OTHER Unknown Dish

[Hoops ❁]

I have an opportunity to obtain a commercial Ku dish that was left behind by Safeway. The dish is actually 2 pieces, which I have never seen before. I have seen Prodelins before but they were 1 piece.

This dish is a monster and appears to be about 8 feet. The pipe is around 7 inches. The good thing is I can break it down into 2 pieces.

Any idea on what make this dish is?

Hi, i recently got this exact same dish but it came without the feed rods and the lnb holder rod, i intend to fabricate the rods but i don't know the right lengths. Can you please measure the length of the rods of your dish so i can use that as a guide to fabricate mine. Thanks

 

[Hoops ❁]

I have 3 Prodelin dishes here. I fabricated mounts and converted to C band, 2 of them have some added Ku band LNBFs for nearby satellites. I measured the focal points from the original feedhorns and tweaked as necessary for optimum signal.

Hi, can you help me the the lengths of the lnb holder and the side feed rods for 2.4m prodelin. I recently got the reflector without the rods, i want to fabricate them

 

[Hoops ❁]

I also had 2 x 1.8m Prodelin dishes and liked them a lot, as they are very good quality ones. I personally think that it is nearly impossible (very hard at least) to find position of the focal point of the dish by experiments. More proper way to do that is calculation.
there are no difference between LNB for offset and PFA, I have no idea why Inverto made such indication. Another case is LNBF for an offset dish and LNBF for PFA... they are not exchangeable (they will work but performance will be bad). So Inverto Black Pro fitted to Prodelin feedhorn should give perfect reception results.

Hi can you help me with the length of the 3 rods holding the lnb on the 2.4m prodelin please

 

[RimaNTSS]

length of the 3 rods holding the lnb on the 2.4m prodelin

Before you cut the metal find out where the Focal point (FP) of the dish is located. You also need to know what is the offset angle of the dish.
So, when you know the position of the FP, make sure the feedarms and the LNB-holder place the LNB in such a way that it's Phase center is co-located with the FP.
Do you know parameters of your antenna, such as:
- position of the FP;
- opening angle;
- offset angle
???
Without knowing those parameters I would not recommend to make any feedarms and LNB-holders.

 

[Hoops ❁]

Before you cut the metal find out where the Focal point (FP) of the dish is located. You also need to know what is the offset angle of the dish.
So, when you know the position of the FP, make sure the feedarms and the LNB-holder place the LNB in such a way that it's Phase center is co-located with the FP.
Do you know parameters of your antenna, such as:
- position of the FP;
- opening angle;
- offset angle
???
Without knowing those parameters I would not recommend to make any feedarms and LNB-holders.

Thanks for the reply, i do no know those parameters, any ideas how i can them? Please.
I just found out that the offset angle is 22.3°

 

[RimaNTSS]

any ideas how i can them?

As usually, measure the working area of the dish precisely, width, height and depth. An then use measured data to calculate all needed parameters. Could you show couple of pictures of the dish you got?

 

[Hoops ❁]

As usually, measure the working area of the dish precisely, width, height and depth. An then use measured data to calculate all needed parameters. Could you show couple of pictures of the dish you got?

Here is a picture

 

[RimaNTSS]

Here is a picture

There are feedarms & LNB-holder on the picture. Why do you need new ones?

 

[Hoops ❁]

There are feedarms & LNB-holder on the picture. Why do you need new ones?

I made those, they don't work right hence i need to actual measurements

 

[RimaNTSS]

OK, I see. Then I would suggest you need to measure your dish and then calculate parameters we spoke earlier. After you know parameters of antenna you can make perfect feedarms. Actually, it is better to make extendable feedarms, so you will be able to change position of the LNB later.

 

[FTA4PA]

Hi can you help me with the length of the 3 rods holding the lnb on the 2.4m prodelin

i do no know those parameters, any ideas how i can them?

You may find the program, Parabola Calculator 2.0, helpful. Once installed select the WiFi Calculations tab, then choose either Centered or Offset Feedhorn depending on your dish type and enter the required measurements. You can download it here:

Parabola Calculator version 2.0

mscir.tripod.com

P.S. I've run this in Windows XP, XP in a Virtualbox under Linux and also directly in Linux (as long as you extract the contents of the VB6 runtime to the directory where the parabola calculator is located). I never installed this under newer versions of Windows as I switched to Linux but it should work fine.

 

[primestar31]

Can you post some clear photos of the BACK of the dish, especially if there's a MOLD number stamped into it, and if so, make sure we can see that mold number clearly?

 

[a33]

You may find the program, Parabola Calculator 2.0, helpful.

It is helpful only in the sense, that the part for prime focus dishes is indeed very much OK.

The WIFI/offset dish part of that calculator, however, is inaccurate in two senses:

1. It ASSUMES that vertex is at bottom of the dish, and calculates with that untested assumption, and mentions the vertex at bottom as a CONCLUSION. Oh dear!
Needless to say the results cannot be accurate at all; only in the very very rare cases that the vertex is indeed exactly at the bottom of the dish.

2. It gives two differing angle for the opening angle to the LNB: horizontal and vertical. This is nonsense, and a sign that the geometry of the offset dish is not understood completely.

So parabola calculator 2.0 can be binned, as far as I am concerned.
I've mentioned this on several forums repeatedly; in this forum eg here:

finding dish focal point. ( in Hindi)

found this video about finding solid dish focal point. Its in Hindi but you get the idea. FF to 7:20 minutes. i gave it a fast try, it should work. opinions/ideas/suggestions..

www.satelliteguys.us

Hughes Net Dish

I just happened to spot this dish at a local quick stop store and I was wondering if it could be used as a prime focus Ku Dish? It measures 38.75 inches across, but it's only 2.75 inches deep. I did the math and came up with a focal distance of 34.14 inches. It was previously used as a WV...

www.satelliteguys.us

NB Contrary to what I posted in the first link, Parabola6 has no confusing string value; I was the one that was confused there! Sorry for that.


Why use an inaccurate calculator, when good ones are also available?
The good/accurate ones are:
-Parabola6 (with beautiful graphics)
-My own spreadsheet calculator (A33) (with multiple input possibities, even for paraboloid non-flat dish face dishes)
-A french spreadsheet calculator from 2001, by A6AGR I believe (basics)

greetz,
A33

 

[Hoops ❁]

You may find the program, Parabola Calculator 2.0, helpful. Once installed select the WiFi Calculations tab, then choose either Centered or Offset Feedhorn depending on your dish type and enter the required measurements. You can download it here:

Parabola Calculator version 2.0

mscir.tripod.com

P.S. I've run this in Windows XP, XP in a Virtualbox under Linux and also directly in Linux (as long as you extract the contents of the VB6 runtime to the directory where the parabola calculator is located). I never installed this under newer versions of Windows as I switched to Linux but it should work fine.

Thanks, i will give it a try.

 

[Hoops ❁]

Can you post some clear photos of the BACK of the dish, especially if there's a MOLD number stamped into it, and if so, make sure we can see that mold number clearly?

Here are the pictures, the only stamped text on the dish is 2.4m reflector

 

[RimaNTSS]

It looks like prime focus antenna (PFA) to me.

 

[primestar31]

This appears to be the manual, perhaps it'll help.

https://gdmissionsystems.com/-/media/General-Dynamics/Satcom/PDF/Antennas/VSAT-Products/Technical-Documentation/Assembly-Manuals/4096-476.ashx?la=en&hash=6D3586E2B0AD01E5FA6B676D256067A8D898E72A

 

[a33]

So, assuming the dish face is perfectly flat (is it?), measure width and hight to a millimeter precision, and depth at the center if possible to a tenth of a mm (all measures from the working area of the dish, without the rim!), and we'll give you all the specs.

Or download a program like Parabola6 yourself, and do the calculation yourself.

Would it be the same as a 2.4m Channel Master?

Greetz,
A33

 

[st1]

It looks like prime focus antenna (PFA) to me.

Well, some of those Prodelin design do look a lot of prime focus dishes (nudge, nudge, do-you-remeber, eh?)

But it is definitely a 1251 offset dish. And I believe it's a 0.6 f/D one.
At least the reflector seemingly used to be part of a 1251 antenna.
(But the removal of the Prodeiln name and typenumber from the model designator make you wonder if it's actually a re-mould?)

The mount is not original (and note that it seems broken in th left-hand side).

That is not to say it won't do the job - if properly made, a re-enabling of a reflector will work fine. You just need to focus the LNB.

Follow instructions as above, then make feee-holding arms.
OR
If you want the "official way", make arms according to attached PDF.
Use the measurements of the 240cm 0.6 f/D Ku band specs.
Make arms that put the LNB in that position.

 

[Magic Static]

If you want the "official way", make arms according to attached PDF.
Use the measurements of the 240cm 0.6 f/D Ku band specs.
Make arms that put the LNB in that position.

Provided you have the official feed horn to measure with,