Posted by
Dick Dickinson on
Dec 02, 2018; 10:14pm
URL: http://elecraft.85.s1.nabble.com/K3-SWR-Numerical-Indication-tp7643839p7646748.html
Hi John,
Per your suggestion, I ran a sweep of my 40 meter vertical with the K3 /
K3EZ software.
I then measured at ~20 kHz steps with my MFJ-259B.
Both sets of measurements were taken from the PL-259 that plugs into the rig
or 259B.
Conditions were ~60 degrees F, ground nearly saturated.
Attached is an image of the results.
Kindly,
Dick - KA5KKT
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Hi Dick,
An EZNEC and SimSmith model of the on ground 1/4 wave vertical:
https://www.kn5l.net/images/SS-KA5KKT-vertical.png
SimSmith R1 represents ground loss, the value set to establish a 50 ohm load
at the transmitter, G in SimSmith.
According to the models, the 7 to 7.3 MHz SWR is a little below 1.3.
A flat measurement using the K3 SWR meter seams reasonable. My suggestion is
to use a Antenna Analyzer to measure the antenna and system.
John KN5L
On 12/2/18 12:16 AM, Dick Dickinson wrote:
> I have a full-size monoband vertical for 40 meters. Simple
> architectural aluminum tapering from 1 ¼ (?) in 6 telescoping
> sections. The radial field is designed to provide a 50 ohm match at
> the feed point
12 13+ radials. It is fed directly
no matching
> device with RG-213 from the remote antenna switch about 50 away at my
> tower. The coax from the rig to the remote antenna switch is
> estimated to be ~ 50 in length. A lot of the time running K3EZ to
> sweep the band (typically 20 watts), it will indicate a
> 1.0:1 SWR from 7.0 MHz to 7.3 MHz in 20 kHz steps. Occasional
> deviation from one K3EZ run to another might be due to variations in
> moisture content of the ground or less than perfect connection to the
> vertical
an uncommon situation. The K3 shows the same readings.
>
> Is this 1.0:1 SWR across the entire 40 meter band curious or remarkable?
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