KW-1P Power Meter !
The "real" story: During a fitful night of sleep after too much food and wine, the "vision" of this wattmeter came to me in a dream. Upon waking I immediately knew what I needed to build. In my dream I was in the Collins plant (looking at the cars in the parking lot I would guess the year was around 1955 or so ...) and saw this wattmeter being prototyped in one of the labs. "Wow," I thought, "the perfect wattmeter for my KW-1." The result of what I saw in the dream is below.
I have heard stories that Collins actually DID prototype such a wattmeter. One, from a somewhat questionable source can be read here.