easy guide to calcullate the focal point of the off-set dish....

georgekamal

Regular Member
Messages
63
Likes
0
#1
dear friends and experts ,please guide me in following matter, is that 'how to
calcullate the focal point of the off-set dish? and i need step by step easy
guide..........b cause i'm very new and help less for this matter.

thankx for any help- regards-george
 

Channel Hopper

Suffering fools, so you don't have to.
Staff member
Messages
25,160
Likes
5,609
My Satellite Setup
A little less analogue, and a lot more crap.
My Location
UK South
#2
There isn't one.

Sorry
 
Messages
8
Likes
0
My Satellite Setup
Technomate 5500DACPI, Lemon 80cm Mesh, Moteck 2100SG Lemon 0.2LNB..
My Location
Berkshire
#3
I've heard many times that this is impossible. But surely if you coat the dish with aluminum silver car paint or coat it in tin foil it will reflect light to a focus point which you can find on a sunny day with a bit of paper and experimentation??? (As its an offset dish I assume you'll have some idea where the LNB should be already.)

As the dish is a reflector it will work the same for both light and radio waves of the size used in Satellite. I've heard stories about shiny transparent dishes burning out LNBs for this very same reason.

Obviously before using it for real, you'll need to un-silver the dish.... or cook your LNB. Good luck!
 
J

Jeff_19341

Guest
#4
The same can be achieved by sticking half a dozen of the small mirror tiles to the dish surface, so I have been led to understand.
 

2cvbloke

Bulbs need shelter too...
Messages
9,430
Likes
1,707
My Satellite Setup
No satellite stuff for the moment (aside from a 43cm minidish that was on the house already), Samsung SyncMaster T27B550 Smart TV & Monitor, and a few computers...
My Location
Near Pontop Pike, Co. Durham
#5
Jeff_19341 said:
The same can be achieved by sticking half a dozen of the small mirror tiles to the dish surface, so I have been led to understand.
Have to be careful doing that, I've seen parabolic mirrors setting fire to stuff after reflecting sunlight... :D
 

rolfw

Believe it when I see it Admin.
Staff member
Messages
37,698
Likes
1,286
My Satellite Setup
Technomate 5402 HD M2 Ci, DM7000s, Transparent 80cm Dish, Moteck SG2100 DiseqC motor, lots of legacy gear. Meters: Satlook Digital NIT, Promax HD Ranger+ spectrum analyser.
My Location
Berkshire
#6
Yes, I've heard it's a dangerous thing to do, my mate had a real problem. :)
 

Attachments

J

Jeff_19341

Guest
#7
One presumes that the operative has enough sense to remove the small mirror tiles (approx 1 inch square) after they have found the focal point of their dish

PS Rolf, no image on your above post.
 

rolfw

Believe it when I see it Admin.
Staff member
Messages
37,698
Likes
1,286
My Satellite Setup
Technomate 5402 HD M2 Ci, DM7000s, Transparent 80cm Dish, Moteck SG2100 DiseqC motor, lots of legacy gear. Meters: Satlook Digital NIT, Promax HD Ranger+ spectrum analyser.
My Location
Berkshire
#8
Whoops, tended to lose the impact. ;)
 

2cvbloke

Bulbs need shelter too...
Messages
9,430
Likes
1,707
My Satellite Setup
No satellite stuff for the moment (aside from a 43cm minidish that was on the house already), Samsung SyncMaster T27B550 Smart TV & Monitor, and a few computers...
My Location
Near Pontop Pike, Co. Durham
#10
Jeff_19341 said:
That's a bit drastic:(
It's just a joke!!! I'm sure anyone with a string of intelligence would use a lightbulb... :D
 
Top