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First was to decide what type of materials and housing to use. I chose to use PVC water pipe. I selected 4" for one and
2" for the other to enable me enough room on the inside to construct the coil needed.
After some internet research on BalUns I learned a coil was needed to form a transformer of such. I used Belden 9913
coaxial cable to construct the 4" BalUn coil and RG-58 to construct the smaller 2" BalUn. The length I used was 19' feet.
A tight wound single layer coil was constructed on the inter diameter of both the 4" and 2" PVC pipe.
Careful separation of the braid was taken to properly form the mirrored leg connection. Take your time, it's worth it
to not have stray braids. KI6KNA had the patients to do this step.
Here the braids were arranged and held in place with a light coat of solder. Then lugs were installed to attach them
from the inside to the dipole leg posts.
SPECIAL NOTE: The above photo shows the critical position of the dipole leg connections. I found I was not able to achevie
an acceptable SWR untill I positioned the dipole leg connections up and out of the magnetic field of the coil. I used an arched
form.
Now that the coil was in place, connections need to made. On the bottom of the the coil I installed a chassis mount N-Type
connector which will late be mounted in the center of the bottom cap. The connections for the dipole were constructed
using copper 1/4" 20 thread bolts, washers and nuts. The bolts were inserted in a strip of copper sheeting to form a copper
tab then the heads of the bolts were soldered to the strips and inserted through the PVC pipe near the top of the coil. Be
sure to leave room for the top cap! Secureing the bolts on the outside with a washer and another copper nut for locking.
The same care should be taken here for preparing the braid.
Next is to installed the top cap. In the center of the cap I drilled and installed a 1/4 " eye bolt. This enabled me
to use a D-Ring, rope and pulley system to lower and make adjustments, then rasie it for operations.
Install the bottom cap with a center installed N-Type chassis mount connector. Use a little RTV on the inside for weather
proofing.
Below is the finished unit, modeled by KI6KNA. The whole project was completed in an afternoon. Nasa sticker was added
to electrically gather more signal from the air. hehe.....
Now I simply cut to length 4 dipole legs, 80m, 40m, 20m and 10m, securing them with copper lugs and solder, hoisted
them up the tower. With a little help from Bob KD6DYR and his MFJ antenna analyzer we manuvered the legs into usable
VSWR positions.
A little hard to see by this shot, but there she is in all her glory! Multiband inverted-Vee. The whole project cost
was under $30.00 and will probably be around for the next 100 years.
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