SatSig topic:

USALS advice

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Dec 30^th, 2008 at 5:01pm

I got a FORTECSTAR 4200 receiver, FC-90B dish and it came with a STAB HH90 motor.

Now after much cursing, grumping at the kids I have finally got the whole assembly set to point at the Hotbird Satellites.

The thing is at the moment my receiver is set to fixed antenna. This is a quick fix so my wife can have Russian TV for New Years eve. After New Year I'm going to set my box to motorised antenna. What problems can I expect?

I'm worried that once I change it to motorised and tell it to look for Hotbird that it is going to point away in the wrong direction and I'll have to start again with respect to physically twisting the antenna. Is this going to be the issue since I seem to have the elevation of teh dish sorted?

PS I hope what I have written makes sense. I'm a first time dish installer...

Dec 30^th, 2008 at 8:16pm

This page may be of some help: https://www.satsig.net/polar-mount-4.htm

Setting up a polar mount requires:
1. Calculating and then setting the motor axis angle accurately. Need to know your latitude.
2. Calculating and then setting the dish tilt angle accurately. Need to know your latitude.
3. Pointing the dish due south while leaving the motor central. Need satellite, pole star, sun angle, compass, GPS or map.

If you do 1 and 2, then, with the motor central, peak up the dish on the due south, or nearest to due south satellite, you won't be far out.

It may take several hours to achieve success so I recommend you practice at ground level using a temporary, but rock steady pole, with a clear view of the sky from low down in the south east to low down in the south west. Once you have it working and can access all the satellites then move the dish to its operational location.

Some people take many weeks to get their polar mount working. The quickest way is to set the motor and dish tilt angles indoors where you can make precision measurements. Then choose a satellite closest to due south and tune up the receiver. Offset the motor slightly sideways as needed (see angle from https://www.satsig.net/maps/satellite-tv-dish-pointing-uk-ireland.htm). Attach the assemby to the pole and rotate entire assembly till peaked up. Job finished.

Best regards, Eric.

Dec 30^th, 2008 at 9:11pm

I did 1 and 2 but to keep the wife happy for the time being I am using it as a fixed unit.

so if 1 and 2 are done all I need to do now is point my antenna unit due south then tell my unit to go find a satellite.

Sorry if I'm sounding dumb but just want to sure I have understood what you are saying.

Oh one more thing. I set the LNB polarisation for tha required to pick up Hotbird as per the instructions concerning LNB polarisation for that satellite. Once I get the motorised unit working will this matter for the other satellites?

Cheers for the help.

Dec 30^th, 2008 at 10:31pm

With the motor drive actuator stopped central (or slightly offset by pre-calculation) you need to turn the entire head unit on the pole till the head unit is accurately north-south. It helps if there is a satellite due south of you to aim for.

Once that it set then all the satellites should appear as you drive the motor.

The problem is to get the motor axis angle correct, the tilt of the dish correct and the whole mechanism accurately north-south. Quite difficult for most people - me included.

The LNB polarisation should be set to nominal. As the dish moves the polarisation will alter automatically so as to match the satellite. One slight problem is that Eutelsat and Astra satellites don't have their polarisation planes aligned with the earth axis, errors of about 3.5 and 7 deg I think, clockwise as viewed towards the satellites. Optimise for these if you watch them a lot.

Best regards, Eric.

Dec 31^st, 2008 at 12:08am

Thanks you have made things very clear and have an excellent site for new people.