Regarding Dual band LNB operation

[mohanaprakash]

hi

I am having a universal dual band LNB with LO values as 10.6 GHz and 9.75 GHz. I am using sun DTH network. It is having a downlink at 11610 MHz .

If i tune my box to below value it's locking

Downlink 11610
Lo1 9.75
Lo2 0
Xover 0
22KHz OFF

Lband 1860 MHz

If I use my high band then signal is not locking.

ie.
Downlink 11610
Lo1 9.75
Lo2 10.6
Xover 0
22KHz ON

Lband 1010 MHz

Can some one tell whether my understanding on LNB operation is right or not.


regards
Mohanaprakash T

 

[SatelliteAV]

hi

I am having a universal dual band LNB with LO values as 10.6 GHz and 9.75 GHz. I am using sun DTH network. It is having a downlink at 11610 MHz .

If i tune my box to below value it's locking

Downlink 11610
Lo1 9.75
Lo2 0
Xover 0
22KHz OFF

Lband 1860 MHz

If I use my high band then signal is not locking.

ie.
Downlink 11610
Lo1 9.75
Lo2 10.6
Xover 0
22KHz ON

Lband 1010 MHz

Can some one tell whether my understanding on LNB operation is right or not.


regards
Mohanaprakash T

Sir,

11610 reception is tuned using the low LO setting of the dual LO universal LNBF. When setting the 22KHz to ON, the LNBF is using the high LO selection which is unable to tune the 11610 frequency. To tune a frequency in the low LO setting, the 22KHz setting needs to be OFF.

The following setting will work:

Downlink 11610
Lo1 9.75
Lo2 10.6
22KHz AUTO or OFF

 

[mohanaprakash]

Hi thanks for your input


My understanding is LNB will provide the output in the range of 950 MHz to 2150 MHz.

So 11610 - 10600 = 1010 MHz
Similarly 11610 - 97500 = 1860 MHz

Now the L Band frequency is valid in both the cases, so i can select any one LO frequency . If that is the case then it should lock for both case .
Is my understanding is right.

I tested based on your input also, but signal is not locking.

 

[SatelliteAV]

Not familiar with the Sun DTH STB. The Xover setting may trigger the frequency where the receiver switches from the low LO to the high LO. You might ask about this in a Sun DTH forum where members may have better working knowledge of the receiver.

The frequency limitation may be a function of the LNBF design.

 

[mohanaprakash]

Hi i checked in the forum, this is the input i got for L band calulation


Lo1:

X over > downlink or (Lo2 and Xover should 0)

otherwise it will take LO2 for L band calculation.

I my testing is set Xover as zero