Toroidal T90 or Maximum T85 ?

[Fano]

Hi Guys
Looking for a bit of advice on these two dishes please.
I have sold my 1m Gibertini which served me well for the last 2 years and I am switching to a fixed dish as my motor packed it in.
I like channel hopping so the faster switching will be a big advantage.
I ideally want to receive 28e,19e, and 13e but I'd also like to receive 23.5e,16e (New Sat due to launch next month),7e and 1w.

I was leaning towards the T90 but there are a few drawbacks.
Firstly its a monstrous dish and as it has to be wall mounted I'd need a special wall mount for it as my T brackets arent strong enough.

The T85 is lighter and will attach to my current wall mount as it doesnt require a 6cm pole.
As my house is dashed this saves me alot of hassle and grief from the missus .:-Nooo


Obvously the T90 has a higher gain but its also more expensive.

What kind of performance would the T85 give me ,I've read its similar to a 70cm dish ?
This comparison seems to indicate the T85 performs as an 80cm dish between +/- 10 degrees and 60cm outside that to +/-20 degrees.
_http://www.satshop24.de/Messprotokoll.pdf
The T90 performs as a 90cm dish +/- 10 degrees.80cm outside that to +/-20.
So it seems the T90's gain is alot more constant .

Is it possible to get 3 degree spacing on the T85 ,for 13e,16e and 19e ?

I'm living in Ireland btw.
Would the T85 be sufficient for my needs or would be better off to get the T90 ?
Thanks

 

[Robbo]

If the 85 performs like a 60 outside the 10 degree, you are going to struggle with 1w I believe. Would have thought that you'd be able to pack out a 50mm diameter pole a bit, so that a 60mm mount would fit snugly enough, I've had to do that with a T55, so that a 1.5 inch diameter pole can be used (needs 45mm). I used a short section of a 1.5inch alloy mast, and sliced it down one side so that it could be opened out a bit and slipped over the top.

 

[Fano]

Would have thought that you'd be able to pack out a 50mm diameter pole a bit, so that a 60mm mount would fit snugly enough, I've had to do that with a T55, so that a 1.5 inch diameter pole can be used (needs 45mm). I used a short section of a 1.5inch alloy mast, and sliced it down one side so that it could be opened out a bit and slipped over the top.

Thanks for the reply Robbo,
I can replace the 50mm pole on the T brackets with a 60mm pole easily enough,its a straight swap.
I'm just worried that the 14kg weight may be too much to risk.

If the 85 performs like a 60 outside the 10 degree, you are going to struggle with 1w I believe.

I was planning to centre the T85 on 10E,that way the +/- 10 degrees would cover both 16e,7e and 1w ,the 3 weakest satellites.
28e and 22.5e would be seeing an equivalent 60cm dish which is sufficient.

 

[Fano]

I've been doing some more research on the T85 and it looks like a nice dish but there are a few flaws.
Its quite small at 90cm by 70cm,it could do with being 10cm higher.
Its focal point is +/- 8 degrees.
Its minimum lnb spacing is 4.5 degrees so i'd have to modify it to get 13,16 and 19e.

I found a comparison of different multifeed dishes on another forum,its quite interesting,I will post it here.

Basically it shows that over the range 1w to 28e that a normal 1m dish with a multifeed outperforms the T85 .
To be honest it even looks like a standard 80cm dish outperforms the T85.
The performance of the T90 is very solid over a large satellite range.

Its not an exact scientific test but it seems interesting none the less.

 

[Fano]

Update:
I have been scouting my site for a possible ground location for a T90 and have found one.
Only problem is that it is at the bottom of my garden .
I would have to run the cable under the grass for 25 yards and then another 5 yards across the patio.
Looking at 32 yard cable run.
Is that feasible or too impractical /cable losses ?

 

[Lazarus]

Should be fine with a decent quality cable.

 

[Fano]

Should be fine with a decent quality cable.

Thanks Tivu
Would I need to run the cable in some sort of conduit/wavin pipe to protect it ?

 

[RimaNTSS]

There are special pipes available in different diameters. In the picture I have 20mm pipe insight it one SAT cable and couple of internet cables go to my neighbor house. I would say, it is better to use such a protection plastic pipe than lay SAT cable directly to dirt.
Edit: and lengths of SAT cable to neighbor's receiver is about 50 meters and still signal is OK.

 

[Fano]

Thanks Rimants
Looks perfect for the job.
How deep a hole would I need to dig for a pole for the T90 ?

There are special pipes available in different diameters. In the picture I have 20mm pipe insight it one SAT cable and couple of internet cables go to my neighbor house. I would say, it is better to use such a protection plastic pipe than lay SAT cable directly to dirt.
Edit: and lengths of SAT cable to neighbor's receiver is about 50 meters and still signal is OK.

 

[Ghostleader]

Quite surprised at how average the T85 performs, I have a 80cm ISS dish with non brand specific multi LNB brackets & have a massive 33 Degree seperation between birds end to end (5W to 28E).

 

[Fano]

Quite surprised at how average the T85 performs, I have a 80cm ISS dish with non brand specific multi LNB brackets & have a massive 33 Degree seperation between birds end to end (5W to 28E).

Yes ,I was very disappointed .
However I'm not sure of the validity of the results,I found them on a German site.
I cannot see how an 80 by 70cm dish can outperform the T85 at 7e and 10e and more importantly at 16e ,it doesnt make much sense.
The T85 is 73 cm high x 93 cm wide so the extra width would help on offset birds.
In the middle ,near the primary focused satellite,I'd expect the performance to be similar to that of an 80cm dish.

 

[RimaNTSS]

How deep a hole would I need to dig for a pole for the T90 ?

I have heard that it is better to dig deeper than ground freezes at the winter time, so than there are no movements during different seasons. So I bettoned 130cm down.

 

[Fano]

130cm Thats a bloody deep hole
Could be akward to dig a hole that deep as there is sewage piping in that area ,I'd be afraid of hitting it .
Its the only gap in the trees surrounding my garden.
This T90 may be just too big and akward I fear.

 

[RimaNTSS]

Probably 1 meter (or even less) down would also be enough. I have seen people making 3 holes and connect them on tops to make stable platform.

 

[Fano]

Thanks Rimants,will look into it.

 

[Fano]

Another alternative I thought of would be using a 1m dish and a multifeed adapter to get 28e to 1w.
I was thinking about buying 2 of these and putting them on a Gibertini 1m dish .
I'd use one bar but the lnb holders off both.
I think I can get 3 degree lnb seperation using these adapters without modification and the performanceo on the central satellites would be good.
I'm not sure about the performance on the peripheral satellites though and I'm also wondering if 7 lnbs and its associated wiring may be too much load on the arm .
Would this be a better option than the T85 for 28e to 1w ?

 

[sonnetpete]

I wouldn't worry about overloading the arm. The Triax bar is supporting 8 LNB's and the wiring and Gibertini's have a build quality akin to a Sherman tank.

The only seperation problems you might have is trying for sats where the LNB's will be touching. I've used Alps LNB's which seem to be a good compromise between 'normal' heads and the very narrow 'muti connect' type which (from what I've read) seem to suffer more with rain fade. Perhaps someone with more experience could comment about the relative merits of those dishes. To me there doesn't seem to be that much to choose between them.

 

[Fano]

I wouldn't worry about overloading the arm. The Triax bar is supporting 8 LNB's and the wiring and Gibertini's have a build quality akin to a Sherman tank.

The only seperation problems you might have is trying for sats where the LNB's will be touching. I've used Alps LNB's which seem to be a good compromise between 'normal' heads and the very narrow 'muti connect' type which (from what I've read) seem to suffer more with rain fade. Perhaps someone with more experience could comment about the relative merits of those dishes. To me there doesn't seem to be that much to choose between them.

Thanks Pete
The Gibertinis are well made no doubt of that ,I'm just worried the arm could wobble in the wind.

I plan on using Sharp and Alps lnbs ,irrespective of the dish ,they have a narrower top.
The T85 will probably require an Inverto multiconnect for 16e though as there is very little room between 13 and 19e.
I may be able to squeeze an Alps in there.
Will require diy though.

I think the T90 may have to wait,the missus has decreed that she wont tolerate such a big dish on the wall and my efforts to ground mount it at the bottom of the garden have been shot down too.:mad:

So looks like its the T85 or a 1m Gib.

 

[sonnetpete]

Thanks Pete
The Gibertinis are well made no doubt of that ,I'm just worried the arm could wobble in the wind.

The T85 will probably require an Inverto multiconnect for 16e though as there is very little room between 13 and 19e.

Blimey, you live in Ireland, when the wind blows doesn't an arm with one LNB on wobble LOL?

On the TD88, I have 16°E on a Black Ultra and 19°E on an Alps. There's no problem with seperation, only getting the elevation of 16°E peaked up. I've decided to put up with it until the new sat for that position comes into service (or ends up in the ocean).

 

[RimaNTSS]

Fano!
How do your wife knows that T90 is bigger than T85 or Gib 1m? Tell her that T90 performs worser than 1m Gibertini. Maybe she agrees to have T90.
BTW, I have one Sharp LNB, picture you showed, and I like it. I put it for reception of 7*E (between 4,8*E and 9*E). I think I will buy some more of those SHARP.