Tower and TH6 raising at VK3PDX QTH
I shifted from Traralgon to Tinamba almost 3 years ago, in Traralgon I had a Nally tower with a TH6 atop and a detached flat for a radio shack(3 rooms inc. toilet), but no rotator, except for Mr Armstrong.
RADIO SHACK AND TOWER IN TRARALGON.
Having moved to Tinamba I began the slow process of rebuilding my amateur station, this started to come along when an opportunity came up to buy the house next door, this was on a block and a half with a 2 hectare paddock-just fine for amateur radio, so we moved again. Once we had done all the important things associated with a shift I again began to re-assemble my radio shack and tower.
Tower on ground in Traralgon and prior to drop.
The Nally tower has, in its self, an interesting “history”. I purchased the tower from another amateur, Barry -VK3BDG, in Mirboo North, along with Peter VK3NPI, we moved the tower to Traralgon and eventually put the tower up. Through circumstances we moved to Tinamba, and so did the tower
Before leaving Traralgon I had acquired a replacement in ground section from a local fabrication shop for the price of a box of beer, a fair exchange I thought!
I now had to get it joined, as it happened, the people we sold the first Tinamba house to was a welder by trade, he was able to roll a joining section for the tower and, on Xmas eve, welded it together.
.
Tower pole in ground outside shack,
Tinamba.
Next I had a hole augured into the ground using a local contractor, and a few weeks later, stood the pole in the ground and poured the concrete.
Next I needed to
1) fix the TH6,
2) buy a rotator,
3) make a base for the rotator,
4) get new coax,
5) Do 100 other thing to get ready to raise the tower and get the antenna in the air.
The next photo shows the condition of the trap covers on the TH6, I wanted to improve on this and try and make them bird proof!
Damage to traps caused by bird attack. . Finished trap cover
After some thought I took a 2 pronged attack, first I strengthened the trap caps and then make it more difficult for the birds to attack them. The first I achieved by using a very strong and thick heat shrink product (Butyl heatshrink), and secondly I protected the traps by spiking them with cable ties, hoping that both of these things wouldn’t effect the performance of the traps too much.
Heat shrink on traps. Protecting traps from bird attack!
Once the TH6 had been prepared, which was prior to the tower raising day, we had a number of other things to prepare on the day, first was the base mount for the rotator and secondly a thrust bearing to take the weight of the antennas, and allow the rotator to do the job of just turning the antenna array.
The rotator came with a template for the base mount, but this was slightly inaccurate, it also did not allow for centring the rotator, so the fixing holes in the base plate were elongated to allow this to happen, next the base plate was welded to the tower.
I also had to find approximately 20 meters of 8+ core cable for the rotator controller, and join the cable to the plug and socket, and then test the connectors by metering, and then the real test-connection to the rotator and a bench test. This worked first time.
I also decided to use as low a loss coax as I could afford (get away with) so I sourced and purchased 2/3rds of a roll of Belden RF400, although I am yet to buy the appropriate connectors, currently using PL259’s.
Welding rotator base plate to tower.
Once this was complete a thrust bearing was put in place, this I decided to do by simply making a collar to fit around the mast tube and then I used a piece of scrap switchboard material, which was flat, smooth and impervious to water, as a “bearing” between the base of the collar and the top plate of the tower. The advantage of this arrangement over a conventional bearing is that it requires no lubrication, it is self cleaning and has low frictional resistance. (That’s what I hope anyway).
Mounting
lattice section on tower base.
We utilised a neighbours tractor lift the lower tower section into place; it made the task very simple and very safe, as the load was steady and secure.
Once the tower and associated hardware attached (winch cables, inner section etc), we were able to centre the rotator and attach the mast pole. For a mast pole I purchased a 4.9m length of thick walled scaffold tubing, perfect for the job, this came from a local metal supplier, after some phoning around and bargaining!
The next task was to assemble the TH6 and attach it to the tower, a difficult job as it is a large antenna and requires many screws, nuts and washers, as well as ensuring that all the elements are in the correct position and at the right length. I had previously measured and fitted all the elements together.
REBUILT TH6 ELEMENTS. ATTACHING TH6 TO TOWER
After getting it all in the air, I took it all down a few days later in order to birdproof all the coax on the TH6, as I had used RF400 coax, which is not inexpensive, I did not want to have the birds make a meal of it. On the top of the mast pole is a dual band J pole constucted by Mike, VK3XL, which I am testing, the tower will also eventually support a 2M and 70CM yagi.
The above pictures show the bird deterrents used on the cables and traps.
The last photo shows the TH6 atop the tower.
I would like to thank some of the people who encouraged me with this project, first off my wife Nelly, who may now have second thoughts about the radio shack. Peter VK3NPI and Mike VK3XL for months of egging on and much help and assistance on the day and George VK3GWK. Two others who also assisted greatly were my neighbours Graeme and Craig.
(All material remains in this article the property of David Helyar, applicable copyrights apply. Material can be reproduced with permission of David Helyar.)
David Helyar VK3PDX, PO Box 123 Tinamba. gravesend@vic.australis.com.au