1. Clean brass pipes. 

Clean both brass tubes of any dirt like corrosion or label adhesive.  Some paint thinner or varsol may help for this procedure.  You may also use some fine sand paper or emery cloth for those hard to remove dirt.  

2. Mark the drill points on the boom. (See ANTDL6WU report for detailed information)

Use the following suggested procedure for marking the drill points.

A.  Lineup the tip of the 7/32" x 1' Brass Square Tube at 278.11mm on a straight edge ruler (276.11mm for the director 8 element plus 2mm to space it from the tip of the square tube).

B.  Mark the following values on the Square Tube. 

This should leave approximately 26.69mm after the reflector element.  This should be enough space for a bracket or harness to mount the yagi.

3.  Drill the mark points on the boom. 

Use a 7/32 drill bit on a drill press and drill through all the mark points on the square tube.  Drill all the way through the square tube creating two holes (one on each side of the pipe). 

NOTE:  I would strongly suggest not to free hand the drill points using a hand drill unless you have a good sturdy hands.  The idea is to make the holes precisely right to have the elements tightly fit on the hole.  This will make it a lot easier to center the elements during assembly.

4.  Mark and cut the elements. (See ANTDL6WU report for detailed information)

Using the 3/32" x 3' Brass Round Tube and a ruler.  Mark and cut the brass pipe using the following values. 

Measure and cut one element at a time.  Start from the longest element (reflector) to the smallest (director 8).  This ensures that in the event that the element is undercut, the element can still be use for the next element size down.

Use a file or the top side of  the rotary tools cutting disc to fine cut the elements to the right size.  You can also use a caliper to measure the elements to the precise size or just simply eyeball it using a straight edge ruler.

5.  Arrange the elements for easy assembly (optional). 

To prevent confusion on which element is which.  Arrange all 10 elements on a flat surface and use a painters tape to tape down all the elements.  Peel the tape with the elements attached and set it aside for later assembly.

6. Assemble boom and element.

Starting from the tip of the square brass tube and the shortest element (Director 8).  Insert all elements through the square brass tube.  Do not worry about centering or straightening the elements for now.  It will be dealt with during assembly and bonding.

7.  Insert bonding agent.

Insert 1 or 2 strands of wire solder through the length of the boom.  Leave about 5mm on both ends of the boom for slack.  Bend the ends to prevent it from slipping through the boom.

8.  Center the elements.

Using a small straight edge ruler, measure both side of the element and center both side to the boom.  Do this for all 10 elements.

As explained previously in step 3, if the boom were drilled precisely, the elements should fit tightly to the boom.  This should prevent it from moving until the wire solder inside the boom has been melted.

9.  Bonding the element s to the boom.

Secure one end of the boom on a metal vise grip or lay the assembled yagi on a concrete floor. Using a propane torch, heat the length of the boom.  Concentrate the flame on the boom element joints.  Spend at least 2 to 3 seconds per joint.  Let the yagi cool down and inspect every element for any loose joints.

WARNING:  Ensure you have waited enough cooling time before handling the yagi.

1.  Building the gamma strap holder.

Using the 9/32 x 4” Hot Melt Glue Stick and a drill press with 3/32” bit attached.  Drill 2 holes across the glue stick at approximately 5mm apart.  Cut the glue stick on both ends of the 2 holes at about 3mm away from either end of the 2 holes.

2.  Cutting the gamma pipe.

Using the excess 3/32” x 4” Round Brass Tube that was used for building the elements and a straight edge ruler.  Measure and cut about 10mm of brass tube.  Clean cut both ends with a file and scrape off any sharp edges on the inside circumference of the pipe.

3.  Cutting the gamma wire and the gamma shorting strap.

( 1 ) Cut off about 35mm of RG-172 coaxial cable; ( 2 ) Remove and discard the outer jacket and braided shield leaving the inner jacket and conductor; ( 3 ) Remove 15mm of inner jacket revealing the inside conductor; ( 4 )  Finish by cutting off 13mm of the conductor.

Use the 22mm inner jacket and conductor as the gamma wire and the 13mm conductor as the gamma shorting strap.

4.  Assembling and mounting the gamma match.

( 1 ) Bend the gamma shorting strap creating a squared off u-shape and insert it through the 2 holes on the gamma strap holder; ( 2 ) Insert the gamma pipe through one of the hole on the gamma strap holder making sure that there is contact between the outer part of the gamma pipe and the gamma shorting strap; ( 3 ) Insert the other hole of the gamma strap holder onto the driven element of the yagi making sure there is contact between the outer part of the driven element and the gamma shorting strap; ( 4 ) Finally, insert the gamma wire through the gamma pipe with the 2mm of conductor on the gamma wire just sitting on top of the boom.

The 2mm of conductor on the gamma wire will be used as the feed point for the yagi.

1.  Drill the shield feed point.

Drill a 3/32” hole  on the boom about 5mm behind the driven element.

2.  Prepare feed line.

( 1 ) Strip off about 15mm of the outer jacket of the coaxial cable; ( 2 ) Separate and twist the outer braided shield from the center conductor; ( 3 ) Strip off 12mm of the center conductor jacket; and ( 4 ) Apply some solder on the twisted outer braid.

3.  Attach the feed line.

Insert the twisted braided shield to the 3/32” hole on the boom and solder.  Flip the coax cable to the other side of the boom and secure with tie wraps. 

( 1 ) Align the center conductor of the feed line to the gamma wire; ( 2 ) Solder the tips together;  ( 3 ) Cut off the excess tips of the center conductor; and ( 4 ) Apply some hot glue to prevent it from touching the boom.