SMW-OA-1400 "Jumbo"

[RimaNTSS]

Decided to make separate thread about this antenna, to collect as much as possible information, share experience of using this elderly product of Sweden, and to have some discussions.
Antenna's data-sheet is here.
On attached picture is my antenna when it was temporarily installed in yard of seller to take picture and to show to potential buyers. I did see such antenna installed at my friend's house, but he called it NOKIA (now I know why- there are no markings of the name of dish, but actuator is NOKIA, so he made the conclusion that dish is NOKIA as well). He also has said to me he likes this antenna but not very happy about performance. I will share my doubts about possibly poor performance of this dish little later.

 

[archive10]

An "almost-prime-focus". Really weird why not make it proper offset, rather than a semi-PF dish...
Anyway, good sized dish - should give good results.

No sure about the Nokia branding.
I have seen some SMW with Nokia braning on the actual reflector, so I suppose Nokia may have sold some.

 

[RimaNTSS]

So, why bad performance?! Could be several reasons.
First of all, opening angle of this antenna is about 112* , and that means that using nowadays universal LNB with standard illumination angle 70-80* does not allow to illuminate whole dish.
Secondly, seems that focal point of this dish located on the edge of LNB holder (I put red dot where F approximately located) . And if we put standard universal LNB in that holder, that will automatically mean that it's Phase center will not be located at the Focal point of the dish.
Possible solutions of situation:
- use original LNB or, at least original feedhorn attached to new LNB
- use LNB from PFA (they usually have wider illumination angle), in that case feedarm and supporting struts should also be adjusted accordingly or made new ones.
Ou, ye, I did not check yet whether LNB is pointed to the right spot!

 

[archive10]

- use original LNB or, at least original feedhorn attached to new LNB

I thought the feedhorn in the picture was an original one?
It looks very much like the original one, then hat + C120LNB should give best results.

 

[RimaNTSS]

Yes, on the picture is original feedhorn and LNB, but I did not try this antenna and LNB at all. Speaking about not-so-good performance I meant that friend of mine who has Jumbo said to me he is not happy. And he is using simple universal LNB on his antenna. I can probably visit him some day and take my LNB along to check whether performance of system improves.

 

[archive10]

Ah, I see. Will be interesting to hear the difference once you have had your hands on the feedholder

 

[RimaNTSS]

Was having party at my friend's house. He has Jumbo motorized on his roof. Unfortunately we did not have too much time to experiment with different LNBs. This is not his primary antenna, so hardware was not ready for tests, maybe next time.

 

[RimaNTSS]

Got another 2 LNBs for Jumbo dish.

 

[Anonymous_1]

@RimaNTSS : your original Feedhorn is Circular/linear or linear only ?

 

[RimaNTSS]

They have no plates inside, so I think they are linear. But I am not sure about the working frequency range, that is taking into account how old those LNBs are.

 

[Anonymous_1]

OK, thanks Rima.
mine was sold with a plate inside, same as my XD12 Depolarizer.

 

[pitussat]

The problem is reflective surface degraded: I have also the same problem, now with new nikel emc paint it's' ok

 

[RimaNTSS]

The problem is reflective surface degraded

What do you mean?! Reflective layer is located inside (under coating). How can it be degraded? Could you show some pictures?

 

[RimaNTSS]

Hi folks! Friend of mine wish to have Jumbo motorized on Diseqc motor. I know, it is 1.4m antenna and could be too big for the motor. But he still wish to try. Besides, his motor has technical possibility to turn antennas up to 1.4m (at least it is written in the manual). And Jumbo actually is not very heavy dish.
But here I need some advices&ideas how to prepare Jumbo to be mounted on the motor.
I think, that I can fix 2 metal angles to the existing frame (red lines). And then, on the some kind of hinge add small frame (in yellow) to which connect tube of the motor. Declination adjustments can be done by 2 screws (green lines). Original cross bar (horizontal one) will be removed.
As we all know, offset angle of this antenna is only 13* (almost PFA).

 

[archive10]

I think, that I can fix 2 metal angles to the existing frame (red lines). And then, on the some kind of hinge add small frame (in yellow) to which connect tube of the motor. Declination adjustments can be done by 2 screws (green lines). Original cross bar (horizontal one) will be removed.

Now, I do not wish to detract from your prosperous dabbling in new metalwork.
But as the dish in question does not have a polar mount, why not just mount the dish on the H2H motor as-is?
If you get one of the Stabs, they can be mounted with the tube pointing upwards.
With some use of an angle grinder, it should all just fit?

 

[RimaNTSS]

The problem is that I have already told about polar-mount to friend of mine, but he does not want to listen. He even got this Diseqc motor and I do not think he will buy another one.

 

[RimaNTSS]

So, my plan is to place 2 metal angle profiles (yellow line). connect to it another piece of metal (red line) and have declination adjustment along the green line. I do not have proper metal angles and also motor is not that which will be used, so this is just a modeling.
Main metal angles will be connected to the frame of the dish by 4 x halves of pipe clams (circled blue). I need some discussion here before I start to purchase and cut metal. No discussions- I make lots of mistakes :mad:

 

[archive10]

I need some discussion here before I start to purchase and cut metal.

I would consider some horizontal bracing. If you only have vertical L-bars, you might loose out on rigidity when at extremes of arc, or even in high winds.
If I may ask the, perhaps uninformed question again: What's wrong with the original Az/El mount?

 

[RimaNTSS]

What's wrong with the original Az/El mount?

It is not motorized! I think in the case of this design the center of gravity of the dish will be located on the line of turning axis, so there will not be lots of power from motor to turn antenna and also to get it out from the end-positions.

 

[RimaNTSS]

Hanged antenna to the ceiling to find out where it's center of gravity located. I think Wim will like the picture (at least part of it ;) ) I took. Why? Cuz