28 Foot Experimental Vertical
|
|
||
|
|
28 Foot Experimental Vertical |
|
|
|
||
This was constructed to prototype and better understand vertical antennas.
The purpose for displaying here is to show others how simple the experimenting
can be and to (hopefully ) get a little constructive feedback for further experiments.
The top mast is from a salvaged CB antenna and is about 18 feet long.
The lower mast is a piece of generic TV antenna mast.
The pivot on the bottom comes from Radio Shack.
The plastic crate that the mast is setting on is a Coke soft drink case serving as a
ground insulator. It is spiked to the ground with four gutter spikes.
The mast is bracketed to the shed without insulation. I choose to ignore losses and I
don't feel my 100 Watts will create any problems.
The subject antenna is in the foreground.
The tower in the background is a crank up from the late 1970's.
Same view, just back a bit.
This shows the bracket and the connection between the upper & lower mast. The jumper
wire is the point where an inductor my be inserted. I use Stainless hose clamps to make the
electrical connections.
Same subject, different angle.
This is the plastic box insulator that keeps the mast from being grounded.
I keep looking for a suitable wine bottle to replace it!
I found this plastic box at the home improvement store that is intended as an enclosure for a lawn sprinkler valve.
It works great as an insulator and support for the bottom of the antenna. I think it was about $13.
Same subject, different angle.
Here is the base loading coil I used to match it on 40 and 80 meters. What you see is
the 80M tap. The 40M tap is only a couple of turns and the 160M tap is about 3/4 of the
length. The loading coil alone does not provide a good match but is usable on 40, iffy
on 80 and unusable on 160. I got a little better results using a Dentron Jr. match box.
The antenna complied with the EZNEC model.
I believe that a good match would be accomplished by applying the TLW program
that is supplied with the ARRL Antenna Handbook. I have not pursued this yet
because I am reluctant to buy suitable capacitors until I am certain I cannot make
them.
What appears to be an AC line connector is my radial connector. I use AC extension
cords plugged into this connector as radials. Primitive, but expedient. I have a
number of long cords that are easily deployed and recovered. Remember, this is a
learning tool, not a permanent antenna!
Same subject, different angle.
More to come later as I progress!