Monoblock or 2 seperate lnbs?

questioner

Hi Everybody,

I have a 70cm dish with 2 old receivers - Humax fox and an Echostar, and a universal lnb. I'm wanting to receive Hotbird 13 and Astra 19 at the same time instead of moving the dish.

From what I've read on the forum the dish size for a monoblock ideally should be 80cm? What I was thinking of was getting a monoblock and giving it a go, and it that doesn't work I can then, with my present single lnb, plus the monoblock, together with an external DiSEqC switch (silly question this: would a 'T' connector work as well?, also do I still need an external DiSEqC switch even though there's a DiSEqC facility with both receivers?) and an offset clamp produce an alternative set up. Does this sound like a reasonable procedure?

Also I have found when on Astra the screen breaks up on some transponders - signal level/quality only around 45% - no matter what I do with the dish or with skewing. I have an lnb with has a 0.6 low noise figure. Would I get a better signal with a lnb rated at 0.2 or 0.1db?

Can you tell me how to access parts from suppliers associated with this forum?

Thanking you in advance.

guest

I have fixed a Monoblock to an old Sky "Analogue" Dish, which is probably marginally smaller than your nominal 70cm thingy, and it works perfectly with full Strength and (more importantly) Quality on all Hotbird and Astra 1 Channels.

Yes, Monoblocks are indeed designed for optimal use with 80cm Dishes, but practical experience suggests anywhere between 60cm and 90cm will be fine in much of the UK.

The only exception is for Zone 2 Sky "Digital" Dishes, where it is not quite so easy due to the squashed shape: Proper Dishes are always slightly higher than wide (to present a circular view for incoming signals) whereas Sky Dishes are wider than they are tall, for Beamwidth reasons.

As regards switching between the Receivers, don't discard simple solutions like A/B switches (obviously this gives you an either/or choice for the Receivers), or IF Loop Through (where, again, only one Box can be "Master", but you would be able to use the "slave" to Receive Channels of the same Polarity and Band as the "master").

satelliteman

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Monobloc will be ok with 70cm dish. Seperate LNb's and bracket will have more room for final adjustment of course. Both strong satellites so not much to worry about, either option.

Monobloc LNb's have an internal DiSEqC switch and the receiver only needs DiSEqC 1.0 or mini DiSEqC commands to switch from one to the other.

satelliteman . ..... A Detailed DiSEqC Motor Installation Set Up Guide > HERE Quick Reference Guide also > HERE Satellites UK site Advertisers . An Installers Choice ...... Follow us on .

Robbo

I have used a monoblock on a 60 cm perforated dish (not by choice), but it worked fine for 13 and 19E, that was in central London.

questioner

Many, many thanks for all your help - Rai Uno, Satelliteman and Robbo.

I understand very little as to DiSEqc terminology. With my Echostar, on the television screen it says at the top 'DiSEqC 1.2'; below it gives the choice of 'OFF' or 'ON'.
Does this mean that this particular receiver will be able to be used with a monoblock.

Thank you

Robbo

You need Diseqc 1.0. As far as I know, every receiver apart from the Sky dodgybox is capable of that, check the menus further, or the manual.

satelliteman

or some receivers have an option shown as Mini-DiSEqC

satelliteman . ..... A Detailed DiSEqC Motor Installation Set Up Guide > HERE Quick Reference Guide also > HERE Satellites UK site Advertisers . An Installers Choice ...... Follow us on .

questioner

Thanks for you continued support.

In my Echostar receiver menu there's a section on 'User lnb', and below it it says 'DiSEqC repeat' and then there's a choice of 4 numbers: 0, 1, 2, or 3. Is this useful for the monoblock?

With my Humax Fox receiver menu next to 'DiSEqC Input' there's 7 choices: Disabled, Tone Burst A, Tone Burst B, DiSEqC A, DiSEqC B, DiSEqC C and DiSEqC D. Is this useful for the monoblock?

Thank you

Robbo

The A,B, C and D on the HUMAX should do it.

On the Echostar, the repeats option is not what you want, that repeats the diseqc commands your selected number of times, useful when cascading switches. But I could been misled by your description, because they are the numbers I would have expected.

A screenshot perhaps?

questioner

Cheers Robbo.

One last question: another reason for trying a monoblock is that when I use my present universal lnb on Astra 19 the screen breaks up allot; there's a signal quality reading of only around 40/45%. The db on the lnb is 0.6. I see now that lnbs can be 0.1 and 0.2 dbs. Could my 0.6 rated lnb be the reason for the low signal quality reading? I've tried skewing and various positions with the dish with no improvement. With the same lnb I receive an excellent signal level/quality(90+/80+) when on Hotbird 13. Again would another better rated lnb make a difference? I receive this screen break up with both my receivers - Echostar and Humax.

Robbo

A 0.6 dB noise figure coupled to a 70cm dish would be fine for reception of Astra 19.2E. Sounds like you may have another problem, eg dish alignment, LNB Skew, obstruction, cable too long, LNB faulty etc.

Might be worth trying another LNB, it might as well be a monoblock.

guest

A 0.6dB should give more than adequate performance on a strong cluster like 19.2E.

In practice, the benefits of using one claimed to be 0.1dB or 0.2dB are limited as this is the best figure achieved across a small portion of Ku Band: The Noise Figure vs. Frequency characteristics are nothing like flat!

When you move the existing arrangement between 13E and 19.2E, are you making sure you depress the Dish Elevation a little? Your symptoms, given everything you've reported, are consistent with inadequate alignment.

peapod1

I'm using an echostar with a fixed dish/monoblock for astra1 and hotbird.
To configure it for this set-up, see item 2.1 in section 6 of the manual - to change setup of the receiver, press menu, select the hammer symbol, then select the dish symbol and make selections. My selections are :

Fixed
Easy
2
LNB
1.4
LNB1 - Universal - Astra1 - Port 2
LNB2 - Universal - Hotbird - Port 1

I think that is because the dish is aligned on Hotbird, but I'm no expert.
Hope this helps you.

questioner

There's a mystery here! As I said, the present set up gives excellent signal level/quality readings for Horbird but not for Astra. I have also tried with dish elevation. May be I should just try with the monoblock?

questioner

Thanks for your response Peapod1, I will definitely give that a go when I get hold of a Monoblock.