80/75 Meter 4-Square Array

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This array has been in use since 1989.

The SWR from 3.5 to 3.9 is below 1.5:1

The F/R of the array is 20dB average and with some signals even better.

View of the 4-Square from the top of one of my towers.  (Approx 125 feet high)

The radial system consists of 90 1/4 wave long wires attached to the base of each vertical.

Close-up picture of the support post and base of the vertical.

Each vertical is mounted on a 6 inch square by 12 foot long pressure treated post.

The posts were buried 4 feet in the ground.

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• The verticals are 65' tall.  40 feet of 4" and 25 feet of 3"  aluminum irrigation tubing.  The joint overlap is 1'.
• I have replaced the UV resistant bale twine (guy ropes) with 3/16" (770lb. tensile strength) UV resistant Dacron rope.  
  

You can also find this image on page 9-57 of ON4UN's - Low Band DXing Book, 3rd edition.

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• Each support post is 6" x 6" x 12' pressure treated.  4' of the post is in the ground..
• The vertical is insulated from the post by PVC electrical conduit.
• The support arms are made from 1/2" thick Plexiglass (Acrylic) sheet.

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• I used a 1 foot overlap at the joint between the 4" and 3" tubing.
• 3-1/2" Sch. 40 Aluminum conduit (pipe) has to be machined to fit inside the 4" irrigation tubing.
• 3" Sch. 40 aluminum conduit (pipe) is used to transition from the 3-1/2" conduit to the 3" irrigation tubing.  No machining required on this sleeve.

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THUNDERSTORM!!

Check out these pictures of a thunderstorm that was a bit too close for comfort.  Fortunately the cell didn't move directly over the array.  It sure came close though.