Raven Gemini 90cm or Triax 88cm for 13, 19.2, 28.2 degrees E

spark

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#1
I want a dish with 3 LNBs to recieve 13, 19.2 and 28.2 degrees E near Sheffield. Should I go for a Raven Gemini 90cm or triax 88cm? Would the Raven be better because its elliptical?
 

rolfw

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#2
The Gemini is designed for multisat reception and has an offset bracket for that purpose, should do fine. :)
 

spark

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#3
Would the Visiosat 75cm BISAT be as good as the gemini? I prefer the looks!
 

rolfw

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#4
Not quite as good as the Gemini 90cm, but it is pretty close, as it is a real precision made dish, very impressed with the performance, not so much the price. :)
 

spark

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#5
thanks rolfw!

I've read a 70cm dish isn't suitable for my location for the 3 sats. From what I undersatand the 75cm Bisat has significantly more gain due to its shape and precision manufacturing. Is that right?
 

rolfw

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#6
It has better gain than some other 70cm dishes and probably better on the offset satellites than a standard single sat dish, but whether it can compare with even a a medium quality 90cm also designed to receive offset satellites is another thing. :)
 

spark

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#7
I'm not sure how to understand gain but I've found the gain for the visiosat at 11.3 Ghz to be 37.5dB and the raven to be 38.4dB. Is 0.9dB a large or small amount?
 

rolfw

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#8
For every few centimetres increase in size, you only add a point or so of db gain, so a 1 or 2 db difference is good.

I have fitted both the Visiosat 70cm and the Raven Gemini 70cm and the difference is not huge, slightly better on the Visiosat, but not good enough to compare with the 90cm Raven.
 
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#9
A gain difference of 0.9 dB doesn't sound like very much until you realise that gain in dB is a logarithmic scale. When you do a linear conversion it comes out as around a 23% increase in gain.

Phil
 

spark

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#10
Phil_S said:
A gain difference of 0.9 dB doesn't sound like very much until you realise that gain in dB is a logarithmic scale. When you do a linear conversion it comes out as around a 23% increase in gain.

Phil
23% more gain is quite a lot.

I think I'll go for the 90cm dish Raven. I don't want to set it up and find I can only get 40% or so signal and have to go through the process of a mail order return and refund.

Thanks to rolfw and Phil for helping me decide.
 

mhku

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#12
Same in Worcester on a clear 85 cm dish ;)
 
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