Yesterday was an overcast and rainy day, perfect for antenna work since it wasn’t that hot.
I was able to complete one of the items on my list of improvements, which was to remove the 40/30m dipole and to raise the Spiderbeam a few feet higher. I was also able to renew the coax feed to the beam. I had been using a length of LMR400 that was given to me by K1PT a couple years ago – after it had been on his tower for several years.
For my antenna mast, I use something readily accessible on Guam – Schedule 40 galvanized pipe. I have a weight allowance every time I transfer, and exceeding the limit would cost me many thousands of dollars. My wife and kids are very thankful that I allow them to pack their clothes instead of tower sections – so I improvise.
Water pipe telescopes nicely, except for 1.25″ to 1.5″. There is an interference fit of a few thousandths. As a result, I telescoped 1″ into 1.5″ into 2″ pipe. This got me 28ft to the rotator, plus a few feet of aluminum mast and the Spiderbeam is at 35ft.
To keep the much smaller 1″ pipe from fitting sloppily in the 1.5 inch size, I cut and slotted two rings of 1.25″ pipe, which I then pressed over the 1″ pipe at the bottom and 2ft from the bottom. With some grinding, I was able to make a nice fit to remove the slop. Unfortunately I don’t have a photo to share because it was raining when I had everything taken apart.
To extend the antenna higher, I bought a 10ft length of 1.5″ pipe for the bottom section. Being conservative, I pushed the 2″ pipe up 6ft, pushing the Spiderbeam up to just over 40ft high. I also renewed the guy ropes – guying is a must. I like to use parachute chord, which is inexpensive, rated to 550lb breaking strength, and handles the sunlight (UV) well. I’ve had the mast up for over a year at the old height, and I had no sign of problem in 30MPH winds. This is usually the maximum we see here unless a tropical system is nearby, and in those cases the antenna and mast would be taken down for safe keeping.
I drilled small holes every 12″ in the smaller pipe sections and every 6″ in the large 2″ pipe. This allows me to slip a small 1/4″ bolt into the hole, so I can rest, relocate the pipe wrench, and lift again. This way, I can raise and lower the antenna myself in about 10-15 minutes. Once a pipe section is pulled all the way up, I use a large through-bolt to lock it in place. Like climbing a tower – I always use two bolts so one is always in place at any time, so it won’t come crashing all the way down if the wrench slips.
In the above image, you can also see the rats nest of para cord and ratchet straps I use to fix the bottom piece of pipe in place. No holes are allowed to be drilled into the house – when I move there will be no evidence of the antenna aside from the concrete base which is mostly buried.
I feel much better now having taken down the mast extension and the 40/30m dipole. KL9A teased me, saying I gained a full 0.1dB of improvement by raising the antenna 6ft. I would like to think I gained more. Perhaps going from 120 to 125ft is not much of a difference, but 35 to 40ft should help, especially on 20m. I did notice an increased noise floor – probably related to the new coax run – I will have to confirm once I repair my MFJ-259B and test the old LMR-400 for loss.
I’m thinking that I may not put the dipole back up at all. I’ll have to experiment and see. I have a new neighbor moving in next week (which was unexpected), and like the uncluttered look. I don’t want to press my luck with the housing manager. The vertical was equal to the dipole into Europe and North America, so I don’t think I’m losing anything if I don’t put it back up.