Understanding Lnb Frequency and Transponder Frequencies
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| Understanding LNB Frequencies and Transponder Frequencies « on: April 01, 2008, 07:44:50 PM »http://www.galaxy-marketing.com/satellite-support-forum1/index.php?topic=39.0 | |
These are LNB types and frequencies:
DSS Circular LNB = 12.2GHz-12.7GHz
Standard FSS Linear LNB = 11.7GHz-12.2GHz
Universal FSS Linear LNB = 10.7GHz-12.7GHz
Keeping the above frequency range in mind, now let's look at the frequency ranges of your transponder. Keep in mind that the transponder frequencies are presented in MHz.
All DISH Network, DirecTV, and BEV satellites on DSS have transpnder frequencies that don't go below 12200MHz and don't go above 12700MHz.
All Ku band FSS satellites within North America have transponder frequencies ranging…show more content…
As a matter of fact, it is entirely possible to become severely shocked in discovering 50 Hz or 60 Hz AC Mains currents on the outer conductors. Be extremely cautious.
The quality and smoothing of the DC supplies used for the LNBs are also of great importance.
Testing an LNB * Check the ammeter drawing the DC current from the power supply (approx. number of mA’s provided by the manufacturer). * Poor quality (or corroded) F type connections are the most typical cause of concern. * The center pin (of the F connector plug) should stick out ~ 2mm, away from the surrounding ring. * A satellite finder power meter is also helpful. By pointing the LNB up at outer space (clear sky), the noise temperature contribution from the surroundings becomes negligible.
The meter reading will directly correspond to the LNB’s noise temperature.
If, for example, pointing the meter to outer space reads 100K (K is short for Kelvin, which measures absolute temperature), then the user points the LNB towards the ground (say at a temperature of approximately 300K), the noise power meter reading should go up accordingly, to roughly 400K (100K +300K).
LNBs that fail on a particular polarization (or particular frequency band) may only do so at certain temperatures.
If attempting to replace an LNB in a VSAT system, be sure to check both the supply voltage and the transmit reject filter as continuously blowing up LNBs can get cost prohibitive quite rapidly.