Drill hole in center of second end cap (3/4") and run round steel 18" X 3/4" rod through the center. I purchased the rod at Menard's Home Center and it would also be available it Home Depot, Lowes or similar home centers. This is the bottom section and the center stake helps when setting up the antenna.
Drill a 3/4" hole near the bottom of one end of one of the 5' pieces of pvc pipe. After drilling the hole run one end of 17' of RG-58 coax through the pipe and out the hole. Crimp a SO-239 on this end. Crimp a PL-259 on the other end. The long end is run through the pipes before erecting the antenna as a coax feed. Alternately you can just run a long piece of coax to the top but I thought this was quicker and easier. I leave the coax in the bottom section and feed to the connector in the top when I assemble the antenna. You may find it easier to leave the coax in a coil and feed from the top through the bottom.
Install pipe coupling to one end of the pipe as seen above. Install a coupling to the remaining pipe as well. The couplings need not be glued... in fact I didn't glue any of the caps or couplings and they seem plenty sturdy for the purposes of the support mast.