Element to Boom Interface 80 Meter Beam Ve6fi
Since the element is approximately 90 ft long it must be supported to the
boom by the 1/8 inch plates shown below. They are 28 inches long so that
the interface is spread over a larger area. The square plate (not shown) which
is on the end of the boom will attach to these brackets.
Extension of the Element
The triangular portion of the element is 64 feet long. The brackets shown
below in the next two pictures will support the rest of the element which
consists of 120 inches of 1.25 inch Al pipe, and
another 96 inches of fiberglass tubing that houses fixed copper tape.
Boom Assembly 2 element 80 meter bean Ve6fi
Below is the boom section of the 80m beam. It is 32 feet long. The pipe on the left is a torque tube and it will be placed in the center of the boom. The triangular tower section does not have to much resistance to twist. As such the torque tube which will be bolted on each end and in the center will resist the torque created by uneven wind forces or uneven ice loads on the 100 ft. elements. The torque tube is built out of 3 inch AL pipe Schedule 40.
Shown below is the center of the 32 foot boom. Shown is the cradle and the center support for the torque tube.
Below is the 80m beam without end pieces attached. It is installed at a temporary location until I finish the rest of it
and build the 150 foot tower to put it on.
The mast is 4.5 inches OD Schedule 40 steel pipe. The cradle that holds the Yagi is shown welded
to the mast. The cradle is made out of 1/4 inch steel and is 36 inches long.
As shown below both elements will be isolated from the boom and will both will have coils at the center where the inductance is varied by compressing or elongated the coil turns.
Below are Denis ve6aq and Ted Ve6kib working on the software to control the stepper motors on the 80 meter Yagi. The software will enable both elements of the array to be tuned so that the antenna can operate from 3.5 MHz to 4.0 MHz.
Below is a screen shot of the graphics used to control the antenna parameters. For example if you wanted to operate at 3.750 one would tap the 3.750 button. Since the antenna is in 'forward fire' it would adjust the elements into a Driven element/ Reflector combination.
The graphic software talks to the Controller at the base of the tower. The Controller is run by a PIC which controls the two stepper motors on the antenna. One stepper motors is utilized for tuning the coil on the driven element and one motor is used for the reflector/director.
If one wishes to change antenna direction by 180 degrees without rotating the antenna one would click on the 'backward fire' and the antenna would be adjusted into the Driven element - director configuration.
On initial setup the coil setting at each frequency can be changed and saved into the program. I will probably do that while monitoring the front to back ratio.
