new to LNB 's

[regisma]

Hi,

After making a channel list with the SatCoDX program for my area, I have just figured out the following:

In order to see all the Free To Air Satellite even if I have a motor I need four LNB: Right Hand, Left Hand, Vertical LNB and Horizontal LNB.

What does mean a DSS LNB?

Doest the Right Hand hand LNB catch circular waves and the V and H one catch the serial one?

Do I need to pay $$ for dual LNB?

Are they hard to find and can I have an idea of the price to pay ?

thanks

Reg

[bobkat]

LNBs are classified as either "circular" or "linear" polarity. DSS LNBs are used for satellites like DirecTv, Dishnetwork and Bell ExpressVu; whereas linear LNBs are used for satellites like T5, G10, AMC4 and others.

A "circular" LNB (like DSS) uses left and right hand polarities while a "linear" LNB uses vertical and horizontal; you don't need four LNBs since a "circular" LNB handles both left and right; likewise, a "linear" LNB handles both vertical and horizontal.

A dual output LNB simply allows you to run two (or more with a multiswitch) receivers from it.

The type of LNB you need depends on what satellites you want to pull in.

kat

[deenie]

WRT linear (V/H) LNB's, are they the ones that require a skew adjustment?

A dual output LNB, because it has two outputs, can handle two or more receivers because one LNB output is assigned vertical (or Left Hand) and
the other output is assigned horizontal (or Right Hand) polarized signals. Is that correct?

My buddy has a DishPro antenna with two dual LNBs (middle slot empty) that has a tilt adjustment. What are tilt and skew? How do they differ?

[bobkat]

Originally Posted by deenie

WRT linear (V/H) LNB's, are they the ones that require a skew adjustment?

A dual output LNB, because it has two outputs, can handle two or more receivers because one LNB output is assigned vertical (or Left Hand) and
the other output is assigned horizontal (or Right Hand) polarized signals. Is that correct?

My buddy has a DishPro antenna with two dual LNBs (middle slot empty) that has a tilt adjustment. What are tilt and skew? How do they differ?

Yes, linear LNBs require a skew adjustment.

A dual output LNB is simply two independent LNBs sharing one feedhorn. Each output handles both polarities when used with two receivers. When a dual output LNB is connected to a multiswitch then the multiswitch locks one side (output) of the LNB on one polarity and the other side on the other polarity, as you say.

The tilt or skew (same thing) of the DishPro dish is to allow one dish to receive signals from two or more satellites at the same time.

kat

[deenie]

Kat, thank you for the previous info.

WRT a 2 LNB sat antenna, is it possible to take the individuals skew angles for the LNBs, then use the average of the two skews to come up with a tilt angle for the dish?

Is a 90 deg dish tilt considered neutral or no tilt?

Peace, deenie

[bobkat]

Originally Posted by deenie

Kat, thank you for the previous info.

WRT a 2 LNB sat antenna, is it possible to take the individuals skew angles for the LNBs, then use the average of the two skews to come up with a tilt angle for the dish?

Is a 90 deg dish tilt considered neutral or no tilt?

Peace, deenie

OK, for the Dish 500 you don't need to concern yourself with LNB skew; there isn't any. You should refer to the Dishnetwork skew settings for your area and preset the dish skew at that. A 90 degree dish skew is considered neutral, yes.

kat

[deenie]

Kat,

Two questions:

1) Why does a Dish 500 antenna require a tilt since the individual LNBs are
circular polarized as are the respective satellites? A single LNB antenna with a circular LNB requires no tilt. So why does a dual circular LNB antenna like the Dish 500 need a tilt adjustment? This seems to indicate that LNB skew and dish tilt are not quite the same thing.

2) For the general case where one has a generic two LNB antenna, is it possible to calculate the correct tilt of the dish by averaging the required skew of the individual LNBs and then using the result to tilt the dish from the 90 deg postion?

Thanks, deenie

[bobkat]

With the Dish500 antenna, or any other antenna with more than one LNB, the tilt is for the dish, not the LNBs. What the Dish500 is doing is pointing at 2 satellites at the same time and so the "tilt" of the dish is to find the elevation midpoint since the two satellites will have differing elevations. For example, Echostar 7 at 119 degrees has an elevation of 26 for my area and Echostar 8.6 at 110 degrees has an elevation of 30. So, by tilting the whole dish assembly you are essentially finding a compromise between these two elevations so the dish can "see" both of them at the same time. Don't confuse this type of "tilt" with LNB tilt or "skew" as they are different things. Circular LNBs do not need a tilt adjustment; this is why the single LNB Dishnetwork dishes are always mounted straight across the horizontal, as you pointed out.

kat

[videobruce]

To use one dish for FTA and CA I would need both types of LNB?'s

What are the temp. ranges of todays KU LNB's?

[bobkat]

Originally Posted by videobruce

To use one dish for FTA and CA I would need both types of LNB?'s

What are the temp. ranges of todays KU LNB's?

The LNB type depends on what satellite you want to point your dish at; whether the channels are FTA or conditional access has no bearing on the LNB type.

Temperature ranges (I assume you are talking degrees Kelvin) are not usually listed on KU band LNBs, at least none that I have seen.

kat

[videobruce]

I have seen listings for .3 and .6 degree so far and I haven't really looked for any.
The last LNA (yes, LNA) I looked at was 120 degrees (no decimal ponit).

[lpgao939]

So the circular does not need skew adjustment?

[bobkat]

Originally Posted by lpgao939

So the circular does not need skew adjustment?

Correct. Not for the LNB itself.

kat