Tests of 120cm antennas

[Riverblue]

And we can get them made by ourselves out of.... you know what material

Wood? . . . . . . . Plastic? . . . . . . . Cardboard?

 

[RimaNTSS]

Nope! One more try!
OK, OK, could be any suitable material, but.... painted by INOX paint

 

[Riverblue]

What could it be??????? . . . . . . . . . . . . . . . No . . . . . Not INOX!!!!

 

[jase1]

I thought that there was only one type of feed arm assembly for the "Type 120" dish that us hobbyists generally have, those that fix through the dish and link up at the lnb holder. Like so;
View attachment 73771

They are fixed by bolts through the back;

View attachment 73772

But now I've spotted these images of a slightly different arrangement, note the sidearms and how they are fixed to the lnb holder;

View attachment 73773

View attachment 73774

It still looks like it is aimed at a central position to me! Also it looks like it gives more clearance for the attached feed horn.
Anyones else have feed arms like this on their Channel Master dish, or has seen one before? Does anyone think that the fact that it is probably (according to the logo!) an "Andrews" dish make any difference (which would make it newer!). Thought that they were all the same?

Is this the same LNB holder? https://www.satellites.co.uk/forums/threads/channel-master-1m.149581/
Are these standard fit with the Tooway dish?
Different side arms bolted to the outside instead of located in the holes?

 

[Riverblue]

No, they're a slightly different version of the black ones in my post 192. The side arms still fit inside the holder, but are fixed by bolts from the side as opposed to fixing through the rear.

 

[Archived-1]

Like Rimants says we can make our own, i personally will make them for anyone who wants one, once all is well with my own, too much weight with inox and 3/4 lnb on it, good grade aluminium might be the way to go with this

 

[RimaNTSS]

too much weight with inox and 3/4 lnb on it, good grade aluminium might be the way to go with this

Martin! It depends on pipe wall thickness, if it something like 0,5-0,8mm than weight could be even less than aluminum/ And, one more thing- aluminum is not very easy to weld and it oxidizes over time on fresh air.

 

[Archived-1]

Not much need for welding really with this mod, but my mig will do ally if i wanted to weld anything, i wont be using inox Rimants no need, ally wont rust and good grade will last just as long as grade 2 inox

 

[Archived-1]

I have just weighed my standard 1.8 arms.

 

[Riverblue]

Is that you in your avatar picture, Martin? . . . . Your arms don't look 1.8m long!!!

 

[RimaNTSS]

OK, OK, I am not arguing. Any solution, if made properly is good, aluminum or (edited) INOX. Perhaps I was little wrong about thickness of the pipes for feedarms, 1-1,5mm would be more proper.

 

[Archived-1]

Is that you in your avatar picture, Martin? . . . . Your arms don't look 1.8m long!!!

No Andy i am 6/1 and like a stick lol.

OK, OK, I am not arguing. Any solution, if made properly is good, aluminum of INOX. Perhaps I was little wrong about thickness of the pipes for feedarms, 1-1,5mm would be more proper.

No arguments rimants only discussion . its up to you what you use pal , i was just wanting to keep the weight down and saying i don't feel the need for inox here, by all means i am sure it will work just as well as ally .

 

[Captain Jack]

I guess with the CM being fibre glass, weighty arms shouldn't distort the dish surface (like they do on my 1.5m Gibby).

 

[Archived-1]

IMHO, to do this mod correctly work needs doing at the rear of the dish, i will be doing something like this.

 

[jase1]

I've painted some LNB holders last night. And painted they look like made of....... you will not believe!..... not polished INOX!
So, there is my plan: Next Sunday (can not do it on Saturday, as I go drinking fishing to the North sea) will take down Fibo 120 from my balcony and instead of it will erect CM 120.

I fancy having a go at making one of these for my 1.2 CM. Can you post some dimensions of it?

 

[Captain Jack]

Martin, your arm design is very similar to the one Laminas have in their 1.8m dish. Would be interested in seeing the final product (if you ever get that dish up in the first place!)

 

[Archived-1]

Martin, your arm design is very similar to the one Laminas have in their 1.8m dish. Would be interested in seeing the final product

The bottom arm needs beefing up with good support, and the little arms just act as stabilisers, basically just coping the Laminas/CM TX design

if you ever get that dish up in the first place!)

Thanks Alex for the , i will try and finish the levelling system tomorrow. then only the mount left to do for the time being,

 

[RimaNTSS]

Can you post some dimensions of it?

I did not make drawing before making. so now did one for you. Blue metal plate ~50x25mm about 5mm thick, pinkish metal plates 2mm thick 3 pieces 50mmX15mm and one piece 20x15 mm. Red solid lines where is welding took place. Green doted line- where is some bending applied. This was my last holder (not pretending to be perfect), I came to it after 4 trial versions, which are also workable solutions, I mean they can hold LNB in proper position and also allow some adjustments.

 

[RimaNTSS]

Couple of weeks ago I was at Wim's place. So we made LNB support for CM1,2m, it was just for tests, but, I think it is more than possible to make only one feedarm without any back supporting arms at all. So, main mirror stays unattached and therefore will not be affected by weight of feedarms.
In fact, I've seen somewhere picture of Prodelin 1,8m dish where only bottom feedarm was used.

 

[jase1]

I did not make drawing before making. so now did one for you. Blue metal plate ~50x25mm about 5mm thick, pinkish metal plates 2mm thick 3 pieces 50mmX15mm and one piece 20x15 mm. Red solid lines where is welding took place. Green doted line- where is some bending applied. This was my last holder (not pretending to be perfect), I came to it after 4 trial versions, which are also workable solutions, I mean they can hold LNB in proper position and also allow some adjustments.

Thank you very much for taking the time to do that.

Jason