Bird Wattmeter Calibration. The trimmer is located underneath the frequency range power label which is glued to the top of the element. Diode Fixes Remove them.
The 43 Wattmeter is a field-proven portable insertion-type instrument designed to measure both forward and reflected CW power in coaxial transmission lines under any load condition. The trimmer is located underneath the frequency range power label which is glued to the top of the element. Quick fix for this problem that works sometimes.
Read both forward and reflected power.
Actually the Bird type 43 wattmeter elements slugs do have a calibration adjustment but it is done at the factory. Fixed 25-1000 MHz 5-500 Watt Element Wattmeter. Plug those monsters in through the top of the meter housing and rotate the whole slug for forward or reverse. Read both forward and reflected power.