14:31 P.M. Central Standard Time,
>>  Dennis12Amplify at aol.com writes:
>>
>> 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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Rich  Measures, 805.386.3734, AG6K, www.somis.org