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Desperetly Need Help Installing Vertex RSI 9.0 m

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Nov 16th, 2008 at 9:48am  
My company has bought and install Vertex RSI 9.0 m, but still not works as 9.0 m in Rx and Tx gain.

are there any of forum members have experience installing such antenna, pls give me your suggestions.

i also look for the antenna installation procedure or installation manual, pls give me the information if you know how or where to get.

thank you.

mas_yo2q[at]yahoo[dot]com
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Eric Johnston
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Reply #1 - Nov 16th, 2008 at 11:52am  
I suggest you contact Vertex RSI for advice. † They, or their approved installers should be contracted to install it and take the responsibility of adjusting it and getting it though its acceptance testing (far-out and near-in sidelobe patterns, cross pol performance inside -1 dB tx contour, tx gain and receive G/T). †

If it is an old antenna that has been dismantled and moved I would still recommend getting Vertex RSI involved as they will have installation manuals and specialist panel alignment tools, such as theodolite, theodolite mount jig and calibrated steel marker tape, available. †Tell them the model and serial number of the dish. †Panel alignment definitely requires a Vertex RSI qualified installer with access to the master design documentation. †Note that if it is an old dish then Vertex RSI or any other antenna installer may be unwilling to commit to achieving acceptable performance, in which case you retain the financial risk and responsibility of a dud antenna, if it does not pass. You will still have to pay the installer for their efforts.

If the problem is only to do with the subreflector and its position then follow my guide at antenna sub reflector alignment. † You can do this yourself and it should take between one day to one week to do.

Best regards, Eric.
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Reply #2 - Nov 19th, 2008 at 8:24am  
Dear Eric,

Thank you for your advise. I have contacted Vertex RSI recently, but as your saying, they asked us to pay for the copy of installation procedure, which I think my company would not agree to pay.

do you have guidance in installing the reflectors ?

Best Regards,
Yoyok
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Eric Johnston
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Reply #3 - Nov 19th, 2008 at 10:21am  
I am not happy to give you any advice as you are likely to permanently distort your antenna and make it useless.

Installing such a dish is a skilled job requiring the Vertex instruction manual and an experienced antenna engineer, theodolite, jigs, tools, test equipment etc.

Sorry,

Best regards, Eric.
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Reply #4 - Feb 27th, 2009 at 6:24pm  
Quote:
My company has bought and install Vertex RSI 9.0 m, but still not works as 9.0 m in Rx and Tx gain.
mas_yo2q[at]yahoo[dot]com


The antenna will need to be Theodolite aligned, once they get over 4M reflectors go from reasonably easy to difficult and beyond. Installing a 9M take years of training.

I can come over and tell you what's wrong with it - but I doubt i will be able to fix it if the reflector is out of shape.

If it's a case of aligning the sub-reflector then i can do this but if the feed is not 100% in the right place it will never perform like a 9M.

You say the gain is low - how low is it ?
How have you tested it ?
Do you have any off-axis (sidelobe) patterns ?

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Eric Johnston
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Reply #5 - Feb 27th, 2009 at 11:54pm  
Mik is quite right.

Installing any large dish like 9m dia requires great skill. †

A small Ku band dish, like a 1.2m or 1.8m VSAT starts off with a profile accuracy of better than 1.5mm and must not be distorted on installation. †A heavy LNB/BUC can pull the sides of the dish forwards. †Failing to correctly tension the short rear side struts on a 1.2m offset VSAT dish can reduce transmit gain by more than 3 dB. Read about getting a VSAT dish rim flat using fishing line.

A medium sized dish such as 2.4m, 3.7m or 4.5m can sometimes have its panels set up with fishing lines. See parabolic dish panel alignment and sub-reflector alignment

A large dish, like 9m dia, has many panels and with the dish facing upwards you need to set all the panel reference points the same, +/-1mm relative to the assembly reference measurements/angles, during the initial dish assembly and also have the feed axis exactly upright and in the middle. †A theodolite is essential. †Then tilt the dish to its operational angle and remeasure the mm errors up or down all the way round at the panel reference points. †You will find a reasonably smooth curve; the sides of the dish tend to push out a few mm and the top falls down a bit. †Put the dish back upwards and apply reverse adjustments to all points. †Then aim the dish at the wanted satellite and align the subreflector. †

Pay for Mik to come and see what he can do for the subreflector, but be ready to accept that if the dish itself is distorted or the hub and feed not upright in the middle then it will not pass its satellite acceptance tests.  At the hub there will be a machined ring of bolts where the ribs or panel inner ends attach. The plane of this ring must be at right angles to the feed axis and parallel to the planes through all similar panel reference targets (incuding the outer rim of the dish). 

If you have sidelobe patterns please send them to me eric@satsig.net and I will put them here to see.

As I said above I cannot give you advice about your specific dish as without the installation manual and expert help you are likely to permanently distort your antenna and make it useless. †Sorry. †It is not good for my reputation to be associated with a failed large dish assembly !

Best regards. Eric.
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« Last Edit: Mar 3rd, 2009 at 1:09pm by Eric Johnston »  
 
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Reply #6 - Mar 3rd, 2009 at 12:33pm  
Dear Sir,

The Rx and Tx problems can from feed loss or antenna installation.

As Eric and Mik say, if its problem from antenna installation that mean you get a big problem.

For check your installation result, you must already done a pattern test to satellite provider, are you?

If a pattern test result is Ok, that mean your antenna installation is Ok. So the problem may be from feed loss.

Actually from a pattern test, you must know if your feed is loss if you done a pattern test correctly.

We are from PT Teleforindo Asia base on Jakarta may be can help your company to find out where the problem is and try to correct it with reasonable price.
We have an experience for installation and maintenance a big vsat antenna.

Please donít doubt to contact us.


Regards,

Ajie.
PT Teleforindo Asia
www.teleforindo.com
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Reply #7 - May 22nd, 2009 at 7:50am  
hi all,

sorry for late reply.
i'd like to inform you that my 9.0 m antenna is working nicely since the end of 2008.

thank you for your wonderful support.

Best Regards,
Yoyok
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Reply #8 - May 24th, 2009 at 8:10am  
Dear Yoyok,

Can you please tell us how was it fixed?

Kind Regards,
Nimrod
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Reply #9 - May 25th, 2009 at 6:15am  
Dear Nimrod,

my installers bring down and recheck all the antenna components [since it was a used antenna], including the feedhorn and all the dishes, make sure if they are all ok and then bring them up again for installation and adjusment.
it worked.

i must say that they were a pretty tough installers, they were divided into 2 shifts and worked day and night to solve the problem.

best regards,
yoyok
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