[Amps] Question on Ameritron amp wattmeter circuit

[n1rj at pivot.net (Roger D. Johnson)]

 To properly sense power you must sample both the current
and voltage on the line. The toroid acts as a current trans-
former to sample the current and the caps act as a voltage
divider to sample the voltage. I don't have the schematic
for reference, but I suspect the variable cap is used to set
the power reading. 

73, Roger