It makes no sense that the mesh is gone unless your mesh holes have gone larger over the last 13 years . In theory the smaller the hole the better for Ku band( not so much for C band).Originally Posted by Matrix2010
For a mesh dish check with the manufacturer the Ku gain of the dish as the mesh hole should not be larger than a certain diameter( I think its about 1mm , recalling from memory). If the holes are less than this then it makes no difference with a solid one for Ku band .
I prefer smc dish than solid dish. A solid metal dish can warp especially the petalised ones. ( may not be visible) while a smc cannot warp ( It can break off or crack which of cause you can notice).
So still want a solid one?
I have a 2.3 unimesh dish. I was also having trouble aligning it . After investigating it, one the many problems I have is that was a bit of play on the declination stud where the dish rotates.( in service since 1997) ( probably does not matter if it is a small dish) This play is magnified by about 10mm at the edge . So the dish drops down by by around 5mm on way near the west limit and 5mm the other way near the east limit.
So I suspect yours being a 3m dish thing will get worst if your axial is worn
I just cured partly this problem partly yesterday by fitting an axial single direction thrust bearing on the support of the inclination stud. this stud rotates as the dish moves. To be perfect I should be fitting two sets . one on top and the other below the stationary plate . I only fitted the bearing on the top . Fitting the other one below the plate means removing the dish from the H-H mount. This was not done yesterday as it was quite windy and I don't was to take the risk ( as the saying goes the risk out ways the benefits) I will probably fit it during summer 2014.
what a difference it made . I was only getting SNR OF 35 -50% before .Now I am getting around 60 to 85 %. on 30w 13E( 85 % now before 50%)) and 42 E were the best results .The remaining satellite had around 10 to 15 % improvements. 45E is now missing. I should be getting more as I have still not tuned the lnb angle, elevation, declination angles yet.. I am planning to source a cheap satlook micro hd meter to do this.
as others have said rust on the surface does not make any difference unless the mesh holes have become larger which will reduce the Ku gain
Try doing this test
1) Move the dish slowly east limit and then to the west limit and put your ear near as possible to the moving parts of the mount and listen to any unusual noise ( like checking your bearing of the car wheel or your washing machine bearing)
2) ask someone to lift the edges of your dish slightly up and left or right ( Not down as gravity is doing that for you) . you can then check for any play at the moving parts of the mountings. by listening for any suspicious sound and also for play at the edges of the dish
You have a 3meter dish , so a small error in the worn out moving parts can make a very large error at the edges of the dish( in physics this is call the lever principle) . and I strongly suspect this is the case according to the symptoms you have described ie your signals are getting weaker and weaker every day. ( unless the mesh holes are getting bigger and bigger lol ) or perhaps the wind is moving it placing it at a different angle due to the worn rotating axle.
Do you move your dish quite often?
Mind you during the anagoge days some receiver( by using some negative feed back using the maximum signal level and the positioning pulses) can compensate for this but to date no positioner or receiver with deseqc or usual can compensate for this ( not to my knowledge but can anyone please correct if I am wrong)
So the moral of the story is
why change your car if the bearing is gone just get it repaired but if your washing machine bearing is gone then just changed it as is cheaper and better to get a new washing machine .
Don't replace the dish if you are not sure why the symptoms are .Investigate whether the problem can solved repaired or completely replaced economically . Unless you are feedup with the old dish and want a new one ( Like buying new car and have plenty of funding )
In theory its the same principle , only difference is the field of application and economics
You can speak to david of *** , a well known ********** for satellites for he has a degree in electronics engineering. I believe he also owns pr***s*t or has some interest in it . He has helped me a lot in the past over the phone
I hope this helps and is not too technical to you as I am a retired electronic design engineer and do ( still doing) my own car repairs and I also used to work as domestic repair engineer for a short while but not on satellite dishes( except for my own one and friends and family) as I don't fancy drilling holes on the wall on the top of a ladder everyday on unfamiliar properties.
I will post some photos of how I fitted these bearings on my unimesh dish shortly. All components were sourced from Rs Comp*nents.
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