SatSig topic:

Need help aligning satellite Kirkuk Iraq

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Feb 1^st, 2007 at 10:18am

I am aiming at AM1 which is 187 AZ from my location and 48 Degrees EL. My Pol is set at +6

One of my major concerns are, I am using a Bentley Walker / Direcway 1.2M dish, but I cannot positively identify the model of my dish to verify my Offset for the EL. I think it is a Prodelin. I can email you pictures to show you, maybe you can help.

I tried aiming with a 17 degree offset, but am not really getting anything. We are sweeping slowly, with 5-10 second pauses towards our aiming point, when we have fluctuations. We are sweeping about 20 degrees on both sides of the propsed AZ.

I do notice that when I start with an EL of 31 (48-17), we get a stronger reading as we go down in EL. So maybe my offset is 22? Even still we continue sweeping until around 22 EL....nothing.

Should I clean my Dish? Does the feedcone itself affect the shot? Does it matter how close or far the feedcone is to the dish?

Feb 1^st, 2007 at 11:23am

Elevation: Put a thin strip of wood rested across the top of the feed horn and under the bottom edge of the dish. The slope of that wood is then, approximately, the true beam direction and elevation angle. Adjust to 48.6 deg.

The distance from the feed to the dish does matter. If it is wrong the beam will be out of focus and wider than it should be. The effect is low gain performance and interference from the next satellites on either side, but it is likely the system will still work in clear sky conditions (but not in rain). You should be able to find the satellite, even if the dish is out of focus. I once installed a Direcway transmit/receive outdoor module which had a number of alternative fixture positions. As delivered pre-assembled, the focus was bad and the wanted signal had an interferer superimposed on it from the adjacent satellite (as seen on spectrum analyser and low receive quality on the modem). It took me several hours to resolve correct focus by trial and error changes.

If the dish has short side struts at the back note that their purpose is to stop the sides of the dish being distorted forwards or backwards by the weight of the feed assembly. The rear short side struts have slightly elongated holes to allow some adjustment. Pull or push the dish edge as you tighten the nuts.

The front of the dish should be flat to 2mm using crossed fishing lines up/down and across.

Best regards, Eric.