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dish size, quality and fine pointing tip

Markus Kempf
 

I recently rebuild my satellite reception setup. I used two dishes, a 100cm Gibertini XP for the reception of Astra 19E, Hotbird 13E and Astra 28E and a Triax 78cm for Eutelsat10A with an Inverto Black Ultra LNB. My best CNR for Eumetcast was 10.6. 12y ago, no 3deg distance capable LNB holders and LNBs were available, the main reason for the two dish setup. After 12y of use, the LNBs were ready for preventive maintenance :-) I bought small new ones together with the new 3deg holders (also capable of height adjustement). Even after careful pointing of the dish to the 10E position in the center, I had disastrous results. The CNR was down to 7.6. By chance, I discovered that slight pushing of the upper rim of the dish improved the reception a lot, CNR went up to 9.6. Still a lot below the value of the smaller dish. The conclusion after a lot of further testing is that the figure quality of the 1m Gibertini dish is really bad.
I have bought a replacement dish, a 100cm Gibertini SE Profi and will, weather permitting, replace the old unit.

Fine Pointing tip: The geostationary sats have telemetry beacons that can be received/used with a simple RTL-SDR dongle connected to the LNB (I used the loop through port of my TBS 5925). For Eutelsat10E, the beacons are at 3626,00 R / 10950,20 H / 11699,80 H / 12501,00 H / 12501,50 V. For Eumetcast the beacon in the right band/pol is at 10950,20 H. You have to dial to 1200.2 Mhz because of the 9750 Mhz LOF. After pickup of the signal you can easily optimize for best reception.

Markus