Larry's Antennas LLC
KJ7U Antennas Striving for and Achieving Perfection
KJ7U Antennas Striving for and Achieving Perfection
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Base Station Install for mobile models. Tunable Vertical Base model has different instructions and comes with aluminum radials.
It is wise to use a grounded coax switch at the transmitter site, which will ground the coax when not being used.
A lightning arrestor is also recommended for base installations.
This rough drawing is only that. Actual number of wires or lengths are not critical.
Longer is better, and also more wires it better. 8 wires 14' with at least one longer will work when
antenna is on a roof or elevated more than 10 feet above the ground. Run one longer wire to a ground rod.
It is wise to use a grounded coax switch at the transmitter site, which will ground the coax when not being used.
A lightning arrestor is also recommended for base installations.
This rough drawing is only that. Actual number of wires or lengths are not critical.
Longer is better, and also more wires it better. 8 wires 14' with at least one longer will work when
antenna is on a roof or elevated more than 10 feet above the ground. Run one longer wire to a ground rod.
When mounting on a roof, why not run wires to the other edge of the roof.
When elevated radials are nearer to the earth, say elevated less than 10 feet,
then in many cases as few as 6 radials 63" will couple to the earth and allow the antenna
to tune all the bands 6-160.
The actual antenna is only half of the system, the image plane or radials are the other half.
The center conductor goes to the antenna and the shield of the coax connects directly to
the radial wires through a common ground bolt or buss. The fewer connections, the less chance of bad connections. In other words,
make the wires one piece each or if splicing, solder connections. All connections will corrode
in time, so use conductive never seize compound on them and also seal with battery protector.
The thumb screw on the antenna connection will only need Never Seize or anti seize compound.
Longer whips can be used for more efficiency on Low bands, but will not then allow
operation on higher bands like 10 meters. I have a 90" whip on my chimney mounted antenna
and works great on all lower bands, but not 10m. To work all bands 6-160, use 63" up to 72" whip.
The distance from common ground bolt to antenna should be about 3 or 4 inches.
Keep radials up near antenna. The image plane or radials must be up near the antenna.
In other words you cannot elevate the antenna 20 feet and put the radials on the ground. At this time we only have 63" whips available. They work fine on all the bands.
When elevated radials are nearer to the earth, say elevated less than 10 feet,
then in many cases as few as 6 radials 63" will couple to the earth and allow the antenna
to tune all the bands 6-160.
The actual antenna is only half of the system, the image plane or radials are the other half.
The center conductor goes to the antenna and the shield of the coax connects directly to
the radial wires through a common ground bolt or buss. The fewer connections, the less chance of bad connections. In other words,
make the wires one piece each or if splicing, solder connections. All connections will corrode
in time, so use conductive never seize compound on them and also seal with battery protector.
The thumb screw on the antenna connection will only need Never Seize or anti seize compound.
Longer whips can be used for more efficiency on Low bands, but will not then allow
operation on higher bands like 10 meters. I have a 90" whip on my chimney mounted antenna
and works great on all lower bands, but not 10m. To work all bands 6-160, use 63" up to 72" whip.
The distance from common ground bolt to antenna should be about 3 or 4 inches.
Keep radials up near antenna. The image plane or radials must be up near the antenna.
In other words you cannot elevate the antenna 20 feet and put the radials on the ground. At this time we only have 63" whips available. They work fine on all the bands.
Check the Arrl handbook for safety issues with antennas.
Here is a drawing showing a basic installation. Note: These antennas can be installed on larger size water pipe by drilling a hole in a pipe cap for mounting the included mounting post.
