SatSig topic:

HX Issue: resolved: LNB option set to Pure

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Apr 14^th, 2009 at 4:31pm

If anyone can help out it would be much appreciated. I am having issues with the new HX50 I got from Wafa. I can not get any stronger signal than 29, I am using the HX modem and LNB I got from them new. I am using an old Hughes dish and feed horn from a HN7000s that I used before.

My location is N 36deg 48min E 42deg 4min

I am suppose to aim at Eutelsat W3 at 7E

By using the https://www.wafa.ae/en/vsat/support/toolbox/satfinder/

It tells me:

Dish azmuth of 224.5 mag
Elevation 33.8
Polarization 37.6

This is exactly what my dish is aimed at right now, when my 7000 is hooked up it reads 92 signal. But if I hook up the HX I get 29.

Wafa support says I should aim it at
Azimuth - 237
Elevation - 29
Polarization - 43

So what is correct?

I have contacted Wafa to make sure the info in my RPR is correct and they say it is. The support guys told me this

“Also kindly align the dish with heigher height may be at roof or by using pillars ,as HX and 7000 are entirely different ,to receive signal the dish should be placed with the greater height.Please make this chnages and update us with teh screenshot od dish ,system status .”

Maybe I don’t total understand how satellites work but how can putting my dish on the roof make it work, if my 7000 is get signal fine from the same satellite.

Apr 14^th, 2009 at 7:36pm

Unless you were aimed at the sun, a peaked up figure of 29 means you are pointed at any powerful satellite. The scale from 0 to 29 just means noise power. 29 is the maximum reading. The scale will not go above 29 until you are on the correct satellite, correct polarisation, with correct LNB Local Oscillator frequency and correct modem tuning configuration. Scale readings from 30 to 100 mean wanted signal quality.

If the wanted satellite is at very low beam elevation angle and your dish cannot see the satellite due to an obstruction such as fence, building or trees then raising the dish height or moving to a different location is appropriate. If you have set the correct beam elevation angle you may look towards the satellite by putting put your head behind and below the lower edge of the dish and sighting in the direction of the feed horn. Can you see the sky ? Alternatively, to evaluate a location, have two people. One holds a sloping plank of wood with an inclinometer and sets up the beam elevation angle. The other person sights along the wood. Here is how to make an inclinometer.

Regarding pointing angles I get Az=224.6 magnetic, Elevation=33.7 Polarisation +37.5 These are the same as the WAFA calculator page, which is to be expected since I note they have copied my software code verbatim ! See my Dish pointing angle calculator for Iraq

What WAFA should tell you is the NAME of the downlink polarisation. If it is horizontal polarisation the set your LNB arm upwards initially, then turn it 37.5 deg clockwise, while you are facing towards the satellite in the sky. Here is a picture of something similar, but with +46 clockwise adjustment applied:

You are welcome to send me a copy of your configuration document. eric@satsig.net

Also tell me the exact type/model number of your LNB. It would be reassuring to know that this calculation is correct:
Modem tuning frequency + LNB local oscillator frequency = Satellite frequency.

Example frequency calculation:
Modem tuning = 11272 (100kHz) = 1127.2 MHz.
Modem 1127.2 MHz + LNB LO 9750 MHz = 10877.2 MHz satellite.

A copy screen shot of your configuration page might be helpful also.

Best regards, Eric.

Apr 15^th, 2009 at 6:08am

The dish is already pointing at the satellite in question (W3A), my 7000 works fine on the same dish, when I swap out the LNB and modem to the HX I get 29.

I tried everything before posting here, I already used your inclinometer, worked great, thanks.

So the dish is aimed right, it the settings of the modem that are keeping it from locking.

Apr 15^th, 2009 at 7:34am

I will get hold of Wafa and we will solve this issue

A Walker

Apr 15^th, 2009 at 8:57am

Hi Josh
Seems you have got an SQF of 92 now and 1 parameter on the system has to be changed and we are ready to go.

Apr 15^th, 2009 at 9:56am

Well look at that I got a signal of 92 with out putting the dish way up in the air. Actually I did nothing to the dish, I changed the type of LNB in the settings and now its at 92.

I had it on, what brand it was but I changed it to "Pure" and then it got signal.

Apr 15^th, 2009 at 11:17am

Many thanks for reporting that you have identified and fixed the problem, and that all is now well.

LNBs come with various local oscillator frequencies, e.g. 9.75, 10, 10.6, 11.3 GHz according to in what block of Ku band frequency is the wanted satellite carrier, which may be anywhere from 10.7 to 12.75 GHz.

Some LNBs have multiple selectable local oscillator frequencies.

You need the correct local oscillator frequency to convert the satellite frequency down to the much lower L band tuning frequency in the modem.

The selectable "universal" type LNBs can be controlled from the modem using alternative DC supply voltages: 13V or 19V, or by turning a 22kHz tone on or off. The arrangments vary with model number and manufacturer. One combined LNB/BUC module (TRIA) has an external dongle and can switch amongst many LO frequencies and even change between co-pol and x-pol operation.

When you install a new site make sure that the downlink satellite polarisation name, the satellite carrier frequency, the LNB local oscillator frequency and the modem tuning frequency are all documented.

Best regards, Eric.