Twin LNB & Diseqc switches - advice needed

[kenny]

This will be a bit of a long post, but please bear with me as I need some help/advice here.

My current configuration consists of 4 dishes (3 fixed and a motorised) feeding a Technomate 6900 through a 4-way Diseqc switch.

I had the bright idea that I could exchange the single LNBs on all 4 dishes for twin LNBs. Then I planned to connect the 4 extra outputs to a second 4-way Diseqc which would then feed another receiver (Humax HD2000) in another part of the house. The 2 systems would be completely independent, so that for instance the TM6900 might be tuned to RAI on Hotbird, while the Humax might be simultaneously tuned to BBC on Astra 2. This seems perfectly feasible to me.

Before making the whole mod, I bought an Inverto twin which I wanted to test for performance. I installed it on the 28E dish, and for the purpose of an initial test, connected one output to the Diseqc going to the TM6900 and the second directly to the Humax, without going through the second Diseqc switch.

Now comes the part that I did not expect. Having tuned the Humax to an Astra 2D channel (for the moment, obviously specifying Diseqc off), I then went to check on the TM6900 and found that I could now only see Astra 2D here as well, but nothing from the other 3 dishes. However, as soon as I switch the Humax to standby, I can see channels from all 4 dishes on the TM6900, as before.

So - should my proposed scheme work as I expected or might the double lnb faulty somehow or is my scheme doomed to failure?

Thanks for any feedback.

[gerryl]

all fixed dishes should work Ok as it is a split system...however only one STB could control the motor!..the other will have to take what ever Sat feed its on

Have you looked at loftbox's and multiswitches!

what 4way are ye using!...

will be runnin some NEW CHIETA 4x1 DiSEqC Switch WSD-2041 Heavy Duty..soon meself for split system fixed and motor...:king-041:

[kenny]

In fact the motor is controlled by neither box! I have a 36v actuator under control of a 20-year-old Uniden positioner.

What I haven't tried yet (it was getting dark) is to include the 2nd Diseqc switch in the configuration, but I don't see that it should make any difference. It's as if the connection from the Humax to the double LNB is somehow feeding back a signal to the Diseqc switch connected to the TM6900.

As you say, I expected each system to be able to operate completely independently of each other......

As for the Diseqc switches I'm using. Not sure of the make of the original - but it has been working faultlessly for the past 10 years. The new one (as yet unused) is a "Best".

[gerryl]

see what you mean now as if its looped! through lnb!...best luck

[kenny]

Well, I tried it tonight using the second Diseqc switch, with similar results. Then I remembered I had an Invacom Quad lurking amongst all my sat gear. Swapped the twin Inverto for the Invacom - and hey presto - the config works as expected with each receiver able to select a different dish independently.

So - I guess the Inverto is faulty. I shall email them to see if they agree that it *should* work the way I'd like it to.

[AM556]

I suspect your LNB is a duel output rather than a twin output.

[kenny]

Not sure what you mean by "duel" - but I can assure you that it is marketed as a conventional "twin".

btw - I've never had a reply to my query from Inverto.......

[AM556]

Same as the difference between a quad and quatro. One works as if it were 4 universal LNBs in one housing with 4 independant outputs. The other is a single universal LNB with 4 seperate outputs (low V, low H, high V and high H).
I have a similar system to yours. One motorised dish with twin LNB feeding a darkbox, the other feeds through an 8 way Diseqc switch, along with 5 other feeds to a Technomate. Works a treat, just as you think it should.

[kenny]

Sure, I know about quattros - but (not wanting to labour the point) what use would half a quattro be ? I guess that's what you're alluding to by "duel" - I know that in the old days when just lo-band was used, there used to be lnbs with 2 outputs, one V and one H - but they'd be pointless now and are no longer made, I'd imagine. No this guy is definitely a twin. I'm picking up an MTI tomorrow which I trust is going to do the job. And I shall be returning the Inverto.

[Giga]

duel => dual?
Inverto twin, have you a model, type info for this?
how is the cabling from the stb's to the lnb's
separate cable from each STB?
Technomate 6900
- Diseqc switch
- lnb's
--Inverto twin

Humax
-Inverto twin

so some how the Inverto LNB connects the 2 circuits? That is not what should happen with a twin LNB?

[kenny]

Hi Giga - yes, that is how it is currently configured (with the old twin lnb that *does* work as anticipated). With this lnb, it works with or without the 2nd Disecq on the Humax side.

As for the dodgy Inverto, I hadn't realised that I'd not mentioned the model earlier. Its a IDLB-TWNL40-PREMU-OPP.

And as you say, its as if the Inverto is making a connection between the 2 circuits .... which should *not* happen with a twin lnb! No - I'm convinced that this particular lnb is faulty,and I'm rather disappointed that Inverto have not bothered to reply to my email.

[Giga]

this is what inverto says:

This LNB is a high-performance, high-end product. It was specialy selected from the production line and features an outstanding low noise figure and sets new standards of quality and reliability. It enables the reception of signal from one satellite and its distribution to up-to two single tuner Set-top box (or 1 in the case of a twin-tuner STB). It is ready for High Definition transmissions and provides excellent Noise Figure performance. Manufactured to the highest industry quality standards and designed to meet strict specifications, this LNB is an ideal solution for the satellite broadcast reception across Europe.
If you have each STB only connected to this LNB (just cable and no switch or other LNB's) can you view simultaneous a vertical transponder on one STB and a horizontal on other STB?

check the specifications against the old twin lnb

http://www.inverto.tv/products/product.php?section=1&id=69
maybe you can figure out the difference between the 2

[AM556]

Sure, I know about quattros - but (not wanting to labour the point) what use would half a quattro be ? I guess that's what you're alluding to by "duel" - I know that in the old days when just lo-band was used, there used to be lnbs with 2 outputs, one V and one H - but they'd be pointless now and are no longer made, I'd imagine. No this guy is definitely a twin. I'm picking up an MTI tomorrow which I trust is going to do the job. And I shall be returning the Inverto.

Indeed Kenny, I was thinking too far back, I got cought out by one many moons ago.
My Inverto is a IDLP-40TL+ which works a treat in your configuration. Very good prices around as it's now the "old" model but still a damned good spec.

[kenny]

Giga - yes, as you can see the spec of the Inverto suggests that things should work as expected - it is basically a "normal" twin output lnb. As for the old one I used - it is so old that there are no markings on it any more, so I have no idea of specs other than the fact that it's a twin.

Have now also got hold of an MTI twin, but the weather currently is stopping any further testing. Will hopefully get to the bottom of this at the weekend.

AM556 - are you confirming that you are using a twin Inverto behind 2 diseqc switches feeding 2 seperate receivers?

[AM556]

I have 3 dishes
one motorised
one with 4 LNBs
one fixed sly @ 28'

I have Technomate being fed by diseqc, which is fed from sly dish, 4 LNBs on fixed dish and one output from Inverto on motorised dish.

My Darkbox is fed from the motorised which has the Inverto.

There is no reason why you can't replace all your LNBs with dual ouput and run two independant systems.

[kenny]

I *may* have got to the bottom of this problem. I think that my original Disecq 4-way switch is faulty. I discovered this in a rather odd way after much recabling yesterday. Suddenly, I could no longer lock 11.992H on 7W. The signal strength was up and down like a yoyo - and I have always got a decent signal in the past. Other frequencies from 7w were fine. When I tried to get 11.992H on Astra1, I saw the same phenomenon - the signal strength would not stay steady. Trying to eliminate the variables, I swapped the Diseqc switch I was using - and all returned to normal! Now frankly, this makes no sense to me - Any experts out there care to offer an explanation?

[kenny]

Well, I don't understand it - but it does seem that the original problem *was* caused by a faulty Diseqc switch. This evening I replaced it with another new one and my new configuration is now working as expected with each of the 4 twin lnbs (including the original Inverto that I suspected as bad) feeding my 2 receivers independently.

So that's that problem sorted!

[Giga]

Great that you could sort things out and all works ok now