[TowerTalk] re Trapped Tribanders Turned Vertical

[Peter Forbes]

Hi,

Whilst the esoteric discussion on vertical versus horizotal polarisation is interesting, the main focus of the original question seems to have been lost.

Mounting a traditional tribander in a vertical poistion is going to present one particular problem that needs to be carefully addressed.  That is the problem of water buildup in the traps, particularly after a few months when dust and insects have had a chance to enter the traps.

Usually traps mounted horizontally have several drain holes facing downwards, whereas traps designed for vertical mounting will have a series of drain holes at the base of the trap.

Using  traps designed for horizontal in a vertcal position will be particulary susceptible to water entry, especially if the holes face in the direction of the prevailing winds (hard to predict as the beam can be turned anyway).

Adding some additional drain holes to one end of the traps will need to be done carefully, so as to not interfere with the way in which the outer tube cover is attached, as it often forms part of the capacitance value of the trap.

A further  mechanical consideration in mounting a tribander vertical is with the element to boom brackets.   

The strength of the bracket relies to some extent on even weight distribution downwards on both sides of the element (a little like two people on a see-saw).
  
In the vertical position, the chances of there being uneven wind forces on the element ends is greater, due to the large vertical difference in wind pressure, especially if shielding trees are involved. 

There will be a tendency for the element to twist off vertical, requiring careful pinning of the element and bracket to the boom to prevent this twisting.  

Cheers

Peter   VK3QI