LOW BAND ANTENNAS
The picture below shows one of the receiving antennas at AB0X.
It is a long "U" or a short "B". In other words it is a large
EWE antenna or a very short beverage antenna. Lance Johnson's Elbert County
Preamp ECP-1 is used to match the antenna to the coax and provide some
pre amplification of the low noise sigs heard on 160.
Here's a close up at the feed point of the antenna. It is
difficult to see but a ground rod is located in between the wooden stake
and the 8' PVC pipe used to support the 100' of horizontal wire. The ECP-1
has a 9:1 transformer and a pre amp inside the plastic enclosure. It is
pointed in a Northern direction. The far end of the antenna is terminated
thru a variable resistor set at 1000 Ohms to ground.
Shown below is the shielded loop used at AB0X for low band low
noise receiving on 160.
The loop is rotated by simply moving the loop to another set
of nails in the deck at a
different angle. It is effective in nulling out noise in the
area. The loop is resonated for 160, but a switch in the plastic
box is used to withdraw a fixed parallel capacitor which
brings up the resonant frequency to 80 Meters. As a result the loop
can be used on 160 and 80. However, a trip outside is required to change
The photo below shows the feed point of my folded EWE antenna
(ala K9AY) that is located at the back edge of the lot. My 10 MHz. vertical
is used as a support for the antenna. A piece of PVC has been attached
at the top of the vertical to insulate the wire from the vertical section.
The antenna is fed through a 9:1 transformer. The vertical allows
a symmetrical triangular shape. The antenna is still under test but shows
some signs of being an asset to a low band QTH which is too small for a
full size beverage antenna.
The photo below shows the gamma matching device used to shunt
feed the tower on 160 on the right of the tower. This serves as the transmitting
antenna on the Top Band. The gamma matching unit is enclosed in a K-Mart
plastic box and keeps the elements out of the unit. Number 8 aluminum wire
runs up approximately 40' up the tower and is spaced at 3' feet on
the side. The antenna has proven itself to work well, with
181 countries confirmed on 160. The 80 Meter gamma matching unit is shown
on the left side of the tower. It is spaced a little wider than the 160
unit but only runs up about 32' on the tower. It is tuned for 3505, but
a relay in the unit is switched in to change the fixed capacitors in the
matching unit to make it resonant at 3790. Over 250 countries have been
worked on 80 with this antenna and a 1/4 wave sloper on the tower. The
tower has 16 full sized 80 meter radials attached at the base and the ground
system is wired to the phased 40 Meter verticals radial system which has
85 full size 1/4 wave radials buried under it. Over 100 radials are attached
to the ground screen that is buried under the entire backyard.
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