[Amps] Bird Element Calibration?

[Gary Smith]

Has anyone thought of calling Bird corp and asking this question?  If I were to measure power out with a bird meter, I would accept it as "that's that."  I used to care for my watt meter and the elements with the same care as I would give a piece of fine crystal.  Imo, there was something special in there and I didn't want it to break.  And if an element looked damaged, off it went to Solon, OH for a checkup. And for all of the elements the were returned from the checkup, none were found to be "out of spec." 
 The readings of power out on  bird wattmeter have been as accurate as can be obtained.  And that has been over the entire long haul.  At the risk of sounding simple, volts x current draw = watts,  power in. Look at the bird, that will give watts going out to the world along with the efficiency (inefficiency?) of the transmitter.
I'll wager  a buck or two,  if one lined up a random number of bird elements and took the reading a random moment in time, the difference from all the readings obtained from  all of the elements wouldn't make a tinker's dam.
Bird is generally accepted as "the standard for power output measurement."  That's good enough for me.  Ah...it's plain to see I'm not much of a philosopher.
My .02 on this
73 to all,
Gary... wa6fgi

   
  ----- Original Message ----- 
  From: G3rzp at aol.com 
  To: david.kirkby at onetel.net 
  Cc: amps at contesting.com 
  Sent: Monday, March 21, 2005 1:03 AM
  Subject: Re: [Amps] Bird Element Calibration?


  For real fun, how do you measure the power (with what accuracy?) into a  load 
  such as marine antenna at 2MHz? The dummy load is typically 10 ohms in  
  series with 250pF: a DC calorimetric method might do to calibrate the resistive  
  part, but the RF and DC resistances are probably slightly different. How much  
  loss is there in the capacitor? If you put it on a network analyser, how good 
  is  the answer at this return loss? How accurate is a thermocouple meter? The 
  books  say that you can calibrate a thermocouple with DC, but that ignores skin 
   effects, which tend to make it read slightly high at RF. I believe 
  manufacturers  actually compensated for this by putting a slightly higher figure on the 
  scale  for applications where it mattered - which most of the time, it 
  doesn't.
   
  I have a very hard time with people who insist on quoting numbers to  
  emaningless digits - like 2 decimal places of dBs, when most of the time,  they'll be 
  lucky to have measurements to better than 1 dB anyway. But they wil  do it, 
  because the digital readout gives them great resolution!
   
  73
   
  Peter G3RZP
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