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Sky Digital BSkyB, Freesat & Saorsat support forum
Sky & Freesat fringe reception
A 3.7m Prodeline dish for Astra 2D
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<blockquote data-quote="pjgregory" data-source="post: 558256" data-attributes="member: 288654"><p>On Thursady, I finished the stand that allows me to work inside the dish. It is made of 30mm steel L section angle, with the base and supports bolted down to the concrete pad. Two wooden boards on top allowed me to keel or stand inside the dish to attach the feed mounting arms. (042.jpg and 043.jpg)</p><p></p><p>With no respose to my earlier question about the correct position to use for focal distance measurement, I opted for the front of the throat, cutting a length of plastic conduit to the 1372mm (54") specified by Prodeline. I used this a guage to adjust the distance of the feed horn from the dish. (044.jpg)</p><p></p><p>Then with the laser inserted in the feed horn tube I checked the aligment of the feed horn axis with the center of the dish, rotating the laser by hand in the tube to trace out circles on the base plate. This proved more difficult than I had imaginged as there was some "play" in the machined mount. Tightening the two grub screws could alter the spot position on the base plate by 1-2 cm. </p><p></p><p>I then found it impossible to fix the LNB onto the fixed feed horn as I coiuld not get the screws in place. In the end, I put a layer of clear tape aroung the feed horn tube to make it a tight fit in the mount before uncrewed the scaler ring, attaching the LNB nad then putting it all back together again. Not perfect, but I am fairy sure that I aligned the axis to within 1cm of the center.</p><p></p><p>Finally the moment of truth. </p><p></p><p>I connected my Satlook spectrum analyser to the LNB, set the elevation to 37.5 degrees and rotated the dish in azimuth to lock onto a strong low band Astra 2 transponder - 10964H. After a few minutes of trying with the wrong satellite (Arabsat at 30.5 degrees east), I got a lock on Astra 2D and peaked the signal in both elevation and azimuth. Then set the LNB tilt to 9 degrees.</p><p></p><p>Back in the house, connected to the Pace Skybox, I had Radio 4 on 11954H, but NO BBC1,2 or ITV!</p><p></p><p>Disaster - after all this work and care what a let down. My wife went very quite.</p><p></p><p>So there must be something wrong. I checked the signal strength on 10964H and found that I was getting 71.2db on the meter. I removed the LNB, put it back on the 1.2m Channel master dish and measured 75.8db. </p><p></p><p>That was enougth for the day. Corviello, who has posed about his own experiences with a 3.4m Prodeline disk is visiting on Friday, so I will try again then.</p><p></p><p>PJG</p></blockquote><p></p>
[QUOTE="pjgregory, post: 558256, member: 288654"] On Thursady, I finished the stand that allows me to work inside the dish. It is made of 30mm steel L section angle, with the base and supports bolted down to the concrete pad. Two wooden boards on top allowed me to keel or stand inside the dish to attach the feed mounting arms. (042.jpg and 043.jpg) With no respose to my earlier question about the correct position to use for focal distance measurement, I opted for the front of the throat, cutting a length of plastic conduit to the 1372mm (54") specified by Prodeline. I used this a guage to adjust the distance of the feed horn from the dish. (044.jpg) Then with the laser inserted in the feed horn tube I checked the aligment of the feed horn axis with the center of the dish, rotating the laser by hand in the tube to trace out circles on the base plate. This proved more difficult than I had imaginged as there was some "play" in the machined mount. Tightening the two grub screws could alter the spot position on the base plate by 1-2 cm. I then found it impossible to fix the LNB onto the fixed feed horn as I coiuld not get the screws in place. In the end, I put a layer of clear tape aroung the feed horn tube to make it a tight fit in the mount before uncrewed the scaler ring, attaching the LNB nad then putting it all back together again. Not perfect, but I am fairy sure that I aligned the axis to within 1cm of the center. Finally the moment of truth. I connected my Satlook spectrum analyser to the LNB, set the elevation to 37.5 degrees and rotated the dish in azimuth to lock onto a strong low band Astra 2 transponder - 10964H. After a few minutes of trying with the wrong satellite (Arabsat at 30.5 degrees east), I got a lock on Astra 2D and peaked the signal in both elevation and azimuth. Then set the LNB tilt to 9 degrees. Back in the house, connected to the Pace Skybox, I had Radio 4 on 11954H, but NO BBC1,2 or ITV! Disaster - after all this work and care what a let down. My wife went very quite. So there must be something wrong. I checked the signal strength on 10964H and found that I was getting 71.2db on the meter. I removed the LNB, put it back on the 1.2m Channel master dish and measured 75.8db. That was enougth for the day. Corviello, who has posed about his own experiences with a 3.4m Prodeline disk is visiting on Friday, so I will try again then. PJG [/QUOTE]
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Sky Digital BSkyB, Freesat & Saorsat support forum
Sky & Freesat fringe reception
A 3.7m Prodeline dish for Astra 2D
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