Thursday, June 11, 2020

4m/6m yagi - new antenna project

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...

Boom from a Sirio SY4 11m beam
Piece of metal I prepared to help as guide drilling the holes to mount the clamps holding the radials
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.

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.

4 comments:

  1. Leuk project Bas. Ben benieuwd naar het resultaat.

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    1. Ja ik ook. Marcel heeft goede resultaten met zijn antenne. Ben benieuwd of het ook werken gaat zoals het moet. 73, Bas

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  2. Hallo Bas, doe je goed. Dat gaat weer mooie dx opleveren. 73 Paul

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    1. Dat hoop ik Paul, het moet eerst nog even gaan werken. Boom van 4,20m, sommige amateurs zijn al blij als ze een buis van 4,20m aan de muur kunnen hangen om een antenne op te maken. Ben wel heel blij dat ik in principe ruimte heb om dit soort projecten te kunnen realiseren. 73, Bas

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Thanks for your comment. Bedankt voor je reactie. 73, Bas