This post is about the assembly of the second of our four Yagi Antennas – an M2 Antenna Systems 2M18XXX. This antenna uses 18 elements on 2M to provide approximate 17 dBi gain in a very tight pattern. It is designed for weak signal and EME work on the 2M band. The specifications for the 2M18XXX are as follows (Courtesy M2 Antenna Systems, Inc.):
I began by doing a careful inventory of all of the parts for the antenna and gathering the necessary tools for assembly. I also took some time to carefully read the excellent instructions provided by M2. Due to its size, I opted to assemble the 2M18XXX outdoors near the tower.
The first step was the assembly of the boom. I used the 2 foot high saw bucks that I made for the purposes of building our yagi antennas. A set of carpenter’s clamps were used to hold the boom in place on the bucks during assembly. The installation of the elements was next.
This step takes some time as each element has a different length and must be carefully centered on the boom. To make this easier, I marked the boom with a felt tip pen to indicate the location of each element for easy cross-reference with the dimension sheet from M2 Antenna Systems.
Next came the assembly of the driven element and associated balun. The location of the shorting bars on the Driven Element Assembly is important in order to get a proper match between the feedline and the antenna.
The 2M18XXX has a long boom (36 1/2 ft.) and requires a truss support. The picture below shows the boom truss support system after it is assembled. The standard mast plate and hardware supplied with this antenna by M2 Antenna Systems will accommodate up to a 2″ mast. We will be using a 3″ mast so M2 supplied a custom mast plate and a truss support that clamps directly to our 3″ mast. To make the antenna easier to test, I first assembled it with the 2″ hardware so that I could test it without attaching it to the mast.
Here is a picture of the completed 2M18XXX. It is an extremely well built antenna and it should perform well once it is installed at the 110 ft + level on our tower.
I am going to move onto the construction of the first of our SteppIR DB36 antennas next. I will provide a post covering this step of our project next.
– Fred (AB1OC)