Toroidal (T90, T55) question.

[RimaNTSS]

Hi!
Could users of toroidal antennas share some pictures of set-ups? In addition, would you answer to question: “How many birds in your area you can receive on 90cm SAT dish?”
There is my T90 (picture is 2 years old), and I have possibility to tune to 32 satellites, of course antenna should be turned. But with 2 T90s it is possible to cover full arc. Location Riga, Latvia.

[burnsy]

You either have the best satellite meter in the world or you must have more patience then the Dali Lama. I have both a t-55 and t-90 but neither are set up at the moment guess I could post a picture of them sitting in the garage LOL. I have only ever had 7 sats on my t-90 and 5 on the t-55 in Northern Ontario Canada. You are the master

[Gold]

All I can say is WOW! That's amazing.

I have seen a similar set up before but it was done with a 6' Offset Dish

[Terryl]

That’s a lot of weight to hang up there, plus a wiring night mare, and one heck of a switching problem adding a second toroid.

Why don’t you go to a nice motorized system, you can pan the entire Clark belt with one smaller dish (39” to 48”) and 1 LNB.

If you don’t like the small time lag (10 to 15 seconds end of arc to end of arc) you could still use the toroid and a motorized system for the others.

[RimaNTSS]

10-15 (sometimes even more) seconds that is a lot of time, especially if I like to push buttons of remote control and expecting immediate reaction on the screen. Who knows, maybe sometimes I will install motorized antenna, but not for watching TV, more to have some practice.
Wiring is not such a big problem. I have plans to connect all 32 birds to my Dreambox by cascading of several DiseqCs.
And finally, this is not for simple watching TV, this is hobby – more for fun.

[Terryl]

They do sell 32 input switches, it may help a bit with the wiring....The powered ones will help to keep the switches and LNBs from overloading the power supply in the receiver.

Lookie here
http://www.emp-centauri.cz/products.php?page=products

[RimaNTSS]

I am planning to make switch with at least 40 inputs, and there is no need for external power. Attached you can see the plan itself and as well technical solution, I call it MegaDiseqc.

[Terryl]

Nice setup…..

But you may be missing something, all those switches need power, each switch will need anywhere from 20 to 60 mA of DC current to run them, the LNB's will also need power, and depending on the make they can use 60 to 200 mA of DC current.

Now most FTA receivers can only put out 500 mA of DC current, some can supply more.

It would be to your best interest to look up the current requirements of the switches that you are gong to use, the same with the LNB's, all this adds up, if you over tax the receivers power supply it could/will be damaged.

The next thing is insertion loss, most common DiSEqC switches have about 3 dB of insertion loss, the better ones have about 1.5 dB, add it up, every 3 dB is ½ of your total RF system voltage, with 1 switch you loose ½ of your RF voltage, add another and you loose half again.

Example, system RF voltage equals 100 micro volts, after 1 switch you have 50 micro volts, after a second you have 25 micro volts, after a third you have 12.5 micro volts.

So too many switches may drop the signal so low your receiver(s) wont work.

This is why its best to use a powered switch with many input to many outputs, it will work better.

Believe me as I have done this for over 45 years as an RF engineer.

[RimaNTSS]

Of course, I believe and totally agree with you, externally powered multiswithes are good products.
Yes, those DiseqCs have up to 3db signal loss, but at the same time signals from satellites are strong enough and diameter of antenna is bigger than necessary, so it basically compensates each other, and as a result there even still enough strength to compensate bad weather conditions. I would not say that mutiswithes are very popular in my country. I cannot imagine how person who lives in the apartment building can put multiswitch next to his antenna on the building’s roof, to power it and also to make it secure enough from stealing (and that is expensive). Another choice is to put for example 30 wires down to his apartment, no way.
But such a cascading of DiseqCs works without any problems and SAT receivers work with those cascades fine.