This tower started out as a television antenna tower at Second Valley but with the introduction of digital televison it was no longer being used. My friend "Bob the Builder" discovered it while working in the area and it was soon laying on the ground in my back yard. My knee operation October 2012 held up progress for almost a year but I did manage to undercoat it with () and top coat it with () and eventually fit the four antenna. The HF antenna is a Tet-Emtron TE-33, the 14 element is a rebuilt ATN antennas fourteen element 70 cM, the 2 Metre is a VK5TR/VK5JST three element yagi and there is a 70 cM J-Pole poking out the top. This was on the back of the house but from that location it would not make it in to the NERC 70 cM repeater, I am in a dead spot for 70 cM because of the hills between me and the repeater site.
Looking at the photos you will see I have made good use of nylon cutting board material to make the two bearing assembles. Before the tower went up I painted the nylon because I do not know how UV stable this is. The control box at the top of the tower has a coaxial relay to switch the 70 cM feed line between the yagi and the J-Pole.
Many thanks to the boys from the North East Radio Club for turning up at my QTH after our coffee meeting on Wednesday the 11th Spetember 2013 to help me with my "errection".
When the tower was up in the air I checked each antenna with my miniVNA and other antenna analysers and I found the three element tri-band was in trouble, the characteristics were not like those published in the documentation. I should have been able to use this very well made antenna without an antenna tuner as the SWR never rises above 1.5 to 1 accross each of the three bands it is designed for and is very close to 1 to 1 in the band centres. I emailed Mark at Tet-Emton and a few days later he phoned me from Western Australia and we both came to the conclusion one or more of the traps were faulty. This antenna was erected about 2006 in a suburb near the sea and the work was done by a contractor as it was an insurance claim. I suspected the traps needed some attention after being up in the air in such an environment for a number of years. The fellows from NREC came around again one wednesday after our coffee morning and we had an un-erection, folding the tower down to the ground with an electric winch.
Some weeks later I measured each of the traps and one was open circuit. I opened each trap, took out the screws and flat washers that terminated the coils and put the screws back with stainless steel star washers and a dob of Inox grease on each connection. The DC resistance of each trap was npow the same. One day soon we will have another erection and put the tower back up in the air. I learnt a lesson from this exercise, just because an antenna has been in use for a number of years it does not mean it is still performing as the original design intened, I should have checked the traps before we hoisted the tower into the air. If you have a tri-band trapped beam, have you checked it with an antenna analyser recently ?.
While I had the tower up in the air for that few weeks we had very windy weather and I found my attachments between the top tube and the tube that comes down the tower, and also were this tube is clamped by the rotator, was not adequate so the tower had to come down for modification anyway. I had also installed an camera on the end of the beam and this was a second hand item from a friends Motor Home and it had seen better days. I have removed this and put a light on the end of the beam so I can check which way it is pointing on very dark nights.
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Written by and Copyright, Phil. Storr © Last updated 9th November 2013