LNB skew vs DISH skew (1 Viewer)

Status
Please reply by conversation.

jenom

Thread Starter
SatelliteGuys Family
May 22, 2006
83
1
I have a small dish (around 22") which rotates.
Thinking of removing rotating parts and attach it to a larger (30") dish to make dish skewable.
I would like to know whether it is worth the effort, and I will end up with some gains compared to just skew the LNB on a same dish?
Thanks for all replies!
 

Anole

SatelliteGuys Master
Sep 22, 2005
11,819
10
L.A., Calif.
Round dishes you usually skew the LNBF.
Elliptical (oval) dishes, you usually skew the entire dish.

(there are exceptions, and they all have good reasons)

I'd call a 30" dish just minimal size for general Ku FTAing.
If it's round and you're going to set it up fixed-aimed, just skew the LNBF.
If you put it on a motor, the point is moot, 'cause the motor skews the entire assembly. - :up

What sort of dish are you going to use?
 

jenom

Thread Starter
SatelliteGuys Family
May 22, 2006
83
1
The dish I called round is a 21" wide, and 22" tall, has a Y shaped dual LNB holder and it has a canadian satellite provider logo printed on it.
I am thinking to take of the rotating mechanism and use it on a 30" qsat dish, which is already in use for fta, works fine for 30,72,89,97,101
My question is: do I gain anything (other than experience) by making the dish skewable ? (instead of skewing the LNB)
Thanks!
 

phlatwound

SatelliteGuys Pro
Lifetime Supporter
Dec 25, 2007
3,250
203
Goosapeak Junction
Sounds like your dish is a typical "round" offset dish. That shape is a section of a parabola, and your LNBF "sees" it as being truly round.

That being the case I will quote what Anole said previously (since he nailed it perfectly):

"If it's round and you're going to set it up fixed-aimed, just skew the LNBF.
If you put it on a motor, the point is moot, 'cause the motor skews the entire assembly. -
"

In a typical circumstance, no appreciable gain to be had by making your dish skewable. :)
 

Iceberg

The No Pain Train
Supporting Founder
Nov 17, 2003
282
35
None Your Business
wont work. The focal length on a Bell/Dish dish is different than a 30" dish (actually each size dish has a different focal length)
 

jenom

Thread Starter
SatelliteGuys Family
May 22, 2006
83
1
From the replies, I think I did not described the situation clearly:
I am planning to take of the rotating mechanism from an unused Bell dish
It has 2 parts: Part 1 is attached to the back of the dish with 4 bolts, Part2 is which goes to the pole.....and these two part a held together with 2 bolts only.
On the 30" dish, I will install a small rectangular metal plate adapter at the back, using the original 4 holes already on the dish. (I do not want to make new holes)
Then drill 2 holes the adapter plate to attach the original 30" dish's lnb arm to this adapter plate . (so the focal lenght will same as before)
Next drill 4 holes an the adapter plate and mount the Bell rotating mechanism to this adapter plate
Of course, I will need to cut of the lnb arm from the Bell part # 1 .

My theorical question is: Would I get any gain (dB) if I make a dish skewable , instead of skewing the LNB only ?

(PS: I wish I can make some pictures, but my digital camera just stopped working recently) )
 

Iceberg

The No Pain Train
Supporting Founder
Nov 17, 2003
282
35
None Your Business
ok now it makes sense ;)

you probably wont notice much difference on a stronger transponder but you might notice a few point gain on weaker feeds especially at the end of your arcs (the further away from true south)
 

jenom

Thread Starter
SatelliteGuys Family
May 22, 2006
83
1
sounds like it would not worth the effort [ lots of work, dish would get heavier (extra plate)]
Thanks for all the replies!
 
Status
Please reply by conversation.

Users who are viewing this thread

Users Who Are Viewing This Thread (Total: 0, Members: 0, Guests: 0)

Latest posts

Top