Topband: Beverage Construction

[ABowenN4OO]

Installing a Beverage is not a trivial undertaking. I have 4 of my own and
have helped others with theirs. The following procedure has evolved.

I use a "sighting" type compass (Suunto. Look up on internet) to establish
the direction. I then lay out the line using 500-600 ft of small diameter
white, nylon line. Unless you do this, maintaining a straight line through
woods and underbrush will be difficult. An axe and loppers have been most
helpful with clearing a path, particularly in our north Florida "jungle".

For a height gauge, I make up a 9 ft length of aluminum tubing, which helps
to establish a consistent height above ground.

I use only the ceramic insulators that are sold for electric fences. The
plastic ones, being a soft material, tend to pop off as the tree grows. I
anchor the insulators with long, drywall type screws. I have found screws
to be more reliable than the nails. Be sure to use the plastic washers that
come with the insulators. Depending on your rain fall and climate, the tree
will probably grow arond the insulator in about 4 years.

For anchor points that fall between trees that are on line, I stretch a
piece of nylon line between 2 trees to support the wire. The maximum
distance between supports generally should be 40 ft or less. I try to keep
the deviation from the sighting line to less than a couple of degrees.

Alternatively, you could install a post of your own making. In this area,
landscape timbers (8 ft, $2.50), with a 4 ft extension of pressure treated
1 X 4" board works well. So does a steel fence post with a 10 ft length of
1 1/2" PVC pipe over the top. The timbers are cheaper.

I use #17 galvanized steel fence wire for the main conductor. This stuff
runs about 3 ohms per 100 ft and is perfectly satisfactory. I have also
used #18 copper clad steel and #18 insulated wire. I have never been able
to tell that one is better than the other. Steel is a lot tougher. Fence
wire and insulators are sold here at most rural hardware stores and lumber
yards. The other wires were usually purchased at flea markets or scrounged
from a number of sources. 

The start point anchor for my Beverages is a power pole "stub" (cutoff). I
obtained it from the local power company, by signing a form at their
office. If you cannot obtain one of these, which are generally 8-12 ft
long, use 2 landscape timbers, bolted together. I use a guy wire type
insulator and a large turnbuckle which is used to tighten the wire when you
are finished. Go easy with tension if you are not using the steel wire.

For tie wires at the insulators, I use 6" length of #18, single strand,
insulated wire. Be aware that smaller diameter trees move a lot in the
wind. Be prepared to do maintenance after every wind storm. These generally
occur just before a contest. Fallen branches are also a problem and
generally occur during a contest or when a rare one is active.

At the far end, I mount a 500 or 470 ohm, 2 watt resistor in a plastic pill
bottle. This goes in series with the wire, to ground. I have one Beverage
which uses the "slanted to ground" ending and the others simply bend at the
last insulator and go straidght down to ground. I have never been able to
tell that there is any degradation with the wire going vertically for 9 ft
or so.

For a ground rod, I use 1/2 of a 10 ft length of 1/2", M, rigid copper
tubing. These have been on sale at the large hardware stores for less than
$4/length.

The ground at the start/central point should be 2 or more of these same
rods, or maybe multiple 10 footers. I think that 2 short ones are generally
better. I use 2 short ones and about 12 square feet of 1/2" hardware cloth,
which happened to be on hand.

I make my own 10/1 transformers using .500" OD cores of #43 material. This
core will hold about 10 turns of #24 insulated wire taken from multi
conductor telephone wire cable. Wind a 3 turn primary between the ends of
the larger winding. Put a 470 ohm resistor across the large winding and
measure the impedance on the small winding with your MFJ or Autek Analyst.
You should measure around 50 ohms. If not correct, adjust the turns on the
large winding. 

You can also construct the transformers as shown in ON4UN's book, Low Band
DXing. I have made them both ways and my ear cannot detect any significant
difference. The instruments I have show that the impedance ratio is
maintained over a wider frequency range with the trifilar winding. I do not
have equipment for measuring the efficiency. 

You can mount the transformer and connector in a plastic utility box. I use
the small blue ones that are handled by the large hardware/lumber places.
Use 2 machine screws for antenna and ground. Hook the small winding to the
coax connector. All my coax cables run to a 4 position relay box, remotely
switched from the shack. I use a separate transformer for each antenna.

For lead in cable, I use RG6. This has been available at local ham flea
markets for very reasonable prices, such as .04 per foot. Losses are very
low with this cable and at these frequencies. I am not concerned with the
small mismatch between the cable and the output Z of the transformer.
Anything under 3:1 is OK with me at these frequencies.

Summer is not a great time to construct Beverage antennas in the southern
latitudes.

For installation in the woods, I use a 6 ft aluminum step ladder, the
height reference and a pail containing the insulators, screws, battery
drill motor, tie wires and other tools. Don't forget the extra nylon line.

It is not exactly an "all you gotta do is..." project.

Incidently, my Beverages are also very effective on 80/40/30M. 


INK N4OO






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