Polarity with C-band

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jluyt

SatelliteGuys Family
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Jan 25, 2008
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Can anyone please explain to me how polarity is controlled on C-band? I know on my KU/DVB system the DICEQ switch controles it, but on c-band?
 
on most DVB systems polarity is controled by voltage through the coax

if your c-band lnbf can accept votage controlled polarity switching then the DVB receiver can do it....... on older c band lnb's ( using a corotor , polorotor ) then polarity switching is controled with the analog receiver using voltage( supplied by three wires) to control a servo on those type of feedhorns

there are only a few DVB receivers that can control the voltage on a corotor / polorotor type feedhorn.
 
The entire site at Geo-Orbit, not just this one page, is a wealth of BUD info.
But I think that link will get you a bit more info on the subject.

I like to tell folks to read the site 'till your eyes bleed, and then you'll know all the fundamentals. - :rolleyes:
 
There are typically 3 types of c-band lnb setup:

1) 1 x C-Band LNB with a polariser - polarity is controlled by a servo motor and the receiver
2) 1 x C-Band LNBf - polarity is controlled by voltage switching, typically 18volts and 13volts
3) 2 x C-Band LNBs on a dual feedhorn - 1 LNB is fixed on Ver the other on Hor - this setup requires either a receiver with dual LNB input or an LNB switch that is controlled in the same was as #2
 
13volts dc on the coax is Vertical
18volts dc on the coax is Horizontal (LNBF)

Normal oldschool feedhorn:
One coax going to an lnb or one c and one Ku lnb with 18-20 volts that never changes.
a small motor called a servo uses three wires from a receiver to physically move a little wire probe in the feedhorn from vertical to Horizontal or any degree in between (skew control).

Red wire +5 volts dc
Black wire Ground
White wire +5 volts dc pulse. (pulsed voltage output from receiver) frequency of voltage pulse determine where the motor moves and how far.
 
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