Lionel GW-180 Throttle Markings

I get an analog voltmeter and mark the voltage on the transformer.

According to the GW180 manual the throttle is marked in % of Power output.  At a given throttle position the Output Voltage will go up or down depending on the combined electrical Load (number of motors, cars being pulled, curves, lights, etc.).

Since the GW180/PH180 combo puts out variable 0-18VAC, a throttle setting of around 75 - 90% should be about 14-16 volts, depending on the load.

Thank you Rod and Steve

Note that any cheap voltmeter will not give accurate readings with a chopped waveform, you need a true-RMS meter to measure non-linear waveforms.