lnb switching frequency

dazzaessexuk

new here and to satellite could anyone explain how you alter the channel frequencies that appear in what satellite magazine so my meter will understand them i know you have to subtract 9.750 and i think 10.600 from them but can anyone point me in the direction of the information of why we do this and for what lnbs is it deduct 10.600 for vh and hh and 9.750 for vl and hl and what the cut off is for low and high band , please help me get my head around this many thanks

Analoguesat

Cut off / switch point is normally around 11700khz.

Ive changed your thread title to something meaningful. "Hi all" isnt much use to anyone.

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Topper

Welcome to the forum gazzaessexuk

What exactly is it you are trying to do, most lnb's are universal so you do not need to get involved in quattros. Please explain what you are doing or trying to

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Robbo

Well,

The signal frequencies transmitted in ku Band from the satellites range from 10.7 GHz to 12.75GHz.

However to get this bandwidth down the cable it is split into two bands:- Low band-10.7 GHz to 11.8 GHz and High band 11.6 GHz to 12.75 GHz.

The band selection is performed within the Universal LNB using a mixer and a local oscillator.

The LNB contains two local oscillators:- one at 9.75 GHz and the other at 10.6 GHz.

The purpose of the mixer and LO is to downconvert the signal that the dish gets (10.7 GHz to 12.75 GHz) to a much lower frequency, that will not suffer such severe attenuation in the cable as the higher frequencies.

For example

10.7 GHz to 11.8 GHz ->> 950 MHz to 2.05 GHz
11.6 Ghz to 12.7 GHz ->> 1 GHz to 2.15 GHz

The switching point is around 11.7 GHz

The switching is normally initiated by the receiver by sending a 22kHz tone to the LNB, with no tone it is low band, with the tone it is high band.

Robbo

rolfw

Which meter are you using dazza, they normally have a setting for LNB type in the setup menu.

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dazzaessexuk

its a promax prolink 4c and trying to set it up to work out multi-switches its just that the magazine frequencies do not give the actual frequency that would show on the meter if i was checking the vh vl and hh and hl used to using horizon meter but this meter is much more complicated. i think it over complicates the issue but its what i got to use .many thanks so far guys

rolfw

If you go into the setup menu, you can set the LNB type by typing in the local oscillator 9750.0 for low band and 10600.0 for high band, then the meter will show the correct frequencies.

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dazzaessexuk

top man thanks buddy will save me a lot of time

dazzaessexuk

sorry i was wrong its a prolink3+ meter the local lnb osc is set at 10600.0 but it has clarified what i need to ask and thats how i get from say 12.207ghz v for sky news in the magazine to a mhz frequency (ie what would be the frequency on the meter for checking, do i deduct 10600,giving 1607 mhz on the meter and if this is correct ,am i also correct in assuming that andy frequency below 11.700 ghz in the magazine would be deamed a low channel and anything above this is a high channel.

rolfw

Just checking through the manual http://home.promax.es/ftp/Acrobats/E.../PROLINK-3.pdf you should be able to set a high and low band local oscillator, there should be no working out required.

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satelliteman

10.7ghz - 11.7 ghz = low band = 9.75 Lo = no tone
11.75ghz - 12.75ghz = high band = 10.600 Lo = 22khz tone.

If you have prolink 3+ you must be in the trade. if you are in the trade, you should already know these basics, especially if you are involved with IRS.

I have a prolink 4 c and you can change the setting to 13v no tone, 13 v tone, 18 v no tone and 18v tone.

dazzaessexuk

thanks satelliteman for your reply yes it is irs and yes i am in the trade but have never fitted these sytems i am used to sky digital and sky digital plus but mainly worked on aerial systems as previous employers tryed not to get involved in satellite work unless it was for repairs only.
i have only been swapping out stuff that was us and the meter i used before , was an horizon and took all the calculations out of the equation , i now feel i need to know the whys and therefores, so was purely asking on a learning basis , and yes your right i should know the answers to these questions , thats why i was asking.
the question was aimed at this specific meters settings

satelliteman

You can't go wrong with the prolink meters really, they are very pleasing to work with; though I now have a Rover St-4 as an upgrade.

With practice and the ability to read the frequency and trace on spec mode you will be able to identify which cables from a quattro are for which band without tracing them back.

paul

dazzaessexuk

this is only a temp situation new tv explorer meters are on the way which should make life easier but feel i still need to know the answers to the questions i asked, as i said all i needed to know before was which group of channels were missing and i could find the problem and swap out the offending item , but now i am getting to the stage where i need to be involved with the build and design process i really need to know these things and any help is appreciated .