Bird RF Power Analyst 4391A

• Bird RF Power Analyst 4391A
  Posted by Sparks on 23 Jun, 2016 17:24
• Does anyone have experience using the 4391A digital wattmeter? Just got a new one for work and it doesn't give the same readings as my analog meters.
  
• #1 Reply
  Posted by TheSteve on 23 Jun, 2016 18:12
• How different are the readings? Anything that uses the Bird elements is generally not super accurate. CW is +-5%, PEP is +-8% of full scale - that is a pretty big range.
• #2 Reply
  Posted by uncle_bob on 24 Jun, 2016 00:31
• Hi
  
  How far off are the readings and what is your test setup? There are a lot of odd quirks in how some of this gear comes up with the numbers they report. For that matter, when was the last time any of the gear was calibrated and what was it cal'd against? In my case the Bird and it's slugs haven't seen a cal lab in many decades.
  
  Bob
• #3 Reply
  Posted by Sparks on 27 Jun, 2016 19:25
• While feeding in 27.5 Watts using a 250 Watt forward element the unit read 21W max. The manual says the forward power should be atleast 10% of the Forward element. It finaly read corectly shen feeding 33.5W. I tried multiple setups and found that if the antenna does not match the frequency perfectly, the meter reads extremely low, while analog meters read full power forward and reflected.
  
• #4 Reply
  Posted by uncle_bob on 27 Jun, 2016 21:48
• Quote from: Sparks on 27 Jun, 2016 19:25

  While feeding in 27.5 Watts using a 250 Watt forward element the unit read 21W max. The manual says the forward power should be atleast 10% of the Forward element. It finaly read corectly shen feeding 33.5W. I tried multiple setups and found that if the antenna does not match the frequency perfectly, the meter reads extremely low, while analog meters read full power forward and reflected.
  

  
  Hi
  
  I believe that the accuracy spec is a "% full scale" number. A 5% full scale error spec would allow the 27.5 to read as anything from 15 to 40 watts and still be in spec.
  
  Bob