Made a start on my petal extensions ..

aceb said:
This one although the majority of sites I found while looking for the same information said the FP is just inside the throat of the LNB but only one site gave a distance, about 1/8". I never found a critical or theoretical distance so maybe it's not an exact science?

I've never had the enthusiasm to make the LNB/feed support adjustable other than packing it out on some washers so I'm not sure how much there is to gain from something that has been set up as above.
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Thanks Paul ..
Like you I never found definitive answers ..
And I have noticed some channels prefer the scalar feed backed off a little ..some prefer it placed further forward.
As you say ..not an exact science ..but a starting point for the theoretical must exist.
One of the reasons I made my tripod and feed as adjustable as possible ...to accomodate whatever flavour of theory I chose to follow ..and squeeze those pips.
We probably know through trial and error ..as much as anyone ..but I like to follow the science when I can.
cheers buddy
VS
 
VS, your focal length is not going to change by adding panels, only you f/d. If you have redone the maths and it appears the focal length has changed that means your panels have not followed the parabolic curve. As a ballpark figure you want to get the edge of your dish within 1/10th of a wavelength or better of where it should be if you want any hope of this working. 1 wavelength at 3GHz is 10cm so you want to aim to get the dish perimeter within 10mm of where it should be, and even better for performance to be good at higher frequencies (4.2 GHz).
 
Huevos said:
VS, your focal length is not going to change by adding panels, only you f/d. If you have redone the maths and it appears the focal length has changed that means your panels have not followed the parabolic curve. As a ballpark figure you want to get the edge of your dish within 1/10th of a wavelength or better of where it should be if you want any hope of this working. 1 wavelength at 3GHz is 10cm so you want to aim to get the dish perimeter within 10mm of where it should be, and even better for performance to be good at higher frequencies (4.2 GHz).
Click to expand...
Thanks Huevos ..
You have basically confirmed what I already knew ..
Tollerance of 1cm ..
Original focal length 80cm ..
With the additional wings ..currently 82cm ..so 2cm out in my positioning of the wings ..
If I can reduce the error to anything between 80cm and 81cm ..I will be happy ..
What about the other question I asked about the placement of the lnb and scalar plate relative to focal position ..
Is the the plate or the front of the lnb that is critical here ?
cheers mate
VS
 
Vipersan said:
Is the the plate or the front of the lnb that is critical here ?
cheers mate
VS
Click to expand...
I really don't know, only that the distance to the dish face should be identical to before you added the wings.
 
i kike to know did you meauysre 40cm on from underneath petal and up and whats your length, i want to extend my dish to 2.4m how do i go with it materials ,qauntities excetra i only seen the pics allready started what about how to measure intructions exetra thx nice thread
 
verwegsateliet said:
i kike to know did you meauysre 40cm on from underneath petal and up and whats your length, i want to extend my dish to 2.4m how do i go with it materials ,qauntities excetra i only seen the pics allready started what about how to measure intructions exetra thx nice thread
Click to expand...
Sorry m8 ..I can't give quatities as I just bought materials as needed ..
As to measurements ...there weren't any ...
If you read the thread from the begining it was explained in detail how I approached the problem ..
Basically I made a mold cast to emulate the last or outer portion of one petal ...
The using that mold cast from the original surface of the dish ..and made wider to follow the radial lines from the dish center spreading out to create wings which were the natural contnuation of 1 wing ....
I then used the single mold created to manufacture 6 _actual_ petal extensions in roving cloth fibreglass ...
Formed to give edges for structure and attachment ..to the main dish..
Structured ribs added to the non signal reflecting side to maintain shape ..
And each wing extension laminated with layers of fibreglass tissue ..and Aluminium sheet in the form of 4 inch wide radial adhesive strips ..
Final layet of gelcoat for weather protection..
Its all there in the thread ...the photos are simply to aid and inform..
the devil is in the detail.
sorry I can't give more information than I already provided ..and there is a lot of that if you read it thoroughly.
rgds
VS
 
...What can I say ..
raining miserable cold...with one day ...yesterday ...that was something like useable..
So worked my ass off to get the last 2 panels removed ..resined ...fibre glass tissued ..rubbed smooth ...adhesive aluminium strips applied ...spray primed ...gelcoated ..redrilled and today ..cold and wet ...got them back on Christina ..
The rain held off long enough to get the job done ..and a photo taken.
Flaming June ..more like Flaming Joke.
Anyway ..the wings still have to be removed again ..rubbed smooth again ..and finaly sprayed the correct colour as close as I can get..
..but that will have to wait until I build up some energy reserves ...and a warm dry day ...probably sometime later this Flaming Summer..
cest la vie ..
At least the panels should be weatherproof now ..and are working reasonably well..though maybe some more tweaking and adjusting in the final phase.
rgds
A very weary VS ..full of a cold ..and freezing my nutz off..
;)
 

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I can only echo your sentiments about this poxy weather, I managed to get the 1.2 up and getting signals from 66E-45W before the rain started and the temperature dropped even lower than it was at the start. The next chance to contine fine tuning it and remain dry hasn't yet appeared on the five day forecast.
 
Agree 100%, with the flaming June rant, I had so many plans, for this 4 day weekend, and most of them were washed away with the rain.
 
aceb said:
I can only echo your sentiments about this poxy weather, I managed to get the 1.2 up and getting signals from 66E-45W before the rain started and the temperature dropped even lower than it was at the start. The next chance to contine fine tuning it and remain dry hasn't yet appeared on the five day forecast.
Click to expand...

..thats why I rushed to complete it as far as it is Paul ..
No sign of any decent summer weather on the horizon ...and possible high winds coming ...so I wanted to ..not only get a full complement of stainless bolts anchoring the wings to the dish ...but lateral bolts to bind the wings to each other ..
Thus making it more rigid .
I guess its well on the way to complete now ...but approx 5 months of proper graft has taken its toll ..
I'm knackered..
Hope you get chance to work on your 1.2 soon..
cheers buddy
VS
 
Vipersan said:
No sign of any decent summer weather on the horizon
Click to expand...
Lovely and warm and sunny here, and has been ever since... hmm... last summer.
 
The sun came out today ...and scared the sh!t out of me in the process ..
its gone in again now ...but managed a small dry window of approx 2 hours ..so even though I feel rough and ache ..I dragged my carcass outside to rub down , spray and plastikote 2 wings ..
These 2 wings are now done and wont be removed again ...unless the weather has other ideas..
Not a perfect colour match ..but as close as I can get ..
What do you guys think ..?
The next picture I post will hopefully be the completed dish/wing set..
Personally I think Christina will look beautiful in her new clothes...
;)
rgds
VS

..just looked out the window ..and some ominous looking black cloud accumulating ...
Time to down tools me-thinks
 

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I bow to you, VS. An amazing achievement - sort of like those guys in a shed making a supercar!

Would you like to make some wings for a Penta 85 dish? :)

Also, if you want a perfect colour match, why don't you paint the whole dish?
 
Captain Jack said:
I bow to you, VS. An amazing achievement - sort of like those guys in a shed making a supercar!

Would you like to make some wings for a Penta 85 dish? :)

Also, if you want a perfect colour match, why don't you paint the whole dish?
Click to expand...

Thanks for the compliments guys..
As to the colour match ..
Close enough is good enough ..I personally liked the outer rim silver ..but this would have drawn unwanted attention ..so providing it blends in well enough ..then it will suffice.
Sorry CJ ..I realise you're just joking ..but...one set of wings is enough ..
They don't and never will justify the cost of producing ..both in monetary terms ..nor physical wear and tear on my 54 year old MS riddled carcass.
This has been a labour of love on my part ..and one I don't have any intentions of repeating.
The mold however can be re-used if anyone with a similar dish wants to borrow it ..
I would only ask they return it intact ...just in case the weather gods decide to have some fun with Christina.
I'm happy with the results ..and certainly the increases in signal gain I've seen have justified the months that went into the project..
Not perfect and I'm sure there was more to be had ..but not bad for a home build in a back yard...battling the weather.
;)
cheers
VS
 
Yes very well done, a labor of love fully understood.

A quick question (you may have answered it before.) Did you calculate the compound angles of simply blend the extensions into the profile of the existing dish?
 
VS, was this Nelson_b's dish originally? Just saw some pictures of his "old" dish which is the same as yours...
 
@HDP ..no calculations involved other than to increase the effective radius segment size for the extended wing ...and this too was more or less a guesstimation.
Roughly 1 + 1/3 of a wing involved in making the cast.
A cast of the last 9 inches of an existing wing was used as a template for the mold..

@CJ ..No ..Ive had Christina for approx 20 years
Nelson still has his Alcoa which is in daily use for digital radio reception in ku from the East I believe..
rgds
VS
 
Very nice! Impressed that you get Eastern beam on Turksat - didn't think it was possible in the UK.
 
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