Your
Satellite Downlink
Installing
a New Satellite Dish
IN
THIS SECTION:
Site
Selection
Dish
Selection
LNB
Selection
Dish
and LNB Installation
Setting
and Adjusting the Antenna
Coaxial
Cable
Receivers
LNB
Selection
An
LNB is a combination low-noise amplifier and block down converter. It
converts the feeble 3,700 to 4,200 Mhz satellite signal into a stronger
950 to 1,450 Mhz signal which is easier to send over coaxial cable.
Phased locked loop LNB uses a phased locked loop (PLL) oscillator to
make the LNB's frequency output as stable as it can be made at reasonable
prices. Both Wegener and ABC recommend PLL LNBs for use with their satellite
receivers.
"Digital ready" LNBs are marketed as being "second best" to PLL. Yes,
they are cheaper, but they also have poor stability specifications when
compared to PLL LNBs.
What does "noise temperature" mean anyway? A very simplified explanation
is as follows: Atoms vibrate in any substance that is above absolute
zero in temperature. That means the atoms in the materials in the LNB
amplifiers vibrate. These vibrations create "noise". The signal from
the satellite is so minuscule, you do not want to add a lot of "noise"
to the signal. So you want to find an amplifier with a low "noise temperature".
Typical LNBs are designed for a noise temperature between 20 degrees
Kelvin and 80 degrees Kelvin. If you have an LNB at 120 degrees or 150
degrees, it's worth a few hundred dollars to replace it. Keep the old
one on the shelf as a spare; it's cheap insurance.
