Assemble the 6m LFA Yagi

Introduction

Cooper elements for a 6m three element LFA Yagi Antenna (aka LFA Yagi-Uda Antenna) have no use until secured to a boom.

This post completes our construction notes for the LFA Yagi made with copper tubing.

LFA Yagi Antenna Materials

Copper pipe element construction was covered in previous posts.

The boom mounting materials use PVC plumbing tees with a PVC pipe glued in to strengthen the holes which hold the copper pipe elements onto the boom. This inspiration for this technique came from K5DIY featured on Justin’s 6m web page.

An 8 foot aluminum pipe serves as the boom for this 6m LFA Yagi.

A boom/mast plate from DX Engineering holds the boom to my aluminum mast.

A three foot wood dowel reinforces the break in the copper at the loop feed point.

LFA Yagi Assembly Photographs

8 foot aluminum boom arrives via UPS — Aluminum Boom

LFA Yagi Element Arrangement — LFA Layout

PVC Tees used as element holders — PVC Tee Element Holders

Pipe used to reinforce PVC Tee — Reinforcement for PVC

Use vice-grips to crimp copper pipe — Vice-Grips

Pipe after gentle crimp using vice-grips — Crimped Copper Pipe

Pipe just balances on Tee — Balancing Tee

Use a pencil to mark centerline to center in PVC tee. — Center pipe in tee

PVC Tees on Driver Loop

Cut 1/2 inch of copper pipe at loop feedpoint. — Feedpoint Cut

Hang tees on boom to check things out. — Test fit components

The loop gap requires reinforcement. — Feedpoint stiffener

I found out tomato stakes are conductive - oops. — Oops – Metal Stake

Opening the tomato stake reveals conductive metal we don't want across the feedpoint. — Not good

A wood dowel will have to do for now. — Wood Dowel

Insert wood dowel and center between both side of feedpoint. — Insert Wood Dowel

The yard long wood dowel supports each side of the feedpoint copper pipe. — 3′ Wood Dowel

Drill two holes through copper into wood and use wood screws to attach coax. — Holes for Feed

The wood dowel holds the screw fast. — Tighten Wood Screws

Completed LFA loop feedpoint with coax directly attached. — LFA Loop Feedpoint

Elements on boom, the LFA is ready to clamp tight and use. — Complete LFA Assembly

Conclusion

Well, it appears I now have a functional field portable 6m three element Yagi-Uda beam using LFA techniques. I’ve only used it once during KX4O Field Day 2012 (Link below), but no Magic Band openings were found like in 2011.

I’ll try it out during a VHF contest for more aggressive testing and report the findings here.

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1 thought on “Assemble the 6m LFA Yagi”

Thanks very much for the extensive and useful article; I'm chomping at the bit; just finished a 6m j-pole. Couple of questions. I assume that in the "cutting" article when you said, "Test fit then solder" you omitted first slipping on the tee on one leg? The feed point tee can be added later as the pipe is to be cut.

What diameter boom did you use? Fittings? What type of copper pipe – the I.D.s are different.

Thanks, Christian KD2LIN