Raven 90cm dish

tavescan

Hi

I have very recently started to dabble with satellite TV, primarily to obtain Spanish TV as a means of helping my wife with her spanish studies. I installed a SKY 60cm Zone 2 dish with what I assume is a pretty standard LNB (WNC F18 single) and was very happy with the results from the Astra 1 series of satellites.

I decided to try for the Hispasat Satellite, but obtained very general advice that a 90cm dish would be needed. I didn't mind buying another dish as I was quite keen to experiment with different sizes of dish, so I opted for the Raven Gemini eliptical 90cm and a Skyware SX1019/S LNB, this being part of the recommended dish/LNB combination from a supplier. Apparently it seems to be important to have a LNB with an eliptical wave guide when using an eliptical dish. The /S indicates that the Skyware LNB has such a shape. (So I am told).

Just to get a feel for the dish and LNB I decide to firstly aim it at the Astra 1 satellite to compare the results with that obtained from my Sky dish. I fully expected to see an increase in signal strength due to the larger dish size.

However, much to my surprise (and disappointment), having set up the dish in exactly the same position as my original dish, and hence able to receive the Astra 1 satellite transmissions, the signal strength was actually between 5 and 10 dB less than my Sky dish was able to receive. The focus adjustment made hardly any difference to the signal strength, but I'm not sure if it should anyway. I assume that I adjusted for the correct LNB rotation on the basis of the quality level indicator on my receiver.

I do have experience in RF work, but I have hardly any experience with satellite TV installations, so I have a feeling that I'm missing something obvious here in doing this direct comparison. Any help would be appreciated. The measurements were carried out with a fairly old Spectrum Monitor utilizing the Astra analogue carriers as a means of comparing signal levels.

Len

rolfw

The Raven Gemini 90cm does not require a Sky eliptical feed LNB (which is what the /S designates), it is designed for a standard Circular feed LNB which will illuminate the dish face perfectly.

On the other hand, a 70cm Zone 2 minidish would be perfectly adequate for Hispasat. providing the skew on the LNB cand be adjusted to around 5 O'clock, rather than 7 O'clock for Astra 1 or 2, so the dish/LNB combination you have bought, should still do the job.

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tavescan

Thanks for the speedy reply Rolf. I did wonder about the LNB, but the fact that the supplier clearly stated (with quite extensive preamble) that the 90cm dish should have the eliptical LNB influenced me. I may well drop them a line indicating their mistake.

Len

rolfw

I use the Raven Gemini dishes, both 70 and 90cm versions with standard LNBs which fit the standard 40mm collar supplied with the dish. When Raven display the dishes, they always display with a standard LNB, the Horizontal elipse of the dish is designed so that the dish can pull in neigbouring satellites well with an offset LNB or LNBs.

What you might consider doing, is use the 90cm with the Eastern satellites offset arm and add another couple of LNBs to it for Hotbird and Astra 28.2, then use the Zone 2 dish for Hispasat, connect them all to a four way DiseqC switch and that should give you a great selection of interesting viewing.

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2cvbloke

Dang, beaten to the o'clock's!!!

Anyway, as for the SX1019/S, any seller of them will say it'll work with any dish, I remember a seller trying to flog an 80CM Lidl dish with one (for £25 total if I remember correctly) and I told him they weren't compatible and sent him a link to Satcure's page on those LNBs, and he said that Satcure was wrong and he was right, hmm, yeah, then 3 hours later he apologised and said he was wrong and that the LNB wasn't suited to round dishes...

There are some numpties out there...

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tavescan

Slightly ironic that Satcure are the company selling the SX109/S as being compatible with the Raven Gemini 90cm dish. I have e-mailed them to let them know of my measurements and the opinion expressed in this forum. Satcure insist that the Raven 90cm is an eliptical dish and should work best with an eliptical feed, but do suggest that my measurements may reflect the poor performance of the SX109/S generally.

Len

2cvbloke

You could try the SX1019/s on your standard minish and see how it performs, and if it's ok you could just swap the LNBs round if you like, that's assuming the 90cm has a spigot/finger/whatever they call it mount...

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