On Sun, 04 Jan 2009 22:30:27 -0800, Jeff Liebermann
wrote:

On Sun, 04 Jan 2009 10:55:21 -0800, Richard Clark
wrote:

well-heeled Ham "could" achieve the determination of RF power to
within 0.1dB of its actual value.

RF power at 14.1MHz or including all the spurs and harmonics that come
with it? They're probably not much of an issue with the typical ham
100watt xmitter, but certainly are a problem with QRP hardware that
sometimes has no output LPF of any kind.

Hi Jeff,

Power is heat in this particular scenario. All forms of heat
contribution lend to error. The specification (in part):
4. That application is measuring the full power applied from a 100W
rated Ham grade transmitter/transceiver
is sufficient and necessary for the challenge's purposes.

Also, do you want the 50 ohm terminated RF power, or measured through
the line to a random antenna load?
7. That outcome of accuracy of power determination being applied to
the nominal 100W of power at the load and not the nominal 10mW of
power to the sensor.

Consult the complete part 4 specification for alternatives in the
load.

3. That power is 10mW.

0.1dB is about 2.3% accuracy. Plenty of lab grade hardware around,

That is why I selected that power level. An instrument does not
encompass a system, however.

but none with 10mw full scale sensor:
http://www.bird-electronic.com/products/subcategory.aspx?sid=79

None? And this is in the same span of a paragraph regaling the
commonplace accessibility of lab grade hardware? I now have to ask
what kind of lab are you thinking of?

However, with a $1000 prize,

Prize? Was the posting so long as for the purpose of $1000 to become
so aggrandized?

I guess something cheaper will be
required. How about a:
http://www.ohr.com/wattmeter.htm
Not anywhere near as accurate as you want, but for a single 14.1Mhz
frequency, I would have no problem using a properly calibrated signal
generator to create a calibration chart. Also, some environmental
isolation and a temperature compensation chart will be useful.

Accuracy is in the calibration. I have calibrated some pretty rough
looking gear to accuracies that better commercial equipment. The
specification was purposely tailored for Amateur application, to the
least constraint, to the maximum of accuracy, for the cheapest cost.

Ummm..... why do you need such accuracy?

I don't.

Is there some kind of QRP
ultra low power contest that I don't know about?

Possibly. There are a multitude of activities you may be unaware of,
and I would be the last to know.

Amateur metrology?

Yes, a conceptual strain apparently. In this age where the closest a
Ham gets to technology is pushing a credit card across the display
case for a new toy, this has proven to be asking for too much.

Send the $1000 to the address below.

Send it for what? Do I sign as Treasury Secretary Paulson?

73's
Richard Clark, KB7QHC