RE: [amsat-bb] Dishnetwork Dish

["Howie DeFelice" <hdefelice@xxxxxxxxxxxxxx>]

The LNB is a combination low noise amplifier and downconverter. The LNA 
amplifies the 12.2 - 12.7 GHz. DBS freqs. The signal then enters a mixer 
where it is mixed with a L.O. of 11,250 MHz. To produce an I.F. of 950 to 
1,450 MHz.  However, large numbers of LNB's were manufactured to 
accommodate the standard domestic Ku band fixed satellite service band of 
11.7 GHz. To 12.2 GHz., using a L.O. of 10,750 MHz., to produce an I.F of 
950 to 1450 MHz. By extending the I.F range to cover a wider band of 950 to 
2050 MHz., manufacturers could use the same L.O. of 10,750 MHz. For both 
the FSS and DBS bands. The L.O. in these devices is the most expensive part 
and are typically stabile to +/- 100 KHz.. The frequency range mentioned is 
the I.F. frequency range. It should also be noted that the DBS service uses 
circular polarization while the FSS service uses orthogonal linear 
polarization. I wonder how hard it would be to get into the LNB's to 
extract and re-tune the L.O.'s ?


Howie
AB2S

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