Lnb

[ishtiaq_sb]

Re: Lnb

if u r dish is fix then lnb then the signals quality will varies from satellite to satellite and if u r system is motorized then there is no a little difference for the signals qualityand in a fix dish u need to tune u r lnb every time when u change the from satellite to satellite

[kalpikos]

Re: Lnb

Changing your cable and using a new one without any cutting is a very good idea, and I'm sure that you will see a significant improvement on your signal, but may be can't this fix your problem.
Just buy a new lnb with better quality and try it.

[ishtiaq_sb]

Re: Lnb

the dish experts also suggest that the length of the wire may also not more than 15 to 20 meters it also effects the signals quality

[nanor01]

Re: Lnb

Its a motorised 1.2 offset dish with quad lnb

[aplok]

Re: Lnb

so if I completely replace the cable this should fix the problem altogether?

hi,

well, all this depends of your installation

and the coax cable, connector quality you have

to give you an example, you have these signal loss for each 100m of coax sat cable reduce the signal
from 23.3 26.9 26.9 44.6 according to the quality of the cable

figures to calculate signal loss for UHF (Freeview) and LNB (satellite)
__http://www.satcure.co.uk/tech/cablespecs.htm

... and you have a large coax cable choice:
__http://www.satcure.co.uk/accs/page8.htm

for exemple,
- if the cable length is the main issue, try cable quality first with a one-piece cable (without intermediate connection loss) before buying it ...

- if the lnb is poor snr, try a better one

- if the footprint is poor, try a larger dish ( __http://www.satbeams.com/footprints )

- if junctions and connector are poor, try with better one

- if the channel is noisy, try a stronger transponder

... and compare your's with an operational local sat installation

[Mobley3]

Re: Lnb

Its a motorised 1.2 offset dish with quad lnb

You can NOT use a Sly Lnb on this system, the reason you are getting poor results is because the dish is not illuminating the Lnb correctly. The Feedhorn on a Sly Lnb is completely different. A Sly lnb is shaped to focus on a dish that is elliptical from edge to edge your 1.2 Mtr dish is elliptical from top to bottom. You need to buy the correct Lnb for this. An Inverto Black Ultra would be my suggestion ,not that expensive and you should see a significant improvement. All of the suggestions re tuning it will still apply.

Regards Mobley3

[benchsirius]

Re: Lnb

Hi , I think the fact that the signal varies a lot indicates 3 possibilities
1) The lnb is loose in the bracket and is slipping.
2) Most likely the connector at the end of the cable became loose when you unscrewed it. If you can completely disconnect the end of the cable and check that the braid is in contact with the outside of the connector and that NO BRAID is impacting on the inner copper core. It is also possible that you need more or less of the inner connector as maybe it was a little short and is wobbling in and out of the the lnb
3) You may have moved your dish a little when you changed the lnb.
If it is none of these and your OLD lnb still works , send it back.
What noise ratio do the old and new lnb have.

[aplok]

Re: Lnb

...The Feedhorn on a Sly Lnb is completely different. A Sly lnb is shaped to focus on a dish that is elliptical from edge to edge your 1.2 Mtr dish is elliptical from top to bottom...

and what about the idea to mount the lnb with a 90° rotation,
( to best suit elliptical from edge to edge vs is elliptical from top to bottom )
and rescan the sat's
to adjust the polarisation ?

at least for a test ?

[Mobley3]

Re: Lnb

and what about the idea to mount the lnb with a 90° rotation,
( to best suit elliptical from edge to edge vs is elliptical from top to bottom )
and rescan the sat's
to adjust the polarisation ?

at least for a test ?

Personally I would not waste my time, the polarization for Vertical and Horizontal channels is selected by the voltage ie 13V - 18V when the Lnb is vertical. On a fixed dish you normally skew the Lnb in the mount to get the best compromise, you do not do this with motorized dishes as the motor takes care of this as it turns, if you rotate the lnb by this amount I am not sure what kind of result you might get. The point is that at the end of the day you will still not have a properly working system. If it were my system I would be looking at a C120 Lnb with separate Co-Rotor, but that is a completely different scenario.

Regards Mobley3

[kontoni]

Re: Lnb

On a fixed dish you normally skew the Lnb in the mount to get the best compromise, you do not do this with motorized dishes as the motor takes care of this as it turns, if you rotate the lnb by this amount I am not sure what kind of result you might get.

well this sounds strange to me.

i have an offset motorized dish 85 cm moving on two axis hor+ ver with old omniview motor .

and it makes huge difference lnb skew for example when i want to see turksat it's completely different skew angle than hispasat.

[Mobley3]

Re: Lnb

Not sure I fully understand, Are you using a system with 2 Motors to track inclined orbit satellites?. Normally with a standard motorized set-up you do not skew the Lnb, there may be some situations when a slight adjustment will gain you a little extra but I think we are moving off topic here as I believe nanor01's problem relates to something completely different.

Regards Mobley3

[kontoni]

Re: Lnb

dear mobley3
yes i agree nanor01's problem is different i think.

but just to answer your query and stop it there no it is one motor with positioner like box and moves dish to predefined sat position in two steps first horizontally and then elevation.

[turminator]

Re: Lnb

i think lnb power is most important matter

[sideralgr]

Re: Lnb

hi I changed my LNB and find that certain frequencies on some satellites variate a lot from full signal to none at all and signal continually fluctuates and yet if I put original lnb back on dish this doesn't happen
Can anyone help or has anyone any ideas?

also the noise factor is important for a lnb

[herrr]

Re: Lnb

i think lnb power is most important matter

Power?
What power?
Please, don't say absurd things...