Hi all I would like to get some info on the loading capacity of what I think is a 20 meter Southern Cross Tower.
It is at Mt Cotton and was Motorola Repeater site.
The (Brisbane) Bayside Club now has the use of the tower and we have a number of great projects on the go but I am concerned about the capacity to keep the antennas up in the air. I have emailed the agents in WA but as yet haven't heard.
Can anyone help.
Keep in mind that these things used to have a set of large rotating sails on top in their original role as windmills. That represents a very significant wind loading, far more than a number of VHF or UHF antennas will create.
This Forum is only going to be as interesting as the posts it contains. If you have a comment or question, post it as it may trigger or answer the query in someone else's mind.
I thought Southern Cross Antenna tower. was a specific design and different to what was used for windmills. I could be wrong, not 100% sure.
I have a 20m Southern cross antenna tower here.
I have tried to take a screen shot of some older information here -
I know that I visited their web site a few years ago but can not find it now. What I did find however is some scanned documents here - http://vk5pj.com/towers/sth_x_info.htm
I seem to recall that they also fabricated other products such as tank stands. Found them here... looks like they have grown and narrowed their product focus - http://www.southerncross.pentair.com.au They may still be able to provide some information from the archives if contacted, however.
I don't think they had a special version for radio applications.
Years ago I had a tower put up for a microwave terminal for a remote HF site I was setting up. For this they supplied a standard four legged tower normally used to support a water tank.
I've attached a scanned copy of the information that I have on the Southern Cross KVD structures.
As can be seen from the last page, the company used to manufacture towers for a variety of applications, however the KVD series were intended to be used as antenna supports.
For the history buffs, the history of the Toowoomba Foundry where the towers were made can be found here.
Thanks all for the info,
I have a layout that we propose but not sure of the loading.
I would appreciate it if you would give me your opinion of the loading or if you can direct me to any engineering info so I can get an Idea if this is over the top.
There are specific 'windmill' and 'radio' tower version, do not be fooled into thinking there is only One. Mine at home is a 'KVC' model, there was a later 'KVD' model, I have never been clear as to what the differences were.
Windmill towers have a much wider base on them to deal with the windmill windage at the top and do not go much over 40' in the old money (there were exceptions to this rule however) and their cross bracing was lighter than the radio towers as the radio towers needed to be more rigid in constrcution.
The 'radio tower' version was used extensively around OZ by government and commerical companies and is much narrower than the Windmill tower and has more bracing on its sections plus was commonly available up to 80' in height or special orders to over 120'
hope this clears it up... if someone says they have a southern cross tower, you NEED to ask which one they mean, the windmill towers WILL twist slightly as it is part of the design to absorb the stress of wind gust and the mill head swinging around in the breeze.. be wise be informed.
looks like they have grown and narrowed their product focus - 