[Amps] transformers

[Peter Chadwick]

>I've just never seen that power on 
accurate  meters.<

Accurate RF power measurement isn't quite as easy as it may sometimes appear. So much so that for European Standards, a measurement uncertainty of +/-0.75dB is allowed. That does include such things as mismatch errors, too. 
One old wive's tale is that you can use a known load and measure current with a thermo ammeter. Because the ammeter works on heating effect, you can calibrate it at DC. Unfortuantely, the effects of skin resistance don't help here, tending to make the ammeter read higher as the frequency goes up. Probably the most accurate method is calorimetric, using constant liquid flow (a constant head apparatus) and then substituitng DC to get the same temperature differential across the inlet and outlet. This cannot be considered a rapid measurement.........and it does require a tx capable of continuous duty.
Real fun is trying to measure accurately the power in a non 50 ohm (or non 75 ohm some years back) system.
Even the use of a directional coupler has its problems - directivity, mismatch losses at connectors, etc. They all add to the measurement uncertainty.
vy 73
Peter G3RZP