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| Beam made by SP3RNZ |
Earlier this year I made a
list of projects and ideas I want to do/make. One of them is to build a 70MHz yagi. I was thinking about a LFA fro 70MHz (4m band) since I already have a 6m yagi. Then I look at my antennatower and thought....I need more coax (extra cost)....the extra antenna gives extra weight (dangerous). But I really want a antenna for both 6m and 4m....
During the PE75FREE activation I learned about a 4m/6m combi antenna which was installed by
PE5TT Marcel (who was PG75FREE). He bought his antenna called a EA5070-OWA9 which is a 4 elements for 6m and a 5 elements for 4m on one boom. Only the 6m dipole is fed and the 4m antenna is fed by inductive coupling. Now searching the internet I came across a
similair design by YU7EF, only this one is 5 elements for 6m and 5 elements for 4m. Boom length is about 4,2m. Interesting since I have a boom from a donor 11m beam which is 4m long and can be extended very easily. Actually Marcel has good results with his beam and I found the design and construction simple enough to try and build this beam myself. This way I can keep the costs low. Working for a hardware shop has benefits and I can easily get all materials without additional transport costs which are unbelievable high when ordering large aluminium pipes.
So, I started constructing...
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| Boom from a Sirio SY4 11m beam |
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| Piece of metal I prepared to help as guide drilling the holes to mount the clamps holding the radials |
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| These are blind rivet nuts, handy if you don't want to drill through the boom entirely and use large bolts. It's a choice, got the idea from the construction seen at my borrowed 10m LFA beam. |
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| First try drilling holes for the rivets went wrong. I thought I would not have a problem mounting it over the original hole that was in there for the original reflector. Faults can be made I should have taken another place, so I choose to drill through the boom and use long bolts for this one. I'm not perfect and this is what you get when using old parts... |
Update of progress wil be made soon in a next post.
