Apologies to Max, however...
Max's second post came up when I posted my blurb on getting a graphing
analyzer. Sorry, Max.
However... In the years of correspondence about 160 meter L's over an FCP,
confusion from running blind with an SWR meter is involved in over 3/4 of
those threads. Since the feed R+jX can vary so very much with the
horizontal height above ground, the condition of ground, and other issue,
such things as knowing that a person is getting a feed R of 17 ohms with a
particular vertical wire length and horizontal wire length are really
invaluable in deciding how to move forward.
I would suggest that if people are in possession of R + jX figures for a
problem they are posting, that they should lead with the collection of R+jX
involved. It will surely change the nature of forthcoming posts :>)
For the rest of you, I firmly stand on my post, as amended below, as I have
been buried in the outcomes of SWR only driven confusion for some years
now.
73, and may the fine art of antenna twiddling outlive us all.
Guy, K2AV
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Hi, Max, and anyone else out there trying to make antennas with an SWR
meter....
Oops...
Let's try: To all you out there suffering trying to make antennas with just
an SWR meter...
Not knowing the separate resistance and reactive components and the sign of
the reactance surely does make it hard to figure out what to do next. SWR
will tell you if you got to 50 + j0 or not but trying to get both those
numbers spot on when all you know is glurg plus or minus glub for R and
X is like trying to to find your white shirt in the closet with no lamp and
the door shut tight.
If you really want to fiddle yourself with wire and stuff to come up with
antennas that work in your own situation (that really is a lot of fun) get
yourself a graphing analyzer like an AIM4170 or AEA or RigExpert. (The
graphing devices will allow you to infer sign of X from the slope of the X
curve.) It's kind of like having a flashlight to take into the closet with
you -- much easier to find the white shirt in the dark. Otherwise prepare
yourself emotionally for a lot of groping.
Trying to adjust any antenna more complicated than a dipole with an SWR
meter is like trying to fix your watch with a hammer. An SWR meter is
never worth more than about a tenth of what you paid for it.
Get a graphing analyzer and after a while you will wonder what the h*ll you
thought you were doing before you got it.
73, Guy K2AV
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