i have experimented with the various lnb settings for sometime and am yet to see a notable difference---5150,5750(cBaNd),9750,10600,10750,11300,11475(KU). can someone pls explain in plain language how tweaking these settings affects sat signals?under what conditions is tweaking helpful,considering that the receivers come with preset parameters for the various sat positions?the only thing i know is that they are megahertz frequencies. Am always amused that am labelled 'expert'by the forum software and yet i know so little.
Alright.
If you've ever checked your lnb branding c or ku, within the specifications, they give an "L.O" frequency or Local Oscillator frequency. A local oscillator is a module within the lnb that oscillates or vibrates (electrically) at a predetermined frequency to select a band of incoming frequencies from the satellite using resonance.
Simply put, if it vibrates at say 10 hertz or 10 cycles per second, it will resonate with or match with and therefore tune to frequncies say 12 to 16 hertz from the satellite.
The reason for this is satellites broadcast at a wide band or wide range of frequencies typically 10 to 12.5Mhz for ku and 3 to 5Mhz for C. It happens that it used to be difficult to create a single oscillator within an lnb that can tune to full range e of these frequencies. Therefore 2 or 3 or even 4 local oscillators were built in to tune to various sections of the frequency spectrum. Modern lnbs however have "universal" oscillators that can tune to atleast most of the satellite frequency spectrum especially ku frequencies.
Specific band local oscillators have their specific frequencies say 10600 khz which will tune to 10 to 11Mhz signals from the satellite another 10750 khz which will tune to 11.1 to 12.50Mhz signals from the sat (for ku). Such that if you want to watch a channel on freq 10950 H 27500, the reciever will activate one LO for the lower band of frequencies and then when you switch to a channel on 12226 H 27500, another LO will be used for the higher band of frequencies.
If you select 10600/10750 or "universal" on the lnb settings this transition from low to high band will be smooth because the receiver will switch LOs automatically using the 22khz tone signal which you should also put on or auto to signal the lnb to shift LOs. However when you select 10600 only youll have problem switching to higher band of frequencies say 12226.
It's like driving an automatic car on gear L. It will never shift to high gear even when its required.
Therefore When you're changing "lnb frequency" at the settings, its Local oscillator frequency that you're changing which will in turn select the high or low band frequencies from the satellite as required.
Playing with these LNB frequency settings hardly ever improve reception. It's always either you get something or not.
If you're not sure just select universal for the full band of freqs.
However some lnbs which am sure are not available locally operate with a single specific LO frequency branded on it and you must select that particular LO frequency at the settings for it to work. That's why you have many useless options at the lnb freq settings. The manufacturer is trying to accommodate all these wayward technical lnbs.