First, verify transmitter output using the indirect method.
Next, how close to the TX is the Bird? If it’s a good ways down the feedline, you might not be at a phase low (or somewhere other than a phase peak), which the Bird can’t measure, but which can throw off the accuracy.
Check the Bird element in a different meter at a different, known power site. Is it showing the correct power there? Check a different element at this trouble location, does it also measure low?
Some cross-comparison will help you narrow down if the issue is with the element or with the meter body or line location, etc…
Also, depending on the TPO, a couple thousand watts difference on the meter might just be within its margin of error. Worth doing the math on that too, if you haven’t already.
From: Steve Tuzeneu [mailto:firstname.lastname@example.org]
Sent: Monday, November 06, 2017 10:21 AM
To: CRTech <email@example.com>
Subject: [CRTech] TPO Puzzle
Let’s suppose you just installed a brand new transmitter. You sent your Bird meter to the factory for calibration and it’s back and it’s in the rack.
You power up your new transmitter and set it to your licensed TPO.
You look at your freshly calibrated Bird meter and it says you’re putting out a couple thousand watts less than your licensed TPO.
What’s going on? I can’t give specifics, so don’t ask on the list.
Thanks for your thoughts.
Steve Tuzeneu, CBT
Network Staff Engineer
Bible Broadcasting Network
P.O. Box 7300
Charlotte, NC 28241-7300
704-523-5555 Extension 138
Member: Society of Broadcast Engineers
G.R.O.L./N1XXE-Extra Class Amateur