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I finally ordered the new tower today.
- Thread starter Captain Kilowatt
- Start date
Well it damn well better be after all the work and $$$ that I have into it.
It won't be exactly as I want it in the end due to winter setting in soon but I hope to have the 6m yagi on it as well as a Cushcraft A3WS for 12/17m and the Explorer 14 for 10,15,20, and 40m and I will string a couple wires for 80m and maybe 160m before/during the winter. I can get by with just one feedline this winter if I have too as I am using the RCS-10 remote antenna switch from Ameritron. I eventually want the 6m yagi on it's own feedline as well as a spare one or two feedlines. Nothing will be buried this year but in the spring I plan to bury all feedlines and control lines for the rotator and switch going out to the tower.
Lots, and I mean LOTS, of wind and rain today so not much going on. I did however work out a few things with the mast. The 21 foot piece of 2 inch pipe I will use for a mast is only rated at 35,000 PSI yield strength which is not that great for such a long length. I worked on some numbers this afternoon and decided that I would leave the pipe the full 21 feet long. This will make it about 16 1/2 feet out the top of the tower. Inside this piece of pipe I will sleeve the 8 foot mast that came with the tower. This sleeve will be placed about 4 feet from the bottom and will be positioned about one foot below the tower top and extend to about 7 feet above the top. This will create a mast with a steel wall of 0.272 inches right at the critical point which is where the tower exits the top bearing and will reinforce the mast for 7 feet above the top. In this 7 feet of mast I will have the Ex-14 and A3WS antennas mounted so only the 6m beam will be mounted above the reinforced point and perhaps a small 2m beam later. Further to the 0.0272 inch steel wall I will also insert a 4 foot length of aluminum pipe I have centered on the top bearing to add another 0.12 inches of aluminum. Total wall thickness at the point that will see the most breaking forces will be 0.392 inches.Needless to say the mast will have to be jacked up or down due to the weight however I have that worked out as well.
I think.
I hope.
I pray.
I think.
I hope.
I pray.
Looks great CK and the mast seems like it will do what you have designed it to do. Heavy duty is not describing it correctly, built like a Sherman Tank is more like it.
A lot of thinking and planning went into this tower install. It will give you many years of good service. Pics look great thanks for posting them.
A lot of thinking and planning went into this tower install. It will give you many years of good service. Pics look great thanks for posting them.
You would be surprised at just how much drag there is at the end of 12-15 feet of mast.The largest antenna, the Ex-14 with 40m add-on kit will be about a foot above the top. It is about 8.5 sq. ft. itself. The AW3S will be about 6 feet above that and it is a little over 4q. ft, and the homebrew six element 6m yagis will be about another six feet above the AW3S and it is about 4 sq. ft. This leaves about 4 feet left at the top for a 2m antenna if I choose to put one up. I may install the 11 element yagi I have sometime in the future but that will involve resetting all the existing antennas on the mast. The tower is rated for 52 sq. ft. and I will only have about 19 sq. ft at the most however it is distributed over 17 feet of mast whereas the tower rating is speced with the total load less than three feet above the top. As heavy as things look it really is not that much over spec for what I am doing with it.
Good deal, and using thrust bearings will help the rotor with the turning of the yagi's.
With the antennas so close do you think it will effect the Performance or input impedance's?
I had a five element 20 meter mono bander 8' above the ta-33 that was reworked for 17/15/12 meters.
It severely effected the 15 meter impedance having that 20 meter mono bander in such close proximity. I do not know why but it had a higher impedance. I remove the mono bander and input impedance was good.
You did mention you are using a coax switch, if the deselected antenna is grounded maybe it will not be effected.
Just curious as to what you think about having that much aluminum so close together.
With the antennas so close do you think it will effect the Performance or input impedance's?
I had a five element 20 meter mono bander 8' above the ta-33 that was reworked for 17/15/12 meters.
It severely effected the 15 meter impedance having that 20 meter mono bander in such close proximity. I do not know why but it had a higher impedance. I remove the mono bander and input impedance was good.
You did mention you are using a coax switch, if the deselected antenna is grounded maybe it will not be effected.
Just curious as to what you think about having that much aluminum so close together.
I am just basing my spacings on what the manufacture states as the minimum spacing. Hygain says to space any other antenna at least 5 feet from the Explorer 14. On the other tower I had a Cushcraft A3 for 10,15, and 20m which is very similar to the A3WS for 12 and 17m. I had the six element 6m yagi only about 4 feet above it and neither antenna seemed to be adversely affected. I am sure there was some interaction however the SWR was good and the patterns were good as well especially the 6m yagi which was fantastic off to the side. What was 20/9 on the front was barely audible on the sides of the 6m beam. Since none of the antennas are for the same band interaction should be minimal however I understand the concerns about proximity. I can only do what I can do and cross my fingers. I also wonder about your reworked TA-33.If it still used the original traps but different tubing lengths to retune it for 12 and 17m then there may have been some interaction with the 20m monobander and the 20m traps on the TA-33.
BTW, the switch does ground out all unselected antennas.
BTW, the switch does ground out all unselected antennas.
The ta 33 was reworked for 10/15/17 just shorten the outside element to resonant it on 17. typo on my part. The yagis may have been 8' apart.
That interaction was the deciding factor to get the MosleyTH67B, one antenna and multi bands. I like the specs on the Mosley compared to a log periodic.
I basically did the same thing on my VHF tower in FL.
6 meter home brew yagi, 5' above it the 12 element 2 meter yagi and then above it the 2 meter vertical. I could only put so much mast up so I did the same thing you are planning on doing.
Put them in best I could and crossed my fingers.
Both yagi's worked fine, even if I did not have the ultimate spacing between the yagi's.
That interaction was the deciding factor to get the MosleyTH67B, one antenna and multi bands. I like the specs on the Mosley compared to a log periodic.
I basically did the same thing on my VHF tower in FL.
6 meter home brew yagi, 5' above it the 12 element 2 meter yagi and then above it the 2 meter vertical. I could only put so much mast up so I did the same thing you are planning on doing.
Put them in best I could and crossed my fingers.
Both yagi's worked fine, even if I did not have the ultimate spacing between the yagi's.
I spent the day today undoing most of what I did yesterday. While reinforcing the mast I drove the reinforcing sleeve inside the inner pipe from the wrong end and had to drive it out, fix up the shims, and put it all back together again.
It's funny how you can think about things like that while taking a bathroom break at 3:00am.
Seriously,that's when I thought about it. How I managed to realize I screwed up at that time when it didn't occur to me while actually doing it is testament to how much I am thinking this out I guess.My subconscious must still work on it while I am sleeping. Anyway I ended up measuring everything all over again and found enough extra pipe of the proper size to drive out the inner reinforcing pipe and put it all back together properly. In order to prevent the inner sleeve from dropping down inside the main mast I drilled two 5/16 holes at right angles to each other a few inches apart. I drilled straight thru both pieces of pipe and tapped the holes for a 3/8-16 thread. I then screwed in a 3/8 stainless steel bolt until the shoulder started to bind and then used a mini-grinder to cut the bolt head off and ground it smooth. This locked the inner sleeve inside the outer mast preventing it from dropping down as the mast flexed back and forth in the wind. It also allowed the mast to drop straight down thru the mast bearings without having bolt heads in the way. Next I enlisted the help of my two boys to help carry the mast, which must weigh nearly 100 pounds, the 125 feet or so to insert into the top of the tower. After it was slid down inside the tower and the mast bearings aligned and tightened I realized I had left an eight foot piece of aluminum pipe inside it from my efforts to remedy my mistake of the previous day.
I was lucky enough to be able to insert a heavy tape measure and use the end to snag the far end of the pipe and pull it out rather than take the mast back out of the tower and up-end the bloody thing to slide it out.
I also drilled and mounted the remote coax switch box on the top of the tower. Everything is ready for the crane truck tomorrow however the weather is not looking as good as it was yesterday. It is calling for 40% chance of showers which is not too bad with temps near 60 degrees. The bad part is the 20 mph winds gusting to 30 mph.
I don't mind climbing but this is a first time for this type of tower and I am not used to it and I chicken out real fast with any wind. In any event if the tower does go up I will have to climb it to unhook the hoisting straps. Wish me luck and a wind free day.
I hear ya on that one. If I ever have to climb with any wind I ALWAYS climb with the wind at my back. That tends to push you in against the tower and not away from it. Even if the wind is slight it is a reassuring feeling if nothing else.
sounds like a good time to invest in a nice 4 point harness CK
Got it with the two climbing lanyards with big gorilla hooks and a safety belt with seat harness. I have had them for years and they were well worth the investment.
Nothing quite that fancy. The outer 21 foot piece of 2 inch ID mast is a single piece of heavy schedule 40 water pipe painted with a heavy coat of cold galvanizing. It is sleeved with an 8 foot length of schedule 40 galvanized steel mast that came with the tower. This sleeve starts about one foot below the top bearing and extends 7 feet above the top of the tower. It in turn is sleeved with another piece of pipe that is four feet long centered on the top bearing. This means the wall thickness is 0.4 inches right at the point most vulnerable to bending, where the mast exits the tower. The bottom two antennas will be mounted on the mast where it is double thickness and only the 6m beam will be mounted above that point. The outer mast is just a tad under 2.5 inches OD. You will see lots of warnings about using water pipe for masts and it is true if using long lengths of unreinforced pipe, especially thin walled, but by doing what I did I have no worries whatsoever. I used to run a Wilson Shooting Star on about 16 feet of 2 inch OD water pipe on a hilltop and all it did was move a little in the gales. Sometimes a little flexing is better than nothing at all.