Dish illumination

**koansrc** · 06-11-2007

another silly question folks I'm afraid.

You know when we say "the feedhorn illuminates the dish" or vise versa ... well as I was fiddling with lnb in the dark with a torch I thought wouldn't it be great to be able to actually see how much of the dish is getting "illuminated" by the lnb !!

So in order to actually physically see this "illumination", would there be any point in attempting to actually shine light thru the feed and onto the dish ? Would be great fun to adjust the feed that way and then re-attach the lnb.

[ If this isn't a siily idea, then it's already copyrighted and patented

]

**Robbo71** · 06-11-2007

Originally Posted by koansrc

another silly question folks I'm afraid.

You know when we say "the feedhorn illuminates the dish" or vise versa ... well as I was fiddling with lnb in the dark with a torch I thought wouldn't it be great to be able to actually see how much of the dish is getting "illuminated" by the lnb !!

So in order to actually physically see this "illumination", would there be any point in attempting to actually shine light thru the feed and onto the dish ? Would be great fun to adjust the feed that way and then re-attach the lnb.

[ If this isn't a siily idea, then it's already copyrighted and patented ]

I think its a silly idea

because light is not going to behave the same way as microwaves do inside the feedhorn. Light needs something that is reflective to it, like a mirror or something shiny. The feedhorn on the other hand could be a matt surface and still work.

Although the idea is not totally stupid, as I have read in another post somewhere that lasers can be used to reflect off the dish surface ok, to check assembly of a petalised dish.

**koansrc** · 06-11-2007

ehm, funny thing is, this idea has got me thinking ... silly me ...
and I think that any light source coming thru the feed and onto the dish, will produce a circle of light on the dish. Could I use this circle of light to "center" the feedhorn and aim it ?

Another reason I like this idea is that it gives me an excuse to work on the dish at night too ...

***2cvbloke*** · 06-11-2007

How about hot-gluing 8 LEDs around the LNB? I dunno what it'd do technically, but it'd make your dish look cool...

**Robbo71** · 06-11-2007

You could also cover your dish with aluminium foil, point it at the sun, strap some sausages to the feedhorn and have youself a free barby.
and if you used red leds, it would look all the more inviting.

***2cvbloke*** · 06-11-2007

Originally Posted by Robbo71

You could also cover your dish with aluminium foil, point it at the sun, strap some sausages to the feedhorn and have youself a free barby.
and if you used red leds, it would look all the more inviting.

Mirrorball mirrors are better than tinfoil, don't you watch Mythbusters???

**Robbo71** · 06-11-2007

Originally Posted by 2cvbloke

Mirrorball mirrors are better than tinfoil, don't you watch Mythbusters???

No, but your'e right of course.

Also use multicoloured flashing LEDs and you could have yourself a Disco.

***2cvbloke*** · 06-11-2007

Originally Posted by Robbo71

No, but your'e right of course.

Also use multicoloured flashing LEDs and you could have yourself a Disco.

Very true, or a very unique Christmas decoration...

**aba** · 06-11-2007

sound like the old cb days if some one was useing power use to get i fluaresant tube and strap it to the side of there aerial ever time they went to transmit the fluaresant tube would start to glow should have seen them at night

***2cvbloke*** · 06-11-2007

Originally Posted by aba

sound like the old cb days if some one was useing power use to get i fluaresant tube and strap it to the side of there aerial ever time they went to transmit the fluaresant tube would start to glow should have seen them at night

I remember getting a zap from my old CB magmount aerial, I didn't mean to touch the aerial, I just brushed it whilst nattering and, erm, yes, I sent an expletive over the airwaves!!!!

***CROSSBONES*** · 06-11-2007

This may help you out Koansrc.

-http://gjullien.fr/mirrors/mirrors.htm

Any one for some steak?

-http://backya2.fatcow.com/j/solardsh.htm

**tesla** · 06-11-2007

I can't understand the purpose of this thread.

@koansrc re partida, gia kane to pio liana.

***2cvbloke*** · 06-11-2007

Originally Posted by tesla

I can't understand the purpose of this thread.

@koansrc re partida, gia kane to pio liana.

I think I kind of sent it off topic with the LED thing, so it doesn't make much sense now...

**Topper** · 06-11-2007

In that case I will consign it to the archives by closing the thread if you wish

**koansrc** · 07-11-2007

I musta hit a funny bone with everyone ....

**koansrc** · 07-11-2007

Originally Posted by tesla

I can't understand the purpose of this thread.

@koansrc re partida, gia kane to pio liana.

partida i patrida to idio einai ...

I was discussing another hi-tech, scientific way to check if the feedhorn is aimed at the center of the dish .... and then all humour broke loose !

I think it's off to the archives with this one ...

**tesla** · 07-11-2007

i suggest something else. Remove the off topic posts and let the thread continue.

@koansrc: you are right, i should write patrida. It was a little bit late when i wrote the post.

***CROSSBONES*** · 07-11-2007

This may help you out Koansrc.

-http://gjullien.fr/mirrors/mirrors.htm

Whats off topic about that?

**dig deep** · 07-11-2007

I vote for the 8 leds

It is soon X-mas so use red ones

**mhku** · 07-11-2007

koansrc and tesla:

Forum Rules

.. please post only in English (unless in one of the the international forums)..

***2cvbloke*** · 07-11-2007

Originally Posted by dig deep

I vote for the 8 leds

It is soon X-mas so use red ones

Red & Blue for me...

**koansrc** · 11-11-2007

Originally Posted by koansrc

So in order to actually physically see this "illumination", would there be any point in attempting to actually shine light thru the feed and onto the dish ? ]

Well folks I actually went ahead and tried it (it was a slow kinda Sunday). I think it works! Well sort of. I removed the lnb and left just the feedhorn attached to the dish. I then got a flash light and centered it on the back the feedhorn and guess what ... a nice circle of light appeared centered on the dish. It didn't show me how much of the dish is illuminated but it did show whether the feedhorn was centered.

**skull** · 11-11-2007

now u r using ur brain bro but even if the feed horn is not pointedtoward centre u can get a signal by moving the dish.

thnx

**koansrc** · 12-11-2007

Originally Posted by skull

now u r using ur brain bro but even if the feed horn is not pointedtoward centre u can get a signal by moving the dish.

thnx

I believe the point is to get it centered, so assuming the focal distance is correct, you are "illuminating" = using the entire surface of the dish. If it's off center, then your lnb will be looking over the edge on one side and not all the way to the edge on the other, which in my mind is less signal and more noise.

**koansrc** · 12-11-2007

Originally Posted by CROSSBONES

This may help you out Koansrc.

-http://gjullien.fr/mirrors/mirrors.htm

cheers crossbones, I think the mirror trick is one way to check the dish geometry and see if it's bouncing evrything back at the lnb and therefore checking if you've got the focal distance right. I think it should work and give some good indications if something is wrong
My problem ( and that's why i started this silly thread ) is that i now realize that it is very difficult to work with a 3m dish. I simply can't get to the upper half and tie strings and stick mirrors etc. , so I was looking for a way from working only from the lnb.

Now, about the LEDs and the colour scheme. How about a christmas tree light rope, all the way around the perimeter which will rapidly flash in all sorts of patterns and have it's own 4-note xmas carol player feeding of the 18v.

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