East Part of Ku Arc Knocked Out By Wind Storm

[unclefrank]

We had violent wind storms for the past couple of days. I have a 9' solid dish equipped for C and Ku bands. Now that the wind has slowed down I have lost signal on all of the Ku satellites east of AMC 3. What ever got misaligned on the dish should be a simple adjustment. Everything from AMC 3 west is perfect. Can anyone refresh my memory on what possibly has to be adjusted on the dish? We also have some heavy cloud cover today, can this affect Ku band signals?

[jvvh5897]

Yes, clouds with liquid water absorb and scatter the 12 GHz frequencies a lot! C band not so much. Since you have part of the arc OK, I'm thinking that the clouds are the trouble and not the allignment.

[Terryl]

Your dish uses what is called a polar mount, this means it is the mount for your dish is aligned to the North geographic pole, if the wind twisted your dish mount a bit to the west you may be only able to track that part of the arc.

One other possibility is the mounting pole it's self has been twisted or bent off plumb, check this with a level, it should be absolutely vertical front to back left to right and all the way around.

I have also see the concrete base lean to one side due to the ground being saturated with too much water, (base was not deep enough) this can through all sorts of things out of kilter.

[unclefrank]

Thank you Terryl, the polar mount was recently adjusted and I did not over tighten the bolts. That is likely the answer. I forgot all the little nuances about Ku as I did not have it on my dish for many years and just added a new Corotor. I just guessed at the f/d so the feed is likely not optimized. How important is getting the f/d exactly right? Also as jvvh mentioned there is a lot of cloud cover and rain today so I will do the adjustment when the sun comes back out.

I just edited this post after I adjusted the polar mount. I turned it about 1/64 of an inch to the west and Amc 6 and Amc 9 popped right in. Your help is greatly appreciated!

[Terryl]

Wind can do all sorts of things to a 9 foot solid dish, if the wind is too much something may give if the bolts are not tight enough, I don't remember if there are any torque spec's for the mount but someone who has a dish like yours may have a spec for this.

[Terryl]

Another thing to do is to make a permanent mark from the mount to the pipe, this will tell you if something has moved.

[unclefrank]

Another thing to do is to make a permanent mark from the mount to the pipe, this will tell you if something has moved.
yes, I've had that mark on the pipe for many years and the massive force of the wind definitely moved the dish on the mount a substantial amount.