@kinsmen2004
He want to stay ahead of the chart we dey pull am

OKA RE O , SO TI GBO. !
DIDN'T HEAR FROM YOU AGAIN. HW FAR ?

@Geometry and all dish fabrication experts,
After finding the focal point of your dish,should it fall exactly infront of the waveguide of the lnb at point A below, exactly in the middle of the waveguide at B or at the tip of the lnb at C for maximum signal acquisition to be realized?

Regards to all in the pursuit of knowledge.

@swordswifter

It is best at [A],
u cannot believe it, the ntwk just messed up my write up, the details of what happens at each position. i have to leave for somewhere right now, maybe, when i'm back.
see you guys.

geometry:

@swordswifter

It is best at [A],
u cannot believe it, the ntwk just messed up my write up, the details of what happens at each position. i have to leave for somewhere right now, maybe, when i'm back.
see you guys.

@Geometry,
I'll be looking forward to that my brother.Thanks!

Am learning somethng here.I am going to try constructing a 4m dish soon.

Easier said than done!

@ swordswifter,

Let us see what happens at the labelled position A, B and C respectively.

@ A;
The [A] is recommended by most designers, but in theory, the measurement of focal length
is to the PROBES.{two silvery or golden appendages emanating from the wall of the wave guard when
you look into the LNB from [A]}.one very important reason for A as location for focal point is due to
imperfection as a result of human error during mold making and satellite DISH fabrication. so not all
signal rays are specifically brought to focus, another reason is the fact that signal rays coming from
transponders are not absolutely parallel. hence there are bond to be some slightly off-focus converged rays.
so we need the space between A AND B, usually cylindrical or rectangular, to convey these rays to the probes
at B.Note that the oncoming electromagnetic waves from space is mechanical in nature and after convergence
are set to oscillate the probes.

@ B;
This is apparent location of the probes, but before B, let's see what happens between A and B: Here,
the slightly unfocused rays are collected and redirected, through constant reflection as they bounce
against the wall.[wave guard], this process contributes to the overall gain instead of just escaping the focus.
We can now visualize the reason for a need to have a receiving area bigger than a DOT as theory would imply.
Now at B, the collected electromagnetic waves set the probes into RESONANCE, and this message is transferred to
the electronic circuit connected to the probes, the circuit ,in turn, converts the received message to an
electrical impulse, in form of current in milliampes.(mA).

@ c;
This is the gateway to the processed signal to the the decoder in form of electric current in a very low
amperage.your decoder then interprets this to what you see as signal strength and quality.and consequently,
pictures and sounds.

CONCUSSION;
*Point A remains the best in practice.
*Point B only exist as supposed location for focus,but not accepted in practice because of human errors
that are abound during mold making and dish fabrication.

***HINT;
when you cut your LNB,one of what you intend doing is bringing your probes CLOSER to the focus,
BUT DON'T QUOTE ME ON MY LAST STATEMENT, IT IS WHAT I THOUGHT IT SHOULD BE. but i'm sure.

@ Ilish,
hey, why not try from smaller and latter proceed to bigger, say, 1.2m or 1.5m, reason being that if there were mistakes you would have courage to try
next time.

@ Eltonluigi,
There is no arm in trying new things sometimes. you know !?

@ all

Am all for the pix still what does the rest of the house think.

I think due to swords question geometry has move from stage one to ten.

Anybody agree.

good evening sword

@geometry, thanks for all ur efforts making this forum interesting.

I have seen a concrete mold of a sat dish in front of a shop & by my estimate, its size shld be 2.5M. it is well caved out with cement dat i believed the person used a real dish to create the mold.

My questions are:
1)Will one require a real dish sample to create a mold?

2)if yes, does it mean, each time one has to fabricate a particular size, one will need a sample from elsewhere to create the mold?

3)if No, what's the way out to fabricating several sizes without necessarily looking a a real sample to create a mold?

Tanx.

@Geometry,
Thanks for all your assistance.I'll take note of your caution too.Will do a bit more research and make the best of decisions from all that i learn.Thank you.

dodos:

@ all

Am all for the pix still what does the rest of the house think.

I think due to swords question geometry has move from stage one to ten.

Anybody agree.

good evening sword

@Dodos,
You are right but i believe you'll be one of the few people who will understand when I'm finally through with what I'm working on at the moment.The question i asked was also as a result of another satmate wanting to know the length of the focal point for his fiber dish.I'm satisfied with the responds so right now I'm going to sit back so that Geometry can continue with the class.Excuse me for jumping the gun.Geometry,the floor is yours.

i need a 3m fiber dish anyone?? 08051355133

@Life 707,

1] you don't need a real dish to create a mold in actual sense of it, but if you interested in pirating a dish, ba wahala ! we can go through that latter. but you need to be sure the dish you are copying is exceptionally perfect. also , don't expect too much from your pirated product. alas!

2] a successful mold fabrication can give you 1MILLION copies of dish from it.so , is not every time that you will need to make a new mold.

3] As for how to make mold, just follow the sequence the proceedings on this forum, and ask questions that are peculiar to your stages in the process.
remember you are always welcome.

swordswifter:

@Dodos,
You are right but i believe you'll be one of the few people who will understand when I'm finally through with what I'm working on at the moment.The question i asked was also as a result of another satmate wanting to know the length of the focal point for his fiber dish.I'm satisfied with the responds so right now I'm going to sit back so that Geometry can continue with the class.Excuse me for jumping the gun.Geometry,the floor is yours.

Thanks sword. I remember someone asked you to help with that problem. All the same thanks for the invite. I cant wait to see your project when it is done.

Nice day

@ Dodos,

plz, forgive me, right now we can only come up with a group of clumsily arranged pix, that might cause more of confusion than clarifications.
at what level are you in theoretical analysis of what size you are willing to experiment upon? if any, plz , let me know.

@ twinskenny,
your location ,plz. is it meant for motorization?

@ all'

microgi@nt has given us a very handy tool, software, the "PARABOLA" calculator, try and download it and fix your values . it serve as a mini simulator to some extent. i have used it it works very ,very well. anybody can try it.
THANK YOU Microgi@nt. http://www.files.com/file/4dd0ec433c179/Parabola.cab

geometry:

@ twinskenny,
your location ,plz. is it meant for motorization?

location is very close to Mowe in ogun state, yes it meant for motorization but i got all the accessories sir.

@geometry,
Thanks for the clarification, i will be patient to follow the tutorials.

@ twinskenny.
for a properly configured neck for smooth motorization, 3m, fiber dish, 08033926638.
people complain about the cost, but no one ever regretted. that is a warning though.!

geometry:

@ Dodos,

plz, forgive me, right now we can only come up with a group of clumsily arranged pix, that might cause more of confusion than clarifications.
at what level are you in theoretical analysis of what size you are willing to experiment upon? if any, plz , let me know.

@ geometry

First of all thanks for keeping the thread alive. Dont worry about the pix then. Please take your time to organize them properly. You see my problem might be fundamental. (i dont know if any GH member has the same opinion). First of all i cant seem to find the materials in GH. (any GH member who knows where to get these materials should please come to my aid.) Am alight with the calculations so far. Now my greatest worry is producing that mould. For me Nilesat is my target now so am looking at 3m or 2.4m at least.

Hope this helps.

swordswifter:

@Geometry and all dish fabrication experts,
After finding the focal point of your dish,should it fall exactly infront of the waveguide of the lnb at point A below

@swordswifter.The point[b] A[/b] should be at the phase centre of the feedhorn further back inside the horn.Most manufacturers recommend a distance of 1/4 inch from the LNB cover.

HELLO GUYS,
I HAVE A 3.2M (320 CM) DISH, BUT I DON'T HAVE THE FEED HORN ROD TO USE WITH IT.
PLZ I NEED ALL MEMBERS TO GIVE ME THE CALCULATION TO USE FOR ME TO DETERMINE THE SIZE OF FEED HORN ROD TO USE ON IT.

blexxonmak:

@swordswifter.The point[b] A[/b] should be at the phase centre of the feedhorn further back inside the horn.Most manufacturers recommend a distance of 1/4 inch from the LNB cover.

@blexxonmark,
Do you mean it should fall about 1/2 way between point A and B inside the lnb itself in my earlier illustration or about the same distance before i get to point A in the same illustration(coming from the center of the dish that is)?Thanks.

Hi everyone,
Whiles i'm waiting for blexxonmak to clarify himself,this is what I've found out.In finding your focal length,the shorter your "d",the longer your "F".I'm facing this problem right this moment.I intend fixing that tomorrow.I have a question,where can i find small hallow round(circular) pipes(metallic and very rigid ofcouse)to buy in Ghana?The medium sized iron rods are too heavy and the small sizes bend when their lengths exceed a certain distance.This post need urgent reply because i'll have to buy that tomorrow in order for my project to be at a level of between 80% and 90%.Thanks!

@Newtonn,
The calculations are quite simple.I'll post a typical example well worked out for you to follow with yours but for time be a little patient with me.My own project is taking too much of my time.Will get to you soon.
@Dodos,
If you are free today,you can join us on the Ghana Telecom university Campus-Tesano(Main Campus).I may need your input on one or two things concerning the project.When you get there,call this number-0200393956.Tell the fellow their group leader said you should meet them to help them with the Project work.He will bring you to me.See you soon.

@ newtonn,
get your dish depth (x) & i will give u ur tripod length. I will some sketching and post when i get back home. I have being away 4rm my system 4 d past few days. Though, its not complex.

@ newtoon,

remember pythagoras theorem ?
consider the two diagrams ; i.e theory and actual. stick to the theory. it gives you the actual tripod length with just little adjustment to actual focal length of your parabola [dish].
pytagoras states that; the square of the longest side (h^2 ) of a triangle is equal to the sum of the squares of the rest two sides
( a^2 + b^2 ) . i.e h^ = a^2 + b^2
in the case of the represented diagram ,

h = t,
a = line CB,
c = line AB
FOR CLARITY SAKE, in the actual diagram, there is a value for s , which is the radius of the scalar ring. the same value goes for ku- band lnb holder as indicated in the diagram.
by using my vernier calipers i got scalar ring diameter to be 16.5cm i.e the radius comes to 8.25cm which is (s)
hence; (a) = line CB = radius of the dish - s . i.e [DIAMETER/2] - 8.25CM.
(C) = line AB = focal length - x. i.e f - DEPTH, = f - x,

don't forget x represents how deep your dish is.

Newtonn, do you see why u need to measure your dish depth ?

@ Newtonn,
your dish looks like its from a good mould, try and protect it from damage by allowing it collect rain water., just turn it upside down. goodluck.
again your tripod length is (t) actual.
if any other things , feel free to ask.

@ all,
plz, point of correction , where i wrote stick to theory i meant 'actual' ,and my equation, instead of h^ it is h^2,
i.e, h^2 = a^2 + b^2
in statement ; square of hypotenous = the sum of the squares of the rest two sides