On 30 Mar 2005 19:16:44 -0800, "Brian Kelly" wrote:

Since coax losses don't vary much if at all over any of the individual
HF ham bands a decent inline wattmeter with maybe a 4 inch scale should
allow me to maintain a constant power output over the sweep.

Hi Brian,

I left that unsaid, expecting someone, if not you, would also come to
that conclusion. It does not work across all bands, but within a band
it will suffice. Also, even given the impression of accuracy that
most impart to their power meters, this method demands only "relative
accuracy" which can be exceptional when care is shown (try to maintain
a full scale indication or at least greater than 2/3rds at some
cardinal point on the scale).

At this point, one should reflect that if there is a mismatch, then
power at the feed point will vary somewhat. In other words, the
presumption of constant power (to subtract out the effects of the
transmission line) is violated. However, as a first pass estimation,
the method is still quite productive, and tightening up the method and
the numbers is an exercise left to the experimenter.

73's
Richard Clark, KB7QHC