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VSAT technology and installation >> Dish pointing and alignment >> Question? HX50 install Iraq W3A
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Message started by raiders01 on Aug 5th, 2010 at 6:58pm

Title: Question? HX50 install Iraq W3A
Post by raiders01 on Aug 5th, 2010 at 6:58pm
I was sent here from BW, they don't seem to be very helpful with my problem.

So I'm here trying to find out what I can do with my system. Here is the problem

1. The signal strength is 73%, I know it needs to be higher.

Status: The receiver is locked
RXcode: 5
TXcode: 13

2. The system was already setup and I have no idea where to start.

3. The cables have been replaced no more then 1month ago and have been tested.

Where do I start?

Title: Re: Question? HX50
Post by Eric Johnston on Aug 5th, 2010 at 7:19pm
To improve the 73% you probably need to peak up the azimuth and elevation pointing and polarisation.

Before making any adjustments measure and write down the lengths of the elevation and azimuth screws and the polarisation angle.  Make careful drawings so that you know how your measurements relate to the physical metal parts.  That way you will be able to get back to the starting position (as of now) in the event that you lose the satellite.

Start by practicing and learning about peaking up in elevation. This is the easiest as there is no backlash. Mark one flat on the nut with black felt tip pen. Free off the upper nut so that the dish is held by the long lower nut. Measure the signal. Now lower the dish by applying one full turn (6 flats) to the lower elevation nut. Measure the signal.  Keep going till it has gone down, to below 50%. Record the signal level, X %. Now carefully raise the dish, counting one flat at a time until the signal peaks and then drops again back down to exactly X %.  Now half the number of counted flats and lower the dish to the beam centre.  You have now learned how to peak the elevation.

In azimuth open out both nuts and gently push the dish one way and move that nut till you are down to exactly Y % (some exact value under 50%).  Now swing the dish across the beam peak and adjust the nut on the other side till the level is also exactly Y%.   You can now swing the dish several times either way to rest on the nuts and you will see Y % on each side.  Put the adjuster in the middle and carefully tighten both nuts inwards by the same number of flats.

For polarisation you should set the angle by calculation.  This will be approximate.  You will need help from the hub who may ask you to alter the angle in half or 1 deg steps. Wait about 1 minute between each movement to give the hub time to measure your new polarisation isolation.  The objective is to get you into a deep cross-pol null in the centre of a 2 deg wide notch.

Where are you and what satellite are you aiming at ?

Best regards, Eric.

Title: Re: Question? HX50
Post by raiders01 on Aug 5th, 2010 at 8:02pm
Eric,
Thanks for the quick reply. I don't get this kind of support from BW.

When you say " elevation " that is the large screw in the back of the dish correct?

When you say " azimuth " that is left to right?

The polarisation is the angle of the dish ?

I'm in Iraq
Eutelsat W3A Europe at 7 degrees east orbit longitude position ( BW said this)

Like I said in the past, I'm new at this.. But I learn fast.

Thanks for the quick reply!


Title: Re: Question? HX50
Post by Eric Johnston on Aug 5th, 2010 at 10:30pm
Yes, elevation is the up and down adjustment of the big bolt using the two nuts shown below.

Mark a flat on the lower nut with felt tip pen and note the exact measurement before you adjust so you can get back if you lose the satellite and forget how many turns and flats you have applied to the lower nut.

Azimuth is sideways movement. Note measurement of the length of the free end of the side screw before you make any adjustment.

Polarisation involves turning the whole dish using a giant circular scale on the back to approx +45 deg clockwise. The required angle depends on your location. Something like this below. Read the scale. See the +45.5 in the tiny white square on the left of the picture above.
.
Don't adjust polarisation just yet, as to do so you need to calculate the correct angle, then loosen 4 bolts which will make your dish temporarily sag down - you will eventually have to find the satellite again and repeak the elevation. Leave polarisation alone for now.

Note that you are already pointed at the wanted satellite and all you need to do is make very small changes to peak up the azimuth and elevation.  If you lose the satellite go back to the original distance measurement settings.  If you can't get about 90% then it the time to start worrying about polarisation.

Best regards, Eric.

Title: Re: Polarisation setting on Hughes HX
Post by Eric Johnston on Aug 6th, 2010 at 11:07am
Polarisation setting on Hughes HX with Prodelin 1.2m dish and '505' mode-matched feed.

1a. If you have a distinct LNB module (e.g. part number NJR2184 or SPV-30, attached to the filter arm waveguide with 4 screws) then assemble the feed system like the image below.

Note that the 505 on the horn throat must always be directly away from the feed support arm.
This creates a Horizontal receive polarisation starting position when the entire dish is rotated so that the feed support arm is at the bottom.

1b. If you have a universal LNB with integrated OMT/filter (with part number PN 1501882-0002) then set the LNB connector so it sticks out sideways. Like this image below:

Note that the 505 on the horn throat must be directly away from the feed support arm.
This creates a Horizontal receive polarisation starting position when the entire dish is rotated so that the feed support arm is at the bottom.

2. Find out from your service provider the name of your downlink receive polarisation.

3. Find out from https://www.satsig.net/maps/lat-long-finder.htm what is your polarisation adjustment angle. It will be in the range -90 to +90 deg.  + means clockwise, viewed with you standing behind the dish and facing forwards towards the satellite in the sky.

4. Set the polarisation to the nominal starting position.
If Horizonal then you are already there, with the feed arm at the bottom.
If Vertical and +ve adjustment angle then turn the dish 90 deg anticlockwise.  The feed arm is now at the side.
If Vertical and -ve adjustment angle then turn the dish 90 deg clockwise.  The feed arm is now at the side.

5. Apply the adjustment amount.
If you started with the feed arm at the bottom then the scale will help, the readings start at zero.
If you started with the feed arm at the side than count the amount along the scale. The numbers may go backwards from 90 deg. It is the amount of adjustment movement that matters, not the scale reading.

Turning the dish a further 3 deg clockwise may help with Eutelsat satellites. Your hub may ask you to make tiny adjustments to get to the exact centre of the cross-pol null.

Best regards, Eric.

Title: Re: Question? HX50 install Iraq W3A
Post by raiders01 on Aug 6th, 2010 at 4:54pm
Eric,
    I'm getting there with information you give me..

It's working but I know for a fact once the winds start up once more in the sandbox this unit will lose its signal.

Were does it need to be at and it does stay. I got the signal at 84%

I know its not good, I need to work on it a little more.

Also, I had at 89%, rebooted the modem and went to 84%?

Please let me know

Title: Re: Question? HX50 install Iraq W3A
Post by europe-satellite.com on Aug 6th, 2010 at 5:23pm

raiders01 wrote on Aug 6th, 2010 at 4:54pm:
Eric,
    I'm getting there with information you give me..

It's working but I know for a fact once the winds start up once more in the sandbox this unit will lose its signal.

Were does it need to be at and it does stay. I got the signal at 84%

I know its not good, I need to work on it a little more.

Please let me know


Is above suggestion any help for you ? Use some sandbags or weld the pole on the container.

Title: Re: Question? HX50 install Iraq W3A
Post by Eric Johnston on Aug 6th, 2010 at 7:18pm
Do your best to get the mount base and pole rock solid.  This is really important for any kind of reliable service.

Then redo the azimuth / elevation peaking up.  If it is possible to get to 89% and you are down at 84% this is not good enough.  The receive side may work fine but your transmit performance will be poor as the transmit beam is narrower beamwidth than the receive beam. You need to get to the exact centre of the receive beam.

When adjusting the nuts, 1/6th of a turn (1 flat) adjustment is significant.  If the antenna base is in concrete, welded to building structure etc you have a good chance.

Best regards, Eric.

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