ZS2EZ TOWER PROJECT
The greatest dream of any Amateur Radio operator is to have an imposing antenna tower topped with large antennas. Since embarking on the adventure of HF in 2005 I have been using a 9m (30ft) high antenna tower, and have longed for more height. When I acquired my WARC band beam, I dreamed of being able to stack the two antennas on a high tower. Finally this looks like becoming a reality during 2010!
In 2008 my friend Donovan ZS2DL obtained a Webb "Galaxy" tower that had become surplus at a local Military base. This tower comprised three 6m long sections and a 3m tapering top section. Upon deciding that this tower would not be suitable for his location, Donovan offered this tower to me for free, provided I arranged collection. Enlisting the help of my friends Glen ZS2GV and Basie ZR2BA, I arranged for collection using Glen's trusty Isuzu LDV, and the tower was transported to my house. As our municipal regulations do not allow a tower to exceed 15m (50ft) we dropped off one 6m section at Basie's home along the way. This left me with two 6m sections and the top section.
The tower sections stored in the back yard of my house
As the top section of the tower tapered to a point, this made it impossible to fit an in-tower rotator and mast. Basie ZR2BA offered to modify the top section for me, by cutting it and fitting two thrust bearings and a rotator mounting plate. Glen ZS2GV provided a thick-walled 6m pipe that will rise from the rotator through the thrust bearings and support the two Cushcraft beams.
Months dragged by as I tried to determine where I wanted to erect the tower, and pondered on how the tower would be raised. Finally in late 2009 a decision was reached, and I began to look at getting the project under way. The first step was to get a base support "cage" assembled. Basie ZR2BA stepped in, and in February delivered the base assembly cage. Glen ZS2GV and his assistant Elton assisted with the digging of the hole - an impressive 1.1m X 1.1m wide, 1.2m deep pit alongside where my WARC band beam currently stands. A copper strip (provided by Andre ZS2ACP) was buried around the perimeter of the hole, with a lead attached for connection to the earth spike. A wooden frame was assembled around the hole, and the base cage suspended in place, ready for the concrete to be thrown.
The hole with the base "cage" suspended
In preparation for the mixing of the concrete base, 3 50kg bags of cement and 2 tons of coarse crusher run were ordered, and arrangements were made for a builder to do the work on Saturday morning 6 March 2010. To my great disappointment the builder did not show up to do the job, and was unreachable on his cellphone the whole weekend. Glen ZS2GV then stepped in, and arranged for his helper Elton do do the job on Saturday 13 March.
The 2 tons of crusher run ready for the mixing of the concrete base
Another view of the hole and base "cage".
(The WARC beam support pole is visible in the background)
The slight angle of the base in the hole is deliberate - the tower will need to clear 3 satellite TV dishes mounted on the side of the house alongside where it will be raised.
As planned, on Saturday 13 March 2010 Elton arrived to mix the concrete for the base. This landed up being a much bigger task than anticipated. The 3 50kg bags of cement did not go very far, and a further 4 bags had to be purchased!
Elton Mixing Concrete
The concrete was mixed to a strong consistency - 4 barrowloads of crusher to a bag of cement. It very soon became apparent that the full 2 tons of crusher would be needed
As we reached the end of the crusher, we discovered that we were still a bit short - 6 bags of cement ant 2 tons of crusher had not completed the base! Fortunately we had a quantity of fine crushed stone in elsewhere in the garden, and 4 barrowloads of this fine stone was mixed with the final bag of cement. This worked out well - the base now has a smooth finish and levelled out just as we had hoped.
The completed tower base
Finally after a little more than 2 tons of gravel and 350kg of cement, plus around 5 hours of heavy labour the tower base was complete. Now it must stand for a few weeks whilst the concrete sets properly. Phase One of the tower project is now complete.
The tower base after setting for a few weeks
The next step involved the re-engineering of the top section of the tower. This was completed by Basie ZR2BA, and was delivered during March.
The top section now has two 50mm thrust bearings fitted, and has a plate which will hold the Yaesu G-1000C rotator.
The re-engineered top section of the tower
Once raised, the tower will hold the Cushcraft A3WS with 30m addon kit at 60ft and the Cushcraft A3S with 40m addon kit at 50ft. There will also be a Diamond X50 dualband collinear above the A3WS (at 60ft), a 145MHz folded dipole two-stack, a 435MHz dipole, a 70MHz folded dipole and a 50MHz end-fed dipole mounted on the tower. It is ultimately planned to install an AlphaDelta DX-A Twin-sloper for 80m and 160m off the tower at around the 45ft mark, but initially an 80m dipole will occupy this spot. All antennas will be fed with LMR400 cable or 1/2" hardline (kindly supplied by my good friend Gavin ZS6GAV) and run through lightning arrestors before entering the shack. All antenna installation will be done to professional standards.
Further planning is to move the existing 9m lightweight tower from it's current location to the corner of the shack building, where it will support my 50MHz M2 6M7 antenna, as well as a 70MHz beam. A 145MHz beam will occupy the spot vacated by the 6m beam.
More to follow as the project progresses....