Zone 1 or Zone 2 with 40mm LNB

[statalite]

Hi all,

Does anyone have any general guidance on the difference in performance effects between the LNBs at 37mm collar with an 'oval' face and LNBs with a 40mm collar and a 'round' face?
I do appreciate different brands etc.
The reason I ask is I currently have a 40mm and am wondering if its worth getting a 37mm collar LNB?
TIA.

 

[SimonE]

Tia, the LNBs with 37mm collar and oval mouth were supposed to work well with oval SKY dishes. That combination is an attempt to get the best gain out of the dish while trying to avoid interference from adjacent satellites. Here I have a zone 2 SKY dish with a 40mm round entry LNB. That works fine for me with a good margin when thunder storms occur. SimonE

 

[statalite]

TIA = thank you in advance.

 

[ozumo]

Never had a Sky LNB outperform an Inverto Black Ultra on a zone 2. Saying that my Sky LNBs are at least a decade old.

 

[statalite]

Tia, the LNBs with 37mm collar and oval mouth were supposed to work well with oval SKY dishes. That combination is an attempt to get the best gain out of the dish while trying to avoid interference from adjacent satellites. Here I have a zone 2 SKY dish with a 40mm round entry LNB. That works fine for me with a good margin when thunder storms occur. SimonE

Hi SimonE,
When you say supposed to work, is this not strictly true? It's that gain margin, frkm what you describe it doesn't sound too big.

 

[Channel Hopper]

I took one of the early quad LNBs apart a couple of days ago, and found this under the bonnet.

Whilst there is a general formula that confirms elliptical reflectors work best with 'oval' feeds, the downlink power and transmission standards can already cope with weather and climate conditions, misalignment by the average Sky installer, sagging of the wall bracket after a few weeks, cable lengths , cable and connector quality , indifferent tuners in Sky boxes, plus growth of flora to a certain extent.

I really wouldn't worry about it.

 

[davemurgtroyd]

There are two main factors here
Firstly whether the "circular" lnb is seeing all of the dish or merely a smaller circle at the centre of the dish - thus giving the effect of a smaller dish (probably the case with a zone 2 dish).
Secondly if the lnb is seeing all of the dish then it is also seeing outside the dish and probably picking up noise (from reflections from other satellites from a wall behind the dish etc) so reducing signal quality.
Another factor is also mounting the "circular" lnb so that its sensors are at the focal point of the dish - adjustment of this is not easy on Sky dishes.
All this is dependant on lnb and siting of dish

 

[ozumo]

If the weather is ok I will test an old Sky single vs a basic Inverto on a 28e zone 2 tomorrow.

 

[ozumo]

WNC F18 or FI8 single

 

[ozumo]

TP	Sky WNC FI8	Inverto Black Eco (green feed cap)	Inverto Black Ultra Single
10714h 22000 UK	14.8db	14.8db	14.3db
11038v 22000 EU	13.1db	13.0db	13.0db
12382h 27500 UK	14.8db	14.8db	14.8db
12441v 29500 EU	16.3db	16.6db	15.6db

Conditions were overcast/very light drizzle. Very little difference between the Sky LNB & Inverto Eco. Wonder if the IBU was overloading the meter, or maybe it's just time for the bin

 

[Channel Hopper]

Gain (or signal strength) has very little to do with the overall quality of signal once there is a minimum threshold reached.

A better guide is the BER (bit error rate), or Eb/N0 if your receiver has the right on screen parameters.

 

[Adam792]

TP	Sky WNC FI8	Inverto Black Eco (green feed cap)	Inverto Black Ultra Single
10714h 22000 UK	14.8db	14.8db	14.3db
11038v 22000 EU	13.1db	13.0db	13.0db
12382h 27500 UK	14.8db	14.8db	14.8db
12441v 29500 EU	16.3db	16.6db	15.6db

Conditions were overcast/very light drizzle. Very little difference between the Sky LNB & Inverto Eco. Wonder if the IBU was overloading the meter, or maybe it's just time for the bin

Interesting! Thanks for sharing those results

Thinking those Black Ecos might be a good choice to use with a universal multi-bracket For 7-13-19E (or maybe 13-19-28.2E), as they're a bit narrower, and it seems like the performance on the minidish is pretty good!

I currently have two Sky Zinwell quads cable tied together on my Zone 2 for 13/19, which works fine but is a bit of a lash up.

 

[ozumo]

I'm no expert on feed horns but I'd have thought the further away from 28e you get, the worse a Sky LNB with oval feed horn will perform due to the skew.

I use the black eco for 19e offset on a multi bracket on the 28e zone 2, the bracket hangs off the main LNB so I needed a light one to stop the LNB holder sagging. Black eco weighs virtually nothing and works well.

 

[Adam792]

I'm no expert on feed horns but I'd have thought the further away from 28e you get, the worse a Sky LNB with oval feed horn will perform due to the skew.

I use the black eco for 19e offset on a multi bracket on the 28e zone 2, the bracket hangs off the main LNB so I needed a light one to stop the LNB holder sagging. Black eco weighs virtually nothing and works well.

Cheers,

Will definitely give it a go in that case! Need to get my hands on a couple of the eco LNBs.

 

[ozumo]

I wouldn't say the black eco is anything special though it's light, small and very cheap

 

[statalite]

I have set up my first ever dish today which is a zone 2 at 28.2e with a 40mm Inverto premium quad.

I used a cheap beeper and a gtmedia v-71 finder to get a stable signal, when I connected by Dr HD D15 to check the decibel reading I was surprised that these were lower than a zone 1 with a 37mm sky lnb, on my zone 1 the highest ones are 17.9db, but on my zone 2 today I got around 13db max.

Do I have unreasonable expectations or should I still be able to tweak to get more out of the zone 2?

 

[ozumo]

LNB position & skew can gain several db. No way should a zone 1 outperform a zone 2. Concentrate on the weakest transponders rather than the strong ones.

You could always try the Sky LNB from the zone 1 on the zone 2.

 

[statalite]

LNB position & skew can gain several db. No way should a zone 1 outperform a zone 2. Concentrate on the weakest transponders rather than the strong ones.

You could always try the Sky LNB from the zone 1 on the zone 2.

Thank you for your reply, in terms of positioning the lnb in the holder which is fixed, adjusting the neck position closer/further away? I have tried this along with the skew but will have another go tomorrow.

The lnb chart that you posted with decibels, were these frequencies your weakest transponders?

There isn't a possibility to use the sky lnb. I don't want to mess up the setup that other people in the house use.

 

[a33]

I used a cheap beeper and a gtmedia v-71 finder to get a stable signal,

A sat-beeper is excellent stuff to FIND a satellite signal,
but for fine-tuning a dish to maximum quality level on a satellite it is not the best equipment (understatement).

Ho did you fine-tune? Did you check on both 28.2 channels, and 28.5 channels?

greetz,
A33

 

[ozumo]

Thank you for your reply, in terms of positioning the lnb in the holder which is fixed, adjusting the neck position closer/further away? I have tried this along with the skew but will have another go tomorrow.

Yes exactly as you say, it took a fair bit of tweaking to get the best from my non Sky LNBs. Also be aware It's very easy for a dish to move slightly when tightening the bolts up fully.

The lnb chart that you posted with decibels, were these frequencies your weakest transponders?

No, I just picked one UK beam & one europe beam TP at the low end of the frequency range, and the same from the high end. I will try to find my weakest TPs in the morning