Make Gregorian dish

[samoloko]

Some time ago i was surching for the best lnb position at a Triax TDS 64 , made a tool to messure the openings angle of a BU .
I dont know its the correct way to messure it but it came out to 55º , also in other brands lnb's . (red lines)
But since there are rumors that the receiving point in the lnb is in the center of a ball shaped aerea of ± 25 mm (according to the KU wave lenght) I draw the bleu lines .

does anyone measured angle which Is between red lines on a Skyware feedhorn on channel master 1.2 / 1.8 / 2.4

 

[archive10]

Mosr akyware feedhorns are for 0.6 f/D dishes as mosr skywarevdishes are 0.6 f/D.
Perhaps rimantss can caculate the angle somehow.
But your best bet is to try various things and see what works best.
Apart from several variants of skyware feedhorns, there are also gibertini, smw and laminas feeds which are all for 0.5 - 0.65 or thereabouts.
Many of them afe reasonably priced, if you cant borrow somewhere.

 

[RimaNTSS]

I do not know how to measure illumination angle of feedhorn. I think can be only calculated, not measured. But how? Who know!
Assuming that producer of CM dishes made also matching feedhorns to them, we can state that feedhorn's illumination angle is equals to opening angle of the dish. But antenna's opening angle can be easily calculated. So, if we have 80* opening angle of antenna than it's feedhorn has 80* illumination angle. Degrees, of course, could be re-calculated to f/d ratio.

 

[archive10]

Mosr akyware feedhorns are for 0.6 f/D dishes as mosr skywarevdishes are 0.6 f/D.
Perhaps rimantss can caculate the angle somehow.
But your best bet is to try various things and see what works best.
Apart from several variants of skyware feedhorns, there are also gibertini, smw and laminas feeds which are all for 0.5 - 0.65 or thereabouts.
Many of them afe reasonably priced, if you cant borrow somewhere.

Sorry for the spelling - I shall stop using touch-screen devices sometime soon, as they are not compatible with my fingers, it seems...

 

[RimaNTSS]

OK, I did it on bigger dish and do not see a reason why it will not work on smaller dish, in my case CM120. There is the plan:
- make new feedarms. Side ones will be adjustable in length, so the bottom one can be placed at any angle needed;
- feedarms will be connected to the side of the main mirror. Yes, some new holes will be made there.
- Material.... you know ;)
Will probably make some additional LNB holders (when SUB is removed) to have this dish fitted with multifeed.
I am not in hurry, so process will be slow and with some pictures on the way.

 

[RimaNTSS]

Of course, I am not going to make SUB (this is not so easy), will use SUB and feedhorn from Fibo90. And some INOX for the feedarms.

 

[RimaNTSS]

For side arms I think will be enough to put 20 x 30mm 1mm plates (red) with 3 holes (white). 2 holes for rivets and 1 x 6mm hole to put 6mm bolt through it and attach side arms to it. I do not think I need something more massive for this.

 

[RimaNTSS]

Made 4 plates for fixing side arms. Not perfect, but who is perfect?!

 

[RimaNTSS]

And for bottom arm not so easy. There should be hinge made to hold arm and let it turning around axis (yellow). Can look something like this:

 

[RimaNTSS]

Attached new side-feedarm place, only from one side of the dish as the rain started

 

[RimaNTSS]

Made bottom hinge. Used material I have on hands, so lots of angle-grinding. 1 and 2 were one part originally, cut them apart and made part #2 more narrow, to fit bottom feedarm. In feedarm inserted 10mm outer diameter and 8mm inner diameter pipe to work like bearing

 

[Captain Jack]

Love your work!

 

[RimaNTSS]

Here I need some ideas: How to make join (circled yellow) it to be movable across button feedarm and when it is tighten then nothing moves.

 

[Archived-1]

Here I need some ideas: How to make join (circled yellow) it to be movable across button feedarm and when it is tighten then nothing moves.

Could you not sleeve over the top of it Rimants with two welded nuts for locking it off

 

[RimaNTSS]

Martin, thanks, could you make some simple sketch of your idea?
Parts for hinge attaching are ready, but it is raining , can not continue.

 

[Archived-1]

I am rubbish at explaining things Rimants , I hope you can make some sense of this ?

 

[Archived-1]

It would have to be something like this to allow the sleeve to fit over the welded bolt.

 

[RimaNTSS]

Yesterday was raining but today is already too hot .... and after a bottle whisky last night... Anyway, finished the hinge.

 

[RimaNTSS]

Finished with cross-bar. Side-arms are next to be made. Lengths about 90cm.

 

[RimaNTSS]

Made couple of sidearms, but got an issue- have to bend their ends to certain angle. Perhaps I need to find another way how to install side-arms.