Help me please HX50 W3A Madagascar

Hello!

First of all, dont give up yet. pointing a dish, especially in Ku band, without proper equipment for the first time is not easy. If you or the service provider can not efford sending someone to the site and help you, please consider the following notes.

1. About elevation - The elevation you mentioned is the true elevation. But most probably your dish has an offset, probably around 22 degrees. Plus, you placed the inclinometer at the right place, but as the bar behind the dish is perpendicular to the looking angle, so calculating with the offset as well, you need to look for readings in your inclinometer of around 72 degrees. This should be your starting point. You can see that when you elevate the dish to this reading, the dish is mechanically elevated around 20 degrees ( 18 ) above the horizon.
2. Once you are there, you need to do the following:
- Either you connect your satmeter, and make sure and double sure and triple sure you have put the right parameters in it.
- Or you connect your modem - and again, you make sure that the settings are all good there.
3. Take a deep breath, be patiant and do the following:
- point the dish more or less to the azimuth, and chech your meter. Then, start move it left and right, VERY slowly (it is Ku band), and every now and then make sure the elevation is still the same. If your mast is not 100% vertical, when you will move the dish on azimuth the elevation will be changed.
Anyway, sweep very gently and see if you can get anything.
Then, change elevation 1 deg (either up or down), and again sweep azimuth axis. Repeat this action slowly, with calm, and eventually you will probably get the bird. Also, make sure you are on the right polarity. It wouldnt be a bad idea to try the other polartity as well, from my experience, many times NOC guys are sitting very comfortably in their airconditioned room and they have no idea what is the polarity needed.

Another point worth checking is to make sure you are under the coverage of the satellite. In SE Madagascar W3A is not so powerful as in Antanarivo for example. Make sure with the NOC that you are supposed to be in a coverage area with your dish.

Another point is to make sure that your line of sight it clear. For your looking angle, more or less if you have a tree 10m high and 10m away from the dish, for example, it will block you. Make sure your line of sight is clear.

If all this fail - we will be able to assist you, we can dispatch and engineer from Antanarivo.

Good luck,
Nimrod

Good Morning Sir,
I have contacted WAFA on your behalf and discussed your case with them. I have reviewed the photographs and can see that one of our RF engineers mentioned the below:

"You need to move the marker on the TX BUC to +56 on the degree scale at the front of the BUC.
Also looking at the skew on the antenna I think your antenna should be a lot higher, it is 38 degrees of elevation to the satellite. What I suggest is you start the antenna higher than 38 degrees and work the antenna down a degree at a time panning 30 degrees east and then west of 293 degrees azimuth."

Did you implement the above recommendations? Also; please confirm the P/N number of the receive LNB.

This image, from a CD supplied by WAFA, shows a Hughes Universal OMT/LNB Part number 1501882-0002 10.95-12.75 GHz.



The image shows an incorrect position for the single tick mark on the adapter tube. The single tick mark must be always be directly away from the feed support arm.

As shown, the LNB is oriented so that receive polarisation is exactly vertical and transmit polarisation is exactly horizontal.   This is the starting position if the wanted receive polarisation is Vertical name.

I am assuming a 1.8m dish with the feed support arm fixed at the bottom.

I've just spoken with Bentley Walker and they say that you should be receiving Horizontal name polarisation (W3A 7E Southern Africa, HX service).  This means that you must turn the whole Feed/LNB/BUC assembly, as shown in the picture, 90 deg so that the LNB connector points out horiziontally at the side. The labels on the LNB will be upwards. The single tick mark will be upwards - good ! This is now the correct starting position for Horizontal receive polarisation.  

For Madagascar and W3A satellite at 7 E a polarisation adjustment now needs to be applied.  This is -59 deg anti-clockwise as viewed facing forwards towards the satellite in the sky.  The satellite is towards the north west.

Turn the LNB and BUC (but not the feed horn or spacer tube) -59 deg anticlockwise, as viewed facing towards the satellite in the sky.  Undo the 6 screws and reattach the circular flange so that the single tick mark remains near the top,  as best you can. The 12 holes will mean you can get it within +/- 15 deg. That will have to do.

====

Using
https://www.satsig.net/maps/satellite-tv-dish-pointing-south-africa.htm
This shows the dish pointing for Madagascar and W3A at 7 east.


Best regards, Eric.

Beam elevation
WAFA have told me that your dish is Prodelin Type 1183/1184
Assembly manuals for all Prodelin antennas are listed here https://www.gdsatcom.com/vsat_assembly.php
Both these designs have a beam elevation offset angle of 22.3 deg
If you set the front face of the dish vertical the beam elevation is 22.3 deg.

In order to get the beam elevation up to 38.5 deg you need to tip the top of the dish backwards by an amount of 38.5 - 22.3 = 16.2 deg.

Check the initial verticality of the front of the dish using a plumb bob.
Put an inclinometer at the back and tilt backwards by an amount of 16.2 deg.
Make an inclinometer if necessary: https://www.satsig.net/pointing/how-to-make-inclinometer.htm

Polarisation
You are supposed to be receiving Horizontal name polarisation.  Start with the Hughes Universal LNB F connector sticking out directly sideways, on the right hand side, as viewed with you standing behind the dish and facing forwards towards the satellite in the sky (to the north west).
Stage 2 of the polarisation setting is to apply the adjustment of minus -59 deg. Lift the LNB upwards, anticlockwise by an amount of -59 deg.  Use the scale tick marks to measure the amount. If the numbers go backwards from 90 ignore the numbers; it is the amount and direction of adjustment that matters.

HX50 modem configuration
Have you input the carrier frequency and symbol rate etc from your configuration sheet ?  Once you have done this, simply swing the dish boldly sideways to find the satellite. If nothing found, go up 0.5 deg and swing again. The various satellites are in a sloping diagonal line across the sky, down in the north west and high up at due north.

Today (10 Sept 2011) and for the next 9 days the sun's path across the sky passes through the positions of satellites. Is your dish illuminated by the sun in the afternoon and until what time ?  What time is sunset ?

You may get signal power readings of up to 29 initially (on any satellite), and then up to 100 once your modem locks to the wanted carrier, i.e. on the correct satellite, correct polarisation and with correct tuning config in the HX modem.
wxw
Best regards, Eric.