M2 2M18XXX Yagi (Courtesy M2 Antenna Systems, Inc.)

This post is about the assembly of the second of our four Yagi Antennas – the 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. Due to its size, I opted to assemble the 2M18XXX outdoors near the tower.

2m Yagi Parts

The first step was the assembly of the boom. I used the 2 foot high sawbucks 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.

2m Yagi Boom and Elements

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.

2m Yagi Element Layout (Courtesy M2 Antenna Systems, Inc.)

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.

2m Yagi Driven Element

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.

2m Yagi Boom Support Truss

Here is a picture of the completed 2M18XXX. It is a very well-built antenna and it should perform well once it is installed at the 110 ft + level on our tower.

Completed 2m Yagi

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.

You can read more about our tower project via the articles which follow:

• First Tower Part 1 – Ground Broken For New Tower!
• First Tower Part 2 – Tower/Antenna System Design Details And Equipment Ordering
• First Tower Part 3 – More Excavation For Feedline Conduits
• First Tower Part 4 – Tower/Antenna System Analysis And Design (Planning And EZNEC)
• First Tower Part 5 – Tower/Antenna System Analysis And Design (HFTA Analysis)
• First Tower Part 6 – We Have A Tower!
• First Tower Part 7 – 100 ft Tower Completed!
• First Tower Part 8 – VHF/UHF Antenna System Design
• First Tower Part 9 – Feedline Conduits And Electrical Power Complete
• First Tower Part 10 – Building Yagis (70 cm)
• First Tower Part 12 – Building Yagis (SteppIR DB36)
• First Tower Part 13 – Building Yagis (SteppIR DB36 Continued)
• First Tower Part 14 – Building Yagis (SteppIR DB36 Continued II)
• First Tower Part 15 – Building Yagis (SteppIR DB36 Completed)
• First Tower Part 16 – Building Yagis (Second SteppIR DB36 Completed)
• First Tower Part 17 – Feedline Breakout System
• First Tower Part 18 – Antennas On The Tower (Preparation and Upper Yagis)
• First Tower Part 19 – Antennas On The Tower (System Integration)
• First Tower Part 20 – Antennas On The Tower (System Complete)
• First Tower Part 21 – Antennas On The Tower (Final Odds and Ends)
• Complete Presentation on Amateur Radio Station Design And Construction

– Fred, AB1OC