Hi,
I am contemplating a pep reading wattmeter so I can check the output of my HB
amplifier. Consequently, I am putting it right on the output of the amp. The
output of the amp should always see 50 ohms because it will be feeding either a
50 ohm dummy load, or an ATU tuned to 50 ohms. With that in mind, I am simply
using a resistive voltage divider, to get a voltage sample, and squaring it
with an AD633 multiplier. This seems like a simple, cheap way to get watt
info. assuming you will always be working into a near 50 ohm resistive load.
Anyone see any reason why this will not give you a pretty good indication of
your power output? I realize that the load may not always be exactly 50 ohms,
and that there are losses in the ATU.
The reason I have not tried getting a current sample and using the
conventional VI COS Theta with the multiplier is due to the additional
complexity of circuitry. It is also difficult to get accurate current samples
over a wide frequency range. By making everything resistive it somewhat takes
the frequency dependency out of the problem. Thanks.
73 Gary N4AST