Channel master 180 dish installation project

[RustySpoons]

Yes for me as well......the twin is very sensitive......not tested myself but comments are plentiful that it outperforms the quad!

I put a post on here a while back, although not scientific I tested all 3... In terms of performance for me I rank them:

1st IBU Twin
2nd IBU Single
3rd IBU Quad

 

[dishdx]

If the mesh is realy stainless (probably yes, the demage looks like older), i will do with it nothing (only the frozen watter in the mesh could be problem). It is relative small area, not visible at first look, i noticed it when i the dish washed up.

Any repairs are unlikely to improve the performance or longevity of the dish.
My impression is that the steel mesh is stainless, so no further damage done.
But you might want to fix it for aesthetic reasons.
You can use resin-like filler in the form of a car-body repair kit (eg from your local Halford's) to fill in any cavities.
Then sand down, and paint the area.
Or just paint the area to seal it from further deterioration.

 

[dishdx]

Today i wrote to one well known satellite store specialised on big dishes, and result is, that i can use my original 6 holes feedhorn + 8 holes C120 LNB. 4 holes of the 8 should has the same position. So 4 screw is enought. I will buy C120 Flange Inovacom or Inverto Red LNB, i will see if it will be ok. If not, i will drill new holes to feedhorn flange.

 

[RimaNTSS]

i can use my original 6 holes feedhorn + 8 holes C120 LNB. 4 holes of the 8 should has the same position.

Is that what specialists told you?! I must say, they are wrong. There will be only 2 holes at the same position, not 4. But also 2 might be enough.

 

[archive10]

Is that what specialists told you?! I must say, they are wrong. There will be only 2 holes at the same position, not 4. But also 2 might be enough.

Yes, there is some maths here that doesn't quite work.
6 holes: 60 degree spacing. 8 holes: 45 degree spacing. When does 45 and 60 add up? Only at 180 and 360. So only two holes...

I don't want to sound smug, but this forum has more specialist knowledge than most satellite stores...

 

[archive10]

Today i wrote to one well known satellite store specialised on big dishes, and result is, that i can use my original 6 holes feedhorn + 8 holes C120 LNB. 4 holes of the 8 should has the same position. So 4 screw is enought. I will buy C120 Flange Inovacom or Inverto Red LNB, i will see if it will be ok. If not, i will drill new holes to feedhorn flange.

...and don't take anything for granted.
I have SMW feedhorns with four holes. It would be quite obvious to think that these would fit an 8-hole LNB (assuming the diameter of the ring of holes is exactly the same on both feedhorn and LNB! Luckily, it is.)
However, SMW, for some obscure reason, decided to make the holes at different degree spacings. Thus the pattern made by the four holes are not a square, but only a rectangle. So no perfect match with C120 LNBs here either...

 

[archive10]

...and don't take anything for granted.
I have SMW feedhorns with four holes. It would be quite obvious to think that these would fit an 8-hole LNB (assuming the diameter of the ring of holes is exactly the same on both feedhorn and LNB! Luckily, it is.)
However, SMW, for some obscure reason, decided to make the holes at different degree spacings. Thus the pattern made by the four holes are not a square, but only a rectangle. So no perfect match with C120 LNBs here either...

And it gets worse.
More important then the number of attachment points between LNB and feedhorn is the bore of the waveguides in the two components.
The transition between two sections of the waveguide should be as smooth as possible.
(The different C and WR interfaces specify the waveguide size and shape.)
If you have, say, an abrupt transition between a 30 mm pipe and a 27 mm pipe, the "step" will make all sorts of re- and deflections, giving worse performance.
Luckily, the common 6-hole feedhorns seems to be C120-like (although I don't know if it's another Cx standard).
This means you can even (carefully) drill new hole in either feedhorn or LNB to make new holes to make more than two attachment points...

 

[dishdx]

st1 Thank you for very useful comment! 2 holes ok, 3rd i will drill. I would like to buy Inovacom SNF-031. On satellitesuperstore, they write, that this LNB is not good for long coaxial cable (i will have cca 45 m), i hope it will not be a problem like other standard LNB i have at home? Any opinion?

 

[4wd]

Got an Invacom twin on 90cm prime dish with 50m of cable (final install will be 20m), S & Q levels are excellent on several different receivers.

 

[dishdx]

Hi! The dish CM180 is on the place! :-) Pole is 114mm, concrete designed according Channel Master Instalation manual.

But i have one problem - feed support arms are probably originaly from 2,4 m dish (they are 1,7 m long), und i can´t use them without shortening them. Does anybody knows the right length of arms for my RX/TX version of LNB arm? It will be cca 1,5 m, when i adjust the position of main LNB arm to best signal.

The second option could be to place the long support arms to the end of main LNB arm without shortening (red lines)... see picture.

Thank you for help:-)

P.S. Flange LNB with original CM feedhorn i will install next weekend

 

[Channel Hopper]

Somewhere on the forum is a line diagram of the 183 series dish with dimensions. It might even be a full manual.

 

[RimaNTSS]

It will be cca 1,5 m, when i adjust the position of main LNB arm to best signal.

For clarity: you must adjust all the feedarms and LNB not to best signal but to best position of the LNB. And then, moving the dish horizontally and vertically get the best possible signal. Of course, do not forgetting to adjust skew of the LNB.
Make side-arms adjustable in length, then, for sure, you will be able to perfectly co-locate LNB's Phase center with antenna's Focal point.

 

[dishdx]

Thanks all for comments! But what is the best position? How can i find it? Now i use the dish without arms.

Jirka

For clarity: you must adjust all the feedarms and LNB not to best signal but to best position of the LNB. And then, moving the dish horizontally and vertically get the best possible signal. Of course, do not forgetting to adjust skew of the LNB.
Make side-arms adjustable in length, then, for sure, you will be able to perfectly co-locate LNB's Phase center with antenna's Focal point.

 

[RimaNTSS]

Did not you already see collage I made? Will duplicate it here as well. For 1.8m dish follow blue digits.