Re: Request for advice: dish wobbling in the wind, alignment & signal quality

J.W. Davies

Please let us know how you eventually solve your problem.

Your real life experience may be of use to others in a similar situation.



On 06/05/21 08:38, Peter Novak wrote:
Thanks James. Your ideas are also very useful. I found a
mechanical engineer in my close network I will ask him to translate your
and Ernst's ideas into a concrete advice at our site.

I appreciate your help.



On Wed, May 05, 2021 at 09:26:29PM +0100, J.W. Davies wrote:

I agree with Ernst that there is significant wind resonance effects
there. The dish is clearly too flimsy for the windy location.

However, a few things you may wish to try:-

I notice the feed arm has significant movement and this is probably the
source of the biggest impact on signal strength. The position of the LNB
at the focus is very critical.

There is an old trick from the days of Band 1 television where the
hollow aerial elements had a length of rope inserted during manufacture
to dampen wind resonance.
It looks like the LNB feed arm is hollow. So you could try inserting a
piece of rope, tightly fitting in the length of the arm to dampen it.

I agree with the comments of others that the mast is rather weak.
Its not clear how much that is moving from the video but that could also
be packed with pieces of ropes to stiffen and dampen.
If it is blocked at the bottom then even filling it with sand may help.

The flimsy reflector is more problematic. If needed after trying the
above, one possibility is to strengthen the back by applying fibreglass
matting and resin to build up the thickness. The surface being “keyed”
by roughing it with carborundum/ sand  paper first.

The possibility of shielding the back and sides with wooden/plastic
panelling, as a windbreak,  say about 1.5 Metres high, may be another
possibility. The panelling should not be a solid wall as you will get
turbulence downwind, making the situation worse. The panelling should
have gaps in it to make it permeable to the wind, slowing the wind
rather than  stopping it.

Whether its worth the effort is another question and getting a stronger
dish such as the Gibertini OP 125 L may be less hassle.


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