The six spreaders are made from fiberglass tubing purchased from Max-Gain Systems.
To avoid extra costs for shipping 8' poles, I paid Max-Gain to cut the tubes into 4' sections and made simple joints to link them together. Each spreader consists of three tubing sections. The bottom third of each spreader is 3/4" tubing, while the middle and outer sections are 1/2" tubing. The joints are two types - if one tube slides into another, it is a simple 1" tube section glued onto the smaller tube to prevent it from sliding too far together. If both tubes are the same size, the joint consists of a short section of larger tube overlapping both sections, plus another short piece as a block.
My spreaders evolved as I built the antenna. The first attempt used 1/4" solid rod for the outer spreader section, but that doesn't have enough strength to give the 20m wire enough tension. At that point, I already had built the base and clamps for 3/4" tubing, so I bought more 1/2" tubing to replace the 1/4" rod plus one additional 3/4" tube to make the joints. If I was going to do this again from the start, I would use 1/2", 3/4" and 1" tubes, with 4' sections of each.
The lower junction between the 3/4" tubing and 1/2" tubing was made by cutting a short 1" chunk from the 3/4" tube. This was pushed onto the 1/2" tube about 6" up from the end and glued in place with epoxy. This allows the smaller tube to slide into the larger one up to the block.
For the joint between the upper two 1/2" rods, I cut a short (about 8") section of 3/4" tubing and glued it 4" onto the middle tube. I glued another 1" block onto the outer tube so it would slide into the middle and stop. As things worked out, the 17m antenna wires ended up clamped right at the top of this junction.
