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Homebrew

Antennas

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Portable 3 Element Cubical Quad

                                    Material List
1) 1x Boom- 50mm square extruded aluminum, 3.14 meters
2) 1x Large U-Bolt
3) 12 x 20mm PVC electrical conduit @ approx 2m long
4) 6 x 16mm OD aluminum tubing @ approx 600mm long
5) 12x 20mm hose screw clamps.
5) quite a lot of electrical copper wire, the thicker the better.
6) a 1:1 Balun
7) whatever else is needed when the time comes.

 

fig-01 the 50mm square extruded aluminum @ 3.14m

(left over length from renovations on verandah)

fig-02 One long U-Bolt clamp with pipe bracket

fig-03 20mm PVC electrical Conduit (Bamboo is hard to get)

fig-04 20mm PVC electrical Conduit (for the spreaders)

fig-05 Find the center of the boom @ 1.57m & mark your center line. (c/l = center line)

fig-06 I decided (after a beer & some thinking) to mount the boom to mast section towards the back from the center line. That would give me nearly equal spacing of the elements.

fig-07 marking for drilling bracket holes. 1st hole is 10mm back from c/l, 2nd hole is width of the U-Bolt, here it is 75mm. So 2nd hole is 85mm back from c/l. (The director to driven spacing is 15mm shorter than reflector to driven. Otherwise, nothing to worry about.)

fig-08 measure forward 15mm from c/l. This is for the 1st spider of the PVC spreader. Remember that I'm using 16mm OD aluminum tubing, which the PVC will fit over quite nicely.

 

fig-09 the 2nd spider is on the same side as the mast bracket, it gives you room to tighten up the nuts on the U-Bolt. Measure forward 32mm and mark it. This is for the second spider. There is a 1mm spacing between the 2 spiders inside the boom. Make sure ALL the spiders on this side are marked forward of the other side. This is to keep the spacings even.

fig-10 Now for the Reflector. Measure back from the edge, 20mm. Mark it. (make sure you are using the side that does NOT have the clamp on it) Next, rotate boom 90 deg and measure in 37mm, mark it.

fig-11 With the Director, use the SAME procedure as the Reflector.

Fig-12 The holes for the U-Bolt mast clamp have been drilled.

Fig-13 The mast clamp is put in place.

Fig-14 The locating pilot holes have been drilled ready for the 16mm hole saw.

Fig-15 The 16mm holes have been cut. These are for the Driven Loop.

Fig-16 16mm holes cut on both ends, for the Reflector & Director loops.

Fig-17,18 The 4m lengths of PVC conduit been cut into 2m pieces.

Fig-19 The aluminum spiders for the PVC spreaders @ 650mm in length.

Fig-20,21 Find & mark the center of the aluminum spiders for drilling the locking screw holes.

Fig-22,23,24,25,26 Mark out & drill the locking screw holes in the boom. Insert the aluminum spider, using a 25mm self tapping screw, secure the aluminum spiders to the boom. When it is time to pack up, just unscrew the screws & slide out the aluminum tubing to be packed away for transport.

Fig-27,28 With a hacksaw (metal saw) or a thin bladed saw, cut 4 slots @ 30mm long into one end of the 2m PVC conduit. Attach the 20mm hose clamp. When the clamp is tightened, the PVC is held securely to the aluminum. It is also easy to undo so the quad can be pulled apart for transport.

Fig-29 Three (3) of the spreaders attached to the boom.

Fig-30,31,32, I'm using an old 240VAC extension power lead for my loop wire. With a sharp knife, I stripped of the outer protecting casing, leaving the 3 inner wires, green/yellow- earth, brown-active & blue- neutral. my 3 wires for the 3 loops.
Green/yellow - The Reflector Loop was cut 11.434m (+10mm for soldering) long, then with a marker pen, I marked of the lengths of 1 side of the loop, 2.858m. 10mm of each end was bared for soldering into a loop.
Brown - Driven Loop was cut 11.157m (+10mm) long, then with a marker pen, I marked of the lengths of 1 side of the loop, 2.789m. 10mm of each end was bared for attaching to the 1:1 balun.
Blue - Director Loop was cut 10.824m (+10mm) long, then with a marker pen, I marked of the lengths of 1 side of the loop, 2.706m. 10mm of each end was bared for soldering into a loop.

Fig-33 I put a small slot in the ends of the PVC spreaders, to hold the wire loop. The reason I marked off the loop sides with a marker pen is to make it easy to locate the corners of the loop onto the spreaders.
The spreaders are then slid out on the aluminum tube until the loops are extended. The aluminum tube between the spreader & the boom should be all equal in length.

Fig-34 The 1:1 balun on the driven loop.

Fig-35,36,37,38,39 The finished quad, ready for work. The 3 element quad is going to be used for my portable DX'Pditions. I hope this little quad making epic has helped you with the construction of a quad.

A good success story, the 3 ele quad worked extremely well. One of my portable DX spots, 'The Log Dump', up on the Barrington Tops. This was the first test & tuning weekend. I worked props from all around the world. Pics were taken the weekend of 24th & 25th of Nov, 2007.

With all the talk about Cubical Quads lately, I decided to build a portable model. The criteria was that it could be put together easily & taken apart to be packed away into a small package to fit on car or trailer roof racks.

So I grabbed a beer and started looking around the yard & under the house. I came across some 50mm (2 inch)square aluminum extrusion, it was left over from the back veranda make over. It's length is 3.14m (10.3 feet), mmmm I thought, thats close enough to make into a 3 ele quad. So without using the quad formulas for the loop spacings, I threw caution to the wind and grabbed another beer & set up my portable antenna shop.

I grabbed my new digi camera (and another beer) to document the making of this quad, which I called ""The Portable 3 Ele Cubical Quad, Model PWE-144"" This documentary is to be photoed over the next month or so, as I scrounge up bits & pieces for the quad & throw it together. (look for & find parts for the quad)

The following photos & notes are the first part of this epic quad building journey. As I said at the start, I'm using spacings that suit the length of the boom, not using the classic quad formula for spacings. One of two things are going to happen after it's finished. 1) it's going to be a lemon and not work or 2) oh my god, it works. So we won't know until we give it ago. The loops will be made with the quad formula.

This antenna might not work (I think the spacings are too small), but the main reason I'm doing it is to show people how to make up a cubical quad, although you would use the dimensions from the quad calculator. Thats why I photographed the manufacturing stages.

The Story Of My Portable 3 Element Quad

Saturday, August 18th, 2007

Log Dump Success Story 30 Oct-2 Nov 2009. Managed to work some EU, 224, 176, 17 & 41 div, with the 3 Ele Portable Quad. The tower setup worked extremely well.