I would add only one thing to this. The thing used to measure the SWR can
also be responsible for strange results when the SWR is not low. Don't
always assume that the thing used to measure something is exact all the
time.
Steve
K:9:C:I

"Dave Shrader" wrote in message
news:biGJb.213249$8y1.750188@attbi_s52...
Keven Matthews wrote:

I recently moved my shack from an upstairs room to downstairs, much
closer
to the garden and antennas.

SNIPPED

Kevin, there have been numerous responses to your original post. Let me
be an Elmer for a short moment.

An example of antenna resonance and VSWR follows.

In my mobile I have a resonant 40 meter Hamstick. Resonance means there
is NO Reactance in the antenna impedance. My antenna analyzer indicates
approximately 12 + j0 ohms at 7.225 MHz. This is almost a 5:1 VSWR and
that's what a meter indicates. Now, I added an ICOM AH-4 automatic
antenna tuner at the antenna. The antenna is still 12 + j0 ohms but the
tuner transforms the impedance to 50 + j0 ohms. So, the VSWR from the
antenna/tuner to the 706, approximately 16 feet of coax, is now
approximately 1:1.

Since the length of coax in your installation changes the measured VSWR,
the coax is part of the antenna system and is radiating. So, you need to
isolate the coax from the antenna. There are several ways to accomplish
this. The most direct way is to make a coil of coax about 4 to 6 inches
diameter and having 8 to 10 turns and install it directly at the base of
the antenna. If you have a ground radial system make sure the coax is
underneath [lower] than the radial system. Finally, install some clamp
on ferrites, available from Radio Shack for less than $10, at the 1/4
and 1/2 wavelength on the coax from the antenna feedpoint.

Hopefully this will clean up the RF on the coax.

With a vertical antenna a reasonable VSWR at antenna resonance should be
somewhere between 1.5:1 and 2.0:1.

Deacon Dave, W1MCE