efficiency of universal lnb´s at large angles

[kenhib]

I have a motorised system in the South of Spain and I am getting much weaker signals on 28E than on a dish fixed on 28E (both dishes are 1.3m). I am enquiring about resetting the motorised system but an installer has suggested that this may not have much effect, as the efficiency of the polarisation of a universal lnb falls off as you move away from 0 degrees and gets much worse after 19 degrees.
I realise the universal lnb will not be as efficient as the old separate polarisation controls I first used on my echostar 8700, but is it really that bad?
Thanks for any advice!

[ouagadougou]

It sounds like bad advice to me.

As long as the dish mount/motor is a horizon to horizon or polar type then the skew angle for polarisation is adjusted by the motor/mount movement assuming the motor is installed correctly.

You say the dishes are of the same type but dont say if they are offset of prime focus ?? and what type of LNB are using on each dish.

Cheers.

[kenhib]

Thanks for your reply. The dishes are both offset. The motorised has a twin output lnb. I don´t know what type - the fixed is a 0.5db Televes -the motorised is on the roof so I can´t get at it but is probably a Televes.(I have tried a 0.3lnb on the fixed dish but it gives inferior results - that is a whole new subject, discussed in the old forum!)
I doubted the advice given, as if correct no one with a motorised system would receive the channels on the wider satellites.

[spirochete]

Hi m8,

I think the comments about the LNB are wrong provided the motor /mount are tracking properly.

As said above, if you are using a horizon to horizon mount the dish skew should be adjusted automatically and keep the LNB's relative position correct.

There are a number of alignment errors that can cause this sort of problem though.......

I have scanned a couple of pages from my Jaeger manual which shows how this SHOULD be set up in principle and where the errors can occur with tracking and why.

Can't seem to add attachments to a PM on this forum so if you PM me your e-mail address and send the scanned pages to you directly.

??

Spiro'

[Bradwall]

The best advice I can give you is to find another, competent, installer. The one you have spoken to is talking rubbish m8.

[kenhib]

Good advice, however they are not easy to find in Spain. My own theory (unfortunately!) is there was a lack of communication between the original installer and the builder who put the concrete mounting block on the roof, and the pole is not absolutely vertical.
I hope I´m wrong but it makes more sense than the other theory!!
Thanks to all those who have tried to help!

[Bradwall]

Is there any possibility of moving your motorised dish to where you can get at it , say on a flat roof or in the garden, and still cover the arc you require? My own dish was on a 1.5 metre pole in our garden and was a doddle to work on. Keep in mind that the dish needs to be approx 2X the height of an abstruction away from the obstruction to be able to look over it at satellites ( so 4m away from a 2m high wall )

[Prontopro]

If the pole is not absolutely vertical then your theory is correct you will see a drop off at wide angles as the skew error of the LNB increases. The only way to check is to get on a ladder and measure it.

Have you also ruled out the possibility of a faulty or failing LNB?
Have you had good signals before and this is just happening now or has it always been like this?