Channel Master 1.8 Offset Stringing accuracy.

[John]

Was curious to see what the construction accuracy was of my 1.8 offset Channel Master so gave it a quick stringing. I ended up with a gap in the strings of approx 2mm. Would this be classed as acceptable / borderline ?.... Would be nice for other owners to have a quick string and share their results.

 

[RimaNTSS]

I was stringing Prodelin 1,8m, got no gap. Could you measure working area of your dish @John ? With the precision up to 1mm, and, if you can, also depth where threads are crossing with the precision up to 0,1mm.

 

[Archived-1]

Heavy lnd pull them out , I will be bracing mine if I decide to put something heavy on it, god knows what shape some metal dishes will be like .

Adjusting VSAT satellite dish distortion

Low transmit gain performance:
The performance of the dish may be substantially degraded if the weight of the radio assembly (Feed horn, OMT, ORU, BUC, LNB, etc) at the front causes the shape of the main reflector to be distorted.

At low and moderate elevation angles, the weight of the feed pulls the sides forwards.

 

[John]

@ RimaNTSS, I'll have to lower it down to do that. Very awkward and tricky whilst in up position, I ran out of playtime today . Will try and do that tomorrow.
That had crossed my mind Martin, the link is very useful matey. I'll look into that little mod tomorrow as well.;)

 

[Archived-1]

Turn buckles and strong wire was my first thoughts for an easy quick fix John, when I make the polar mount for the 1.8 I will make it so all the lnb weight is on the mount not the dish .

 

[zorbua]

Good job Martin I read this I was about to put this complete Tx/Rx assb on my 1.5 Dish...but now I am having second thoughts......heh heh
no seriously we had this problem with VSat - Prodelin 1.8 and 2.4 Dishes when we used heavy TX/RX equipment like the second image.

 

[Archived-1]

Good job Martin I read this I was about to put this complete Tx/Rx assb on my 1.5 Dish...but now I am having second thoughts......heh heh
no seriously we had this problem with VSat - Prodelin 1.8 and 2.4 Dishes when we used heavy TX/RX equipment like the second image.

Yes don't fit it zorbua, send it me for my dish , its only recently that ive had my 1.8 up and its only got a single lnb on it,

I have read about the problem in the past, this is the sort of thing I have in mind .
https://www.satellites.co.uk/forums/threads/channel-master-dish-arm-modifications.164288/

 

[zorbua]

But I think Martin just fitting a normal Lnb up to say a Kilo in weight on a CM won't effect the Parabola cause the arms can take such a weight without any
undue effect on the Dish. Mostly it's when TX/RX Heads are fitted that concern can be taken in consideration.

 

[Archived-1]

But I think Martin just fitting a normal Lnb up to say a Kilo in weight on a CM won't effect the Parabola cause the arms can take such a weight without any
undue effect on the Dish. Mostly it's when TX/RX Heads are fitted that concern can be taken in consideration.

Yes I would say your 100% correct, but in the future I might want to add extra lnb, for the little work it will take for me to implement this mod I can put what I want on the end of the arms with confidence .

 

[archive10]

But I think Martin just fitting a normal Lnb up to say a Kilo in weight on a CM won't effect the Parabola cause the arms can take such a weight without any
undue effect on the Dish. Mostly it's when TX/RX Heads are fitted that concern can be taken in consideration.

You are so right.
The Tier 3 dishes accommodate something like up to 15 kg of Rx/Tx gear.
Us Rx-people normally gross up to around 1 or 2 kg, with multi-LNBs and the holder.
Only the really ambitious people like @Trust1 with multi-LNB changers and what have you get anywhere nerar the Tx guys in terms of weight of electronics...

 

[zorbua]

Yes I would say your 100% correct, but in the future I might want to add extra lnb, for the little work it will take for me to implement this mod I can put what I want on the end of the arms with confidence .

Yes quite right no harm in making it more sturdy

 

[Archived-1]

Yes quite right no harm in making it more sturdy

Its only my time at the end of the day pal, it will be coming back down in the coming weeks and might be staying at low level, if I do the 1.5 will go in its old place.

 

[scopus]

Strung my Channel Master 1.8, strings touch nicely where they cross.

 

[John]

Strung my Channel Master 1.8, strings touch nicely where they cross.View attachment 86995 View attachment 86996 View attachment 86997 View attachment 86998

Cheers for that 'maboy .... she's down on the deck at the moment so going to see if i can see where this 2mm gaps coming from and measure the dish depth etc

 

[scopus]

Cheers for that 'maboy .... she's down on the deck at the moment so going to see if i can see where this 2mm gaps coming from and measure the dish depth etc

That's a big 10-4 John Boy.
I wonder if they have changed the mould, can I see a some sort of circular pattern in the middle of your dish John?
I have not got that.

 

[John]

That's a big 10-4 John Boy.
I wonder if they have changed the mould, can I see a some sort of circular pattern in the middle of your dish John?
I have not got that.

... It's a Johnny Mould Chris , all it is, is a pencil circle around the dot.... the dot in the middle is the landing spot when looking up the bore sight from the original CM feedholder. The circle helps me with Cband barrel alignment and any other strapped on lnb that might be there. Just in the middle of doing my right hand rear brace.

 

[scopus]

... It's a Johnny Mould Chris , all it is, is a pencil circle around the dot.... the dot in the middle is the landing spot when looking up the bore sight from the original CM feedholder. The circle helps me with Cband barrel alignment and any other strapped on lnb that might be there. Just in the middle of doing my right hand rear brace.

Ahh, Roger.....

 

[John]

Cobbled this right hand side brace up out of scrap bits and bobs in the workshop ... cost me nowt to do.
Although when you get up close to the CM ribbing you tend to think "nah, this will never warp" .... but iv'e a feeling, now that iv'e done one side brace and the other to follow , that this will be a benefit to the dish.
It just takes that little bit of stress out of the area around the side arm fixing point.

 

[Archived-1]

Nice work John, i like the mount did you make it pal ?.

 

[John]

Nice work John, i like the mount did you make it pal ?.

Yes matey, managed to cobble that up for next to nowt as well ...
When i bought my Precision 2.2 mtr you had to have one of their mounting kits as part of the deal. The cheapest option was their "A" Frame which consisted of loads of thick walled box section / large angle iron sections and that black rear frame you can see on the 1.8CM. None of it never got used and was in the back of the garage for years and years. Surprisingly the rear frame was an exact fit on the CM and is built like a brick sh.. house and the rest of the Precision stuff went on to make the new mount for the 1.8. To be truthful , i don't think i would trust another H-H motor mount again on any decent sized dish .... these 36" & 24" actuators are far more substantial but dont look as neat lol. The only outlay was for some 25mm oilite bushes , A2 & A4 nuts and bolts etc and some 3.2mm welding rods