In recent correspondence we have been regaled with the possibilities,
the probabilities, the certainties that some fastidious, and
well-heeled Ham "could" achieve the determination of RF power to
within 0.1dB of its actual value.

This gives me considerable pause as to how that actual value was
determined itself, but the explanation of that drifted into the fog of
vague generalization and the dismiss of standards. I characterized
this as delusional at worst, and simply fantasy short of being
fantastically rich.

So, given the swings of claims that seem to hinge on access to exotic
equipment, I was offered:

On Sat, 3 Jan 2009 , wrote:
A ham seriously interested in 0.1 dB measurements will probably be
able to scrounge up something to use as a transfer standard
....
The how to do it is all out there. What was "state of the art" for a
national laboratory in 1970 is fairly straightforward garage work
these days, and, a heck of a lot easier because you've got inexpensive
automation for making the measurements and inexpensive computer power
for doing the calibration calculations and uncertainty analysis.

None of these suggestions attended any actual real application beyond
the thread's discussion of measuring power from an antenna in a high
power RF field from a nearby (10s of wavelengths distant, perhaps)
transmitter.

The quote above fairly encompass the solution in Jim's own words.
There were certainly more words, and they can be appended to this
thread or those above amended as Jim sees fit to force the outcome to
match the claim. However, I would like to see something a little more
real than fanciful.

This would include a real METHOD and BUDGET for the claim:
On Tue, 23 Dec 2008 10:29:05 -0800, Jim Lux
wrote:
At HF and VHF, you should be able to do power measurements to a tenth of
a dB, with moderate care.

1. That budget (with an ironic eye towards the language's claim of
"moderate") is a generous $1000 - with that budget being invested
solely towards the measurement (and not in the capital equipment of
transmitter and antenna) through the costs of ancillary equipment
acquisition and of guarantees of absolute accuracy as further
described below.

2. That frequency is 14.1MHz.

3. That power is 10mW.

4. That application is measuring the full power applied from a 100W
rated Ham grade transmitter/transceiver directly (or through a
directional coupler) to
a. an unloaded quarterwave thin antenna sited over 120 half-wave
radials placed slightly above, upon, or slightly below the ground
(slightly being defined as that recommended by an NEC modeling tool
for ground radial modeling); or
b. an unloaded halfwave thin antenna sited in free space.

5. That fully expressed tolerances for all components, capital and
ancillary equipment involved where the budget also absorbs their cost
of determination of their contribution to error.

6. That fully expressed tolerances for sources of system error.

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.

* * * * * * * *

This will be a very short thread devoid of conclusion when the
poster(s) suddenly become aware of the expense exceeding the budget.
For those who challenge this artificial budgetary limitation, try
asking Congress for a bailout.

73's
Richard Clark, KB7QHC