Just Sharing This Coming to a forum near you soon - mobile dish test rig

[a33]

@PrvtN00b :
Well, I assume there ARE dishes out there with accurate position for the LNB holder and proper LNB-aiming.

But as this is (just) an assumption, measuring and checking is very usefull, when you want to get the most out of your dish!

For a paraboloid dish (parabolic both vertically and horizontally) with a flat face, the best way to measure it is finding three measures: hight and width of (the working area of) the dish, and exact depth at the middle; and then let a calculator do the work.

Parabola6 by Strannik is a good calculator, and so is my calculation spreadsheet (results for CM180 shown in an above post).
Don't use Parabola Calculator 2.0 though, or the Satsig calculator. They use the deepest point measurement for calculation, which in theory is OK (see also my calculator), but these two calculators alas give wrong outcomes!


Knowing the exact offset angle of your dish also gives you the opportunity to set the dish elevation by measuring the angle of the dish face. That is very usefull when setting declination towards due south/north, with no satellite at exactly that direction.

Greetz,
A33

 

[Channel Hopper]

in other words, we are not even using the full potential of these dishes at all??

thanks.

The CM design, like many others have no user adjustments because they have been tested and approved for use in the VSAT industry for receive/transmit purposes.
John's dish, whilst using the same reflector has the consumer type feedarms and clamping, I doubt the manufacturer is at fault, but it might take another user of the same model to confirm this.

If somebody on the forum does own the commercial version with the separate backplate and single boom, and takes measurements in a similar fashion, then it could provide some reassurance.

 

[John]

Finished tweaking illumination mapping on the 1.8 CM using stock arms and stock non adjustable plastic lnb holder but had to alter fixing points and lengths of side arms to achieve this. Awaiting Rimants Inox adjustable lnb holder which will help enormously for future change-over of different lnb's / feeds for different bands.
Have got all the ref: measurements dialed in correctly - which is not a 5 minute job, as opposed to the stock measurements. Here's a quick vid showing present mapping with a hand turned laser pointer in the lnb holder slightly loosed off - which causes a bit of pointer shake as i alter my grip on the protruding 40mm tube out the back of the lnb holder but you get the idea.
Apologies for dish washer noise at the end chucking it's water out into the nearby drain and the setting afternoon sun that didn't help with the lighting of the operation.
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[RimaNTSS]

Seems that you made video Private, so, it is not possible to see it, at least at my end.

 

[John]

Seems that you made video Private, so, it is not possible to see it, at least at my end.

I'll double check Rimants and alter it

 

[John]

I'll double check Rimants and alter it

Try it now Rimants - changed it to 'Public'

 

[RimaNTSS]

Much better now @John . I am just wondering if you are shooting the movie, who is moving in front of the dish? Just kidding. Please continue!

 

[Channel Hopper]

Good thing you don't have cats.

 

[PrvtN00b]

Good thing you don't have cats.

I guess is for the red dot...

 

[John]

Good thing you don't have cats.

Ha ha - had to think about that for a while before the penny dropped - it also works with dogs

 

[John]

... 1st day out for the new kid on the block using ref: measurements for feed positioning & illumination mapping.
Pretty good results with no tweaking apart from skew & considering the lnb and most of the dish is only 150mm off the ground so subject to some ground noise perhaps - looking at 63° West data using a cheap 'Blazer' pll universal lnb for about £8.
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[John]

... This little box turned up today for use on the mobile test rig

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[John]

... It's one of Rimants Inox adjustable lnb holders.
A very nicely made holder it is too.
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[PrvtN00b]

... It's one of Rimants Inox adjustable lnb holders.
A very nicely made holder it is too.
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View attachment 126413

The best, I have a few of them over here in Central America, Panama, made by RimaNTSS

 

[John]

... I thought i would make better use of a 1.2 mtr Precision PF reflector that was hanging about in the garage along with the 1.8 CM reflector before it got grafted onto the Test Rig set-up.
Iv'e knocked up a 'quick release' idea to attach the 1.2 in front of the 1.8. Iv'e got some Ku to Ka feed experiments to look at soon and the 1.2 Precision is an ideal candidate.
As the Test Rig is a purely functional device, cosmetics don't come into it.
I started off by quickly fabricating two side brackets to attach to the upper side points of the 1.8 CM - the rest should be easy to follow from the pics.
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[nelson_b]

Yes .... Liking it ....