Circular Ku Channels

**SatelliteAV** · 08-25-2012 08:51 AM

Direct connect to the "C" output of the LNBF. Set the STB LO to 11250. Blindscan 82w, 91w,110w, 119w, etc. You will find circular transponders with frequencies between 12200 and 12750mhz.

The QPH-031 LNBFs have very tight frequency drop off on the Circular and Linear outputs. Since these outputs are hardwired to the respective polarity circuits, there will be very little portion of the other frequency range that could be logged. You might scan a few frequencies below 12200 on the "C" output and a few frequencies above 12200 on the "L" output. The reception of linear with the circular circuits and circular with the linear circuits is possible, but the signals are attenuated by approximately 3dB (each 3dB is a doubling of power). You will see some transponders from the opposite polarity, but they will be much weaker!

**Magic Static** · 08-25-2012 09:18 AM

One other important note. Most of the transponders on the DSS sats use a modulation your receiver can't do, 8PSK with Turbo FEC, most commonly refered to as Turbo 8PSK. Rarely, hidden channels will show in the clear for a short time, but for the most part there is nothing there to watch.
Iceberg provided the coordinates for Channel 101 on Dish119. That is like the only ITC channel to use for testing the LNBF.

**farwest5050** · 08-26-2012 02:25 PM

Hey MagicStatic,hope you be fine there.Question: When we remove the dielectric plate from a 621 lnbf we are looking for linear polarity.So we are not able to lock circular polarity.Does that work on C band only or does it affect KU band also?

**SatelliteAV** · 08-26-2012 03:53 PM

The dielectric plate in the C/KU is only for C-band. C/KU LNBFs do not receive circular KU-band( with or without the dielectric slab).

**phlatwound** · 08-26-2012 04:46 PM

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Originally Posted by SatelliteAV

The dielectric plate in the C/KU is only for C-band. C/KU LNBFs do not receive circular KU-band( with or without the dielectric slab).

Why is that? Never gave it much thought but I had (incorrectly) assumed the slab would convert the feed to circular reception in both bands.

**SatelliteAV** · 08-26-2012 05:15 PM

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Originally Posted by phlatwound

Why is that? Never gave it much thought but I had (incorrectly) assumed the slab would convert the feed to circular reception in both bands.

Just the design and placement of the dielectric slab in the feedhorn and the position of the KU probes within the cavity.

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