VE3CVG's 6m 5 Element Plumberís Delight (Almost) Yagi Antenna

I was not satisfied with the 6m 3 element 'Plumber's Delight' that I built using the ARRL Handbook as a guide, so I decided to build a 5 element antenna, and the results were more than worth the effort.

This 6m antenna is a modified version of a Tona antenna leant to me by a fellow ham. I could find next to no information available on the web about Tona antennas. The particular antenna that I experimented with was a real beauty to dismantle and reassemble - great for Field Day. I really liked this antenna so decided to clone it more-or-less. My antenna is not intended to be as portable as its original version but it could certainly be constructed to be quite portable.

Basically, you will need 5 ea, 10' lengths of 1/2" round aluminum tubing for the elements and 1 ea 12' length of 1" square aluminum tube for the boom. In addition, you will need a 4" x 6" x 1/2" piece of a white teflon cutting board (the type without grooves in it - available at Home Depot), 2 feet of 1/4" aluminum rod, some scraps of aluminum to make the match sliders, 4 ea 3"x 3" x 1/8" aluminum squares for mounting elements, a 5" x 5" x 1/8" auminum square for the boom to mast mounting, and some assorted stainless screws.

All round tubing elements were cut with a plumberís tubing cutter available at most hardware stores. The aluminum boom and rod, and the plastic/teflon can be cut with a sharp hacksaw.

The aluminum that I used is T6 hardness.

I purchased my aluminum at Ridalco, 1551 Michael Street (near St.Laurent and Belfast). Total aluminum cost was under $75 (incl tax) and could have been done for less.

The dimensions that I used are:

I used 1" square tubing for the boom because it is strong enough to take the weight without additional support arms, wires or braces. The elements are 1/2" round tubing and are fastened to the boom by attaching to 3" square plates using home made U-bolts.

The u-bolts are made from 6-24 threaded rod which is bent around a short post made of 1/2" tubing. You can fabricate this jig on a piece of 2"x 6" spruce. Drill the wood to snuggly accepts a short piece of 1/2" round tubing (leftover from an element). About 1/2" from this post made of tubing, drive in a sturdy 3" nail. Now to make your u-bolts, wedge the threaded rod between the nail and the tube with long part of threaded rod extending past the 1/2" tube. Carefully wrap the rod around the tube. When you get it pretty much to a U shape, thread the rod, with the U at one end, down a super-champ tool (for cutting screws), cut the rod at a point where the legs of the U are long enough to fit through a plate while holding the 1/2" tube. Fabricate enough of these u-bolts for the entire antenna (10 U-bolts). They are a little tedious to make but work very well.

The coaxial feedline connects to the two stainless bolts going through the teflon block, one on each half of the driven element, nearest the wooden dowel. Use soldered- screw terminal on a lead from the center conductor and from the shield. The feedline is fastened on the side farthest from the element.

The sliders are made from light aluminum stock which has been formed around the element on one end of the slider and on the rod at the other end of the slider. After forming, drill these and use 4-40 stainless screws and nuts to compress them and hold everything snug.

Be sure to coat the feedline several times with liquid tape (bright yellow can) available in plumbing section or electrical section of CTC. Also coat the wooden dowel with liquid tape to prevent moisture seeping in and shorting the antenna.

When adjusting this antenna, you should use either an antenna analyzer, or at least a radio with a very good SWR meter. I use both. You will have to experiment with the sliders on the driven element while watching the SWR. Once I got the sliders close to optimum, I was able to determine that the antenna was 300 KHz low so I cut an equal amount off each end of the driven element. About 5/8" solved the problem.

Closing Comments:

According to my MFJ259B, at 6 feet off the ground, the antenna presents a perfect match at 50.200 MHz and less than 1.2:1 for +/- 500 KHz from the centre frequency. It's better than 2:1 all the way up to 52.50 MHz and drops to 3:1 at 53.5.000 MHz. I have been fooled by my 259B so I always double check with a radio.

Mel (VE3OJN) put my new 6m antenna up at the 50 foot level on the tower, the first week in June, 2001. A picture of the antenna on the ground can be seen at The Infernal Tower pages (update).

The antenna was used in the June 2001 VHF contest and worked very well and the radio is happy with the match. I went through a period of time where the antenna seemed to be really noisy ... this proved to be an open shield and was eventually tracked down to a problem at a feedline connector. Since that problem was corrected, great performance.

I am keeping my vertical dipoles (slopers) for use with repeaters and experimenting when the band is open, but you can't beat a beam when the band is unco-operative.

If you found this information helpful or informative, please send me an email to encourage me to provide similar material in the future. Thankyou for visiting and please come by again.

 

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This page was updated on February 22, 2008