Prime focus feed 0.55 f/d

bodge

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#1
Does anyone know where I can get hold of a Prime focus feed with a f/d of 0.55 ? I have a very shallow 2 metre dish and need this high figure to maximize the signal. Most prime focus feeds are in the region of 0.34 to 0.42. The only one I have found so far costs $350 - a little too expensive !
 

steffo78

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28E 19E on 120cm Gibertini homemade sidemount with Gibertini feedhorn, Inverto C120. 5E 1W on 85cm triax. Digiality VC-CI 204 and Triax dvb-65s receivers. Matrix-cam not working. Swedish Canaldigital "local", Norwegian Viasat.
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#2

steffo78

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28E 19E on 120cm Gibertini homemade sidemount with Gibertini feedhorn, Inverto C120. 5E 1W on 85cm triax. Digiality VC-CI 204 and Triax dvb-65s receivers. Matrix-cam not working. Swedish Canaldigital "local", Norwegian Viasat.
My Location
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#4
The feedhorn has a f/d of 0.55 and that means it also has a certain opening-angle.
If you feed from a offset or primefocus does not matter as long as the dish has a round shape when looking from the focalpoint. (offset appear to be round when looking fron feed point)
If it fits is another question but I guess you can make it fit anyway.

Maybe there is another horn better suited, what make is the dish?
 

bodge

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#5
steffo78 said:
The feedhorn has a f/d of 0.55 and that means it also has a certain opening-angle.
If you feed from a offset or primefocus does not matter as long as the dish has a round shape when looking from the focalpoint. (offset appear to be round when looking fron feed point)
If it fits is another question but I guess you can make it fit anyway.

Maybe there is another horn better suited, what make is the dish?
The dish has Nokia and Luxor written on it but thats about all I know.The seller told me it was a prototype. This may explain why it is so shallow. I attach a picture ( I have since removed the old C band feed )
 

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steffo78

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My Satellite Setup
28E 19E on 120cm Gibertini homemade sidemount with Gibertini feedhorn, Inverto C120. 5E 1W on 85cm triax. Digiality VC-CI 204 and Triax dvb-65s receivers. Matrix-cam not working. Swedish Canaldigital "local", Norwegian Viasat.
My Location
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#6
Maybe someone else is more familiar with this dish and a suitable feed.

If you are in Sweden and want to try the Smw-horn you can order cheap from Hansa-electronic.com
 

bodge

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#7
steffo78 said:
Maybe someone else is more familiar with this dish and a suitable feed.

If you are in Sweden and want to try the Smw-horn you can order cheap from Hansa-electronic.com

Is this the smw horn on this page ?

_http://www.hansa-electronic.com/tillbehor.asp
 

steffo78

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My Satellite Setup
28E 19E on 120cm Gibertini homemade sidemount with Gibertini feedhorn, Inverto C120. 5E 1W on 85cm triax. Digiality VC-CI 204 and Triax dvb-65s receivers. Matrix-cam not working. Swedish Canaldigital "local", Norwegian Viasat.
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#8
Yes thats the one.
But check that it really is SMW, I thought it said SMW but it does not now.
At least the horn on the picture should be a SMW xm-601.
The text says integrated feedhorn and ferotor so im not sure.
 

bodge

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#9
steffo78 said:
Yes thats the one.
But check that it really is SMW, I thought it said SMW but it does not now.
At least the horn on the picture should be a SMW xm-601.
The text says integrated feedhorn and ferotor so im not sure.
I've written to Hansa to find out-the price of 90 crowns is certainly a lot cheaper than the 400 crowns + that smw want for this feed
 

steffo78

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My Satellite Setup
28E 19E on 120cm Gibertini homemade sidemount with Gibertini feedhorn, Inverto C120. 5E 1W on 85cm triax. Digiality VC-CI 204 and Triax dvb-65s receivers. Matrix-cam not working. Swedish Canaldigital "local", Norwegian Viasat.
My Location
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#10
Also at parabolic.se 25kr they are selling out different horns if you go to amatörradio and utförsäljning. I have been looking for horns myself, coming back to me now.
 

Likvid

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#11
It will be hard for you to find a suitable feed to your dish as there are not more than a few feedhorn manufacturers in the world and most feeds are a compromise to adjust to a range of different f/d's. like 0.5-0.65

Seavey is the only one that produce feeds for specific f/d's

I read on the Invacom site that their integrated feed on their LNB starts at f/d 0.5

Have you tried the Invacom with your dish?

I beleive your dish was meant for VSAT purposes as they have high f/d's.

Best thing would be to ditch the dish and buy a dish that works to standards or be happy with what you get now.
 

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#12
Likvid said:
I beleive your dish was meant for VSAT purposes as they have high f/d's.

From the picture I doubt very much that Bodge has a VSAT prototype.

Also I doubt the dish is actually 0.55 f/d from first impression, however stranger things have been made.

If it was originally a C band dish then the upgrade to Ku band may show it is not worth playing with.
 

bodge

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#13
Likvid said:
It will be hard for you to find a suitable feed to your dish as there are not more than a few feedhorn manufacturers in the world and most feeds are a compromise to adjust to a range of different f/d's. like 0.5-0.65

Seavey is the only one that produce feeds for specific f/d's

I read on the Invacom site that their integrated feed on their LNB starts at f/d 0.5

Have you tried the Invacom with your dish?

I beleive your dish was meant for VSAT purposes as they have high f/d's.

Best thing would be to ditch the dish and buy a dish that works to standards or be happy with what you get now.
But if my calculation of 0.55 is correct ( which I am sure it is ) presumably a 0.5 to 0.65 feed will give a better result than the 0.3 to 0.42 I am using. The question is how much of a better result ?
 

steffo78

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My Satellite Setup
28E 19E on 120cm Gibertini homemade sidemount with Gibertini feedhorn, Inverto C120. 5E 1W on 85cm triax. Digiality VC-CI 204 and Triax dvb-65s receivers. Matrix-cam not working. Swedish Canaldigital "local", Norwegian Viasat.
My Location
Sweden/Norway,Telemark
#14
Why dont you take a universal LNB and make a test? f/d around 0.6 usually
Adjust up and down until you get maximum signal strength.
I guess it would give better results than a feedhorn with f/d 0.4, gives you an indication in the right direction.
It is a little confusing but as I have understood it a feedhorn has a f/d value where it is peaking but you can also use it around that value.
Then the focalpoint can be at different spots inside the feedhorn, within a range for example 0.5-0.7 , this is at least my conclusion, please correct me if I am wrong.
If you have a dish with f/d 0.55 and use a horn with f/d 0.6 you must move the horn a little bit out compared to using a "perfect" feedhorn.

Go to satellite-calculations.com and calculate the opening angle for different f/d values.
 

Likvid

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#15
bodge said:
But if my calculation of 0.55 is correct ( which I am sure it is ) presumably a 0.5 to 0.65 feed will give a better result than the 0.3 to 0.42 I am using. The question is how much of a better result ?
As you already told me before you have done the correct measurements and i don't doubt that you got a f/d of 0.55

I can't recommend anything right now as it's all down to trial and errors.

Invacoms site says:

Invacom LNBs with integrated feed horns are designed for dishes with an F/D of 0.55 - 0.65.

Try and see if it performs better than your current feed.
 

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#16
If its of any help a dish with f/d of 0.55 would require a feed with aperture of about 110 degrees. Most scalar feeds will work to about 120 degrees.
 

steffo78

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My Satellite Setup
28E 19E on 120cm Gibertini homemade sidemount with Gibertini feedhorn, Inverto C120. 5E 1W on 85cm triax. Digiality VC-CI 204 and Triax dvb-65s receivers. Matrix-cam not working. Swedish Canaldigital "local", Norwegian Viasat.
My Location
Sweden/Norway,Telemark
#17
Did you ever get it working?
Just curious...
 
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