On Sep 5, 11:00*am, "Dave Plowman (News)"
wrote:

Ah - right. Those can be fine, accuracy wise. But of very limited use.
After all it's not difficult to work out what most appliances cost to run..

Don't think small! I've used power meters to do LOTS of tuning
operations.
Consider an AB power stage, where 50W peak is available; you might
allow 2W of quiescent power dissipation, and that means (under no-load
conditions) cranking the final stage bias fully down, powering up the
unit,
and watching the power meter while slowly tweaking up the
bias pot. When it gets to x + 2W, you're done.

RF output power is awkward to measure, too; tuning a power
oscillator with a power meter on the AC input is ... luxurious.
Look, ma! No more RF burns!

And that little kill-a-watt is a much nicer way to find out what the
(duty-cycle-according-to-humidistat) dehumidifier really costs to
run down in the basement, than an A/B comparison on 2006 and 2007
electric utility bills. I did the electric bill comparison first.
Wish
it was the other way around.