The adjustments are in the manual. Road squawker posted a link and gave you a page number. Twist them until the meter readings make you happy. You do need a dummy load to calibrate it properly.
You can get two meters to agree at one point but they will never give you the same reading across the scale. Doesn't matter if its a bird, palstar, mfj or dosy.
This is true but if I buy 10 Bird 43s and 10 of the same slugs, and set them up with my bird DL and one of my radios and set it at say 100W, I can guarantee you that most of those 43s are going to be pretty close to one another. The reason people chase Bird and CD meters is the REPEATABILITY of the measurements is a huge asset. There is rarely such thing as a bird meter that's "way out of adjustment. " They generally either work correctly or they're totally broken (because it fell off a tower and the lens hit a branch on the way down, lmao) This repeatability is a very good reason they are more or less considered the gold standard.
If companies like Palstar can't be bothered to make a meter that isn't crap they should
just sell the product without it. Frankly a 4K tuner should have an option of just buying it with a bird directional coupler built into the thing. Anyone with that much of an equipment commitment isn't going to want to play with junk anyways. A poorly set up or QCed meter is a waste of time for the buyer.
-Mike