Newbie Problem with Motor Positioning

Shaun

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#1
I've just had a new motorised dish (80 cm) and receiver (GbSat) installed to replace my old analogue receiver. I noticed however that on Hispasat, Antena 3 started to break up and get steadily worse over a period of a couple of weeks. Eventually I lost Antena 3 all together along with several other channels on Hispasat. Shortly after this I noticed that if the dish was moving from west to east, then it was unable to lock onto Hotbird and pick up any of its channels, however if the dish was moving from east to west then it was able to lock onto Hotbird fine.

Before contacting the satellite dealer who installed and fitted my system I decided to check out a few of the options on the receiver and I found that I could fine tune the motor positioning for each of the satellites and that by optimising the signal strength/quality I could recover all the channels. Unfortunately the following day I noticed that Antena 3 was starting to break up a little again, so I re-checked the motor positioning and found that Hispasat and Hotbird were a little out (I didn't check any of the others). I fine tuned them again and all seems to have worked OK for the last few days.

Is this sort of thing normal for motorised dishes and will I have to regularly fine tune the motor positioning for ever more? Or does my system have a problem? If so, does anyone know what the problem might be? After I reset the positioning on the dish for the first time, I contacted my satellite dealer and he told me that I might need to fine tune Hispasat occasionally as its not a particularly strong satellite.

Many thanks in advance for any suggestions.
 

Channel Hopper

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#2
Ive found that the GBSat does have trouble in setting the correct positions, and then returning to them after a time

This may only be on certain motors (I have not tried them all)

As you have managed to recover the channels once they have gone off, you have confirmed its nothing to do with outside (Movement or play in the motor mount)

Ask your installer to bring another brand of DiSEqC receiver with him when he comes over to check, and run this up for an hour or so
 

Shaun

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#3
Thanks Channel Hopper, I don't know what motor I have, I only know it's a DiSEqC 1.2 (whatever that means). Also, I'm not sure I understand why being able to recover the channels implies there's no movement or play in the motor mount. Couldn't it be that the fine tuning of the motor positioning simply counter acts movements in the dish caused for example by the wind? One thing that concerns me is that the dish is mounted on a pole and points out over the roof (see photo below).



I know the dish is only 80 cm, but I was wondering how effected it might be by the wind. Today was quite breezy and I noticed that Antena 3 was pretty broken up for a while, but then it seemed to sort itself out again (no re-alignment required). I don't know if its normal for Hispasat channels to suffer intermittently like this. Also, when my system was installed, the cable from my old analogue system was re-used. This is about 5 years old and I was wondering whether this might be causing a problem. Finally, I normally switch off the receiver at the mains when I'm not using it, is it better to leave it in standby mode? Maybe this generates spikes or something which might offset the motor. Many thanks in advance for any insight into these little problems.
 

lee32uk

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#4
I have a motorised system and i find that Hispasat gives as strong a signal as Astra or Hotbird on most channels.The palco 'L' polorised ones are weaker.Most other channels are about 75%+ on 1.1m dish in manchester.

Lee
 

2old4this

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#5
Shaun-
once the dish positions are programmed into the receiver/positioner, they are fixed (at least, until you next explicitly re-program them). They do not automatically fine-tune to compensate for wind or anything else.

The reason that the dish can blow off course and then return to its original position is that the dish mount/motor itself is not moving. IE, the mount stays fixed exactly where it was on the wall, and the motor (unless worn) will keep the dish fixed at its current position. The wind only bends the dish/pole - and when the wind drops again, it springs back to its actual original position. The amount of movement needed to lose the signal is miniscule.

I can't imagine that switching the receiver off will upset the positioning. True, noise spikes in the cable can spurious motor pulses but I've only heard of that happening in badly insulated non-DiSEqC motors cables and never as a result of switching on/off.

5-yr old cable shouldn't be a problem so long as it was properly insulated (undamaged, with water-proofing at the LNB connection) and as long as it was proper sat-cable in the first place (so not the lower quality coax typically used for in-house TV signal distribution).

2old
 

Channel Hopper

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#6
Looking at the picture I can see where the problems lie in the hardware

You have an aluminium pole (not good as it will bend in the wind)
You have an aerial standard T + K (not good as they are not sturdy enough)
You have a DiSEqC motor with a very soft steel bracket (that will bend in hight winds)
You have a Triax Dish (which has a tendency to oscillate in high winds)
You really need to change everything outside to ensure it stands up to the winds coming over the house

Then start looking at the receiver, which does have a tendency to give problems with the motor you have fitted, Ive tried them together twice and couldnt get them to talk with any degree of reliability
 

Shaun

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#7
Oh dear ....
This was installed by a local specialist. I presume there are normal installation practices for motorised dishes on poles. Does this not conform to normal recognised practices?
 

rolfw

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Berkshire
#8
Yes, agreed that its not ideal, one major improvement could be made by changing the pole for a steel/scaffolding pole and adding a third bracket between the other two. The thin motor bracket should probably bear up under normal conditions, but the aluminium pole is not really designed to withstand the amount of force the 80cm dish will generate under windy conditions.
 

Channel Hopper

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#9
It would be OK in the garden but not on a roof

The equipment as shown would not normally cost anyone in the trade more than about £120 and anyone with a ladder could probably set it up in just over two hours

You really do need something more substantial

Call the engineer back to change the pole first, and make sure he gives you a written guarantee which includes workmanship, I have a feeling he will have to return over the winter period to upgrade the rest (aluminium fractures in cold weather when it is bent back and forwards)
 

Shaun

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#10
Many thanks for your feedback. In case anyone is interested, my dish seems to have survived the recent storms with no re-alignment needed (so far). The reception was effected during the strong winds, although not as much as I had expected. The reception of Antena 3 seems more effected by heavy (storm) clouds than wind. For good weather and normal cloud conditions I get a good signal, but for heavy cloud conditions, Antena 3 becomes a bit intermittent. Is an 80cm dish sufficient for Hispasat reception in Hampshire? or could I expect to get significantly better reception during heavy cloud with a 1M dish? Once again, many thanks for the feedback.
 

rolfw

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Berkshire
#11
Well I'm using a 63cm Zone II minidish in Berkshire Shaun (not too far away from Do'nut city :) ) and in all but really rainy weather I pull in Hispasat, so your 80cm should be OK in most circumstances.
 

Channel Hopper

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#12
Im surprised it survived intact

Anyhow increasing to a 1m dish will give the wind an extra 35% area of equipment to blow against
 
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