Adjusting dish to Hotbird using Sky mini dish

[Captain Jack]

I don't think there's anything off the shelf for Sky minidishes. You'd have to fabricate something yourself... with zipties and duct tape if need be (as a "temporary" measure).

One thing I'd suggest first, is removing both LNBs and try to find 13E and 19.2E without fixing LNBs to anything. Align the dish to 13E (as it is now?) and move the LNB with your hand to find 19.2E. It should be just a couple of cms away.

Another potential solution is to align the dish to 16E as your prime satellite but then setup the two LNBs offset to 13E and 19E. Doing it this way will increase the gap between the two satellites. Again, you'd have to fabricate something yourself.

 

[Copecchia]

The other option I also thought, would be to center the dish to 19.2 instead and then 13E would be sitting on the left where there is no extra space used and sit right next to it. I am only afraid that once I do this I would loose signal over 13E in this way but it will be worth give it a go.
Pretty much like Captain Jack advised by the way.

 

[william-1]

Another option to consider is a 60cm clear dish







This dish will support a 3 Lnb set up for example:-
28 east + 19 east + 13 east or 19 east + 13 east + 7 east.

 

[Captain Jack]

Yep.. or a completely separate "Selfsat" type "dish" for one of the satellites you need. It's not a dish...

 

[a33]

@Copecchia:
Did you already measure the effective focal distance of your dish?
Then we can calculate what distances you have to find a solution for.

Greetz,
A33

 

[Copecchia]

@Copecchia:
Did you already measure the effective focal distance of your dish?
Then we can calculate what distances you have to find a solution for.

Greetz,
A33

Not yet, but I will in the next few days. Does this need to be the exact distance from the end of the arm or from the actual LNB surface to the Dish?

 

[Copecchia]

Thanks William1 and Captain Jack but unfortunately like I stated before the only option I am allowed of is t work out the best out of the Zone 1 Sky Minidish. Anything different will be rejected by the planning officer because of some stupid neighbors who had nothing else to complaint with.

 

[Copecchia]

@Copecchia:
Did you already measure the effective focal distance of your dish?
Then we can calculate what distances you have to find a solution for.

Greetz,
A33

It's about 26-27cm arm length from dish to lnb bracket.

 

[a33]

It's about 26-27cm arm length from dish to lnb bracket.

It looks like you measured the arm length?
Better is measuring at 40% of dish height, as I wrote before (see below, the underlined part).
(I'm still thinking about a method using three simpler measures of the mounted dish, and then calculating effective focal distance from these three measures, more precise than this 40%-rule of thumb. That may take still a few months, though... )

If your 40%-measurement is about 35 cm, then horizontal distance would be about 4,6 cm.
If your 40%-measurement is about 40 cm, then horizontal distance would be about 5,3 cm.
If, however, your 40%-measurement is indeed about 26,5 cm, then horizontal distance would be about 3,5 cm.

For the spacing of LNBs (in inches or cm) you can use the formula:
distance = fG x ( (dA x PI) / 180), with [focal distance = fG, Azimuth difference = dA]
Or easier: distance = fG x dA x 0,01745
(see Multifeed installation and exact calculation of LNB position )

For London 51.4N, 0.3W, dA(13 and 19,2E) = 7,55 degrees (and elevation difference = 1,47 degrees)
For effective focal distance ..... more easy is the rule of thumb for an offset dish that you measure the distance between front of LNB-holder and dish-surface at 40% of the dish-height (40% from bottom of dish, so 60% from top of dish), and use that value as the effective focal distance.

Now you can calculate the needed distance between the two LNBs (or the distance between the two necks of a monoblock LNB ).
A few mm's off would not be a problem.

BTW: The holder of the two LNBs should be at an angle of exactly 11 degrees to the horizontal in London 51.4N, 0.3W; the LNB for 13E lower than the 19E, as to adjust to the difference in elevation.

Greetz,
A33

 

[Copecchia]

It looks like you measured the arm length?
Better is measuring at 40% of dish height, as I wrote before (see below, the underlined part).
(I'm still thinking about a method using three simpler measures of the mounted dish, and then calculating effective focal distance from these three measures, more precise than this 40%-rule of thumb. That may take still a few months, though... )

If your 40%-measurement is about 35 cm, then horizontal distance would be about 4,6 cm.
If your 40%-measurement is about 40 cm, then horizontal distance would be about 5,3 cm.
If, however, your 40%-measurement is indeed about 26,5 cm, then horizontal distance would be about 3,5 cm.



Greetz,
A33

From 40% lower dish area the LNB surface is about 24-25cm from that dish area.
Yes the previous was the actual arm lenght from dish to bracket.

 

[a33]

From 40% lower dish area the LNB surface is about 24-25cm from that dish area.
Yes the previous was the actual arm lenght from dish to bracket.

Well, if LNB surface is about 4 cm in front of LNB bracket, then fG would be about 28 cm and horizontal distance between LNBs would be about 3,7 cm. So LNBs 3,7 cm apart would be best.
I believe that with LNBs (necks) till about 4,7 cm apart (maximum!!) you could probably have reception (both LNBs then 0,5 cm off), but I'm not sure about this tolerance. And it would mean worse reception quality, then.

I guess the LNBs that you have have a diameter of about 6 cm? With these it would be impossible.

I don't know what is the distance in these 3degree monoblocks you mentioned. Have you checked already? Or does anybody else on this forum know?

Otherwise you need slim LNBs. The ALPS Rocketfeeds LNBs would probably do (heads of 4,2 cm). Or other slim LNBs (there are a few types). But then the problem remains, how to make a bracket for this distance.
And of course, with slim LNBs you would need rain-protection (as they are more sensitive to rain in regard to signal quality).

greetz,
A33

 

[Copecchia]

Well, if LNB surface is about 4 cm in front of LNB bracket, then fG would be about 28 cm and horizontal distance between LNBs would be about 3,7 cm. So LNBs 3,7 cm apart would be best.
I believe that with LNBs (necks) till about 4,7 cm apart (maximum!!) you could probably have reception (both LNBs then 0,5 cm off), but I'm not sure about this tolerance. And it would mean worse reception quality, then.

I guess the LNBs that you have have a diameter of about 6 cm? With these it would be impossible.

I don't know what is the distance in these 3degree monoblocks you mentioned. Have you checked already? Or does anybody else on this forum know?

Otherwise you need slim LNBs. The ALPS Rocketfeeds LNBs would probably do (heads of 4,2 cm). Or other slim LNBs (there are a few types). But the the problem remains, how to make a bracket for this distance.
And of course, with slim LNBs you would need rain-protection (as they are more sensitive to rain as regard to signal quality).

greetz,
A33

They are standard LNB's, yes around 6 cm, the bracket is also there as per pictures previously posted.
I am not sure right now what is the distance between 13e and 28.2e but it looks like the same separation I had for 13e and 19.2e on the 80cm Dish, approximately 2-3cm.

 

[a33]

Well, with my way of calculating, for 13E and 28,2E I would come to about 8,8cm heart to heart distance of the LNBs, using fG=28cm and 18,0 degrees azimuth difference for London.

The 2-3 cm you mention, is that between necks or between heads of LNBs?
Or, asked from another viewpoint: what is the difference heart to heart?

Greetz,
a33

Edit: BTW the 4,3 degree (Inverto?) monoblocks for 60cm dishes, used in the netherlands for 19E and 23E, have a distance of 38mm I believe. They could fit well?

Edit2: In the photo I cannot see how the bracket is fitted to the arm. Do you still use an original LNBholder, PLUS the multifeedbracket? Or is the multifeedbracket somehow fitted to the arm, directly?

 

[Copecchia]

Well, with my way of calculating, for 13E and 28,2E I would come to about 8,8cm heart to heart distance of the LNBs, using fG=28cm and 18,0 degrees azimuth difference for London.

The 2-3 cm you mention, is that between necks or between heads of LNBs?
Or, asked from another viewpoint: what is the difference heart to heart?

Greetz,
a33

Edit: BTW the 4,3 degree (Inverto?) monoblocks for 60cm dishes, used in the netherlands for 19E and 23E, have a distance of 38mm I believe. They could fit well?

Edit2: In the photo I cannot see how the bracket is fitted to the arm. Do you still use an original LNBholder, PLUS the multifeedbracket? Or is the multifeedbracket somehow fitted to the arm, directly?

Sorry, I should have said that between the center of the two collars there are 8cm of distance.
The bracket is held by collars as per item below which I have cut to size to make the installation as much discreet as possible.
I use the same LNB Holder as the one used with MK4 Dishes although the collar is 40mm instead of standard 37mm got on ebay.

 

[a33]

If 8,0cm is the best fit for 13E and 28E (i'm assuming it is, then?), then fG=25,5cm (not by rule of thumb, but in reality!).

The distance between LNBs (heart to heart) for 13E and 19,2E in your location should be 3,4cm, then.
If I were you, I would go for a monoblock.

Greetz,
A33

 

[Copecchia]

Ues

If 8,0cm is the best fit for 13E and 28E (i'm assuming it is, then?), then fG=25,5cm (not by rule of thumb, but in reality!).

The distance between LNBs (heart to heart) for 13E and 19,2E in your location should be 3,4cm, then.
If I were you, I would go for a monoblock.

Greetz,
A33[/QUOTE

If I understand well 3.4cm separation with a monoblock would be just not possible as the minimum distance heart to heart (center of lnb to center of the other) would be at least 6cm considering the size of these. There are also 3 Degrees monoblocks but they come with a huge 60cm collar and beside I would not know if that is the correct degree separation between 13e and 19.2e?

 

[Copecchia]

3 degrees monoblock with 40mm adapter, according 3 degreed are the right separation within your schema?

 

[a33]

Yes, the 3 degrees monoblock for 80cm dish has also distance heart to heart of 38 mm.

Your picture would be the twin:
Twin Monoblock 23mm LNB ,3° for 80cm dish, IDLB-TWNM22-MNOO3-8PP
Inverto - IDLB-TWNM22-MNOO3-8PP -

Or you could choose the single: IDLB-SINM62-MNOO3-8PP
Inverto - IDLB-SINM62-MNOO3-8PP -

Or the quad: IDLB-QUDM22-MNOO3-8PP
Inverto - IDLB-QUDM22-MNOO3-8PP -

(These have the same dimensions as 4,3 degrees for 60 cm (as for in the Netherlands), but I guess these are without pre-skewed built-in antennas as needed for the Astra1 and Astra3.)

I hope the thickness of your holder (along with the adapter ring) fits nicely between the necks of these monoblocks. Otherwise you must make a somewhat excentric adapterring.

Well, I think I've done enough searching for you now?

Greetz,
A33

 

[Copecchia]

Yes, the 3 degrees monoblock for 80cm dish has also distance heart to heart of 38 mm.

Your picture would be the twin:
Twin Monoblock 23mm LNB ,3° for 80cm dish, IDLB-TWNM22-MNOO3-8PP
Inverto - IDLB-TWNM22-MNOO3-8PP -

Or you could choose the single: IDLB-SINM62-MNOO3-8PP
Inverto - IDLB-SINM62-MNOO3-8PP -

Or the quad: IDLB-QUDM22-MNOO3-8PP
Inverto - IDLB-QUDM22-MNOO3-8PP -

(These have the same dimensions as 4,3 degrees for 60 cm (as for in the Netherlands), but I guess these are without pre-skewed built-in antennas as needed for the Astra1 and Astra3.)

I hope the thickness of your holder (along with the adapter ring) fits nicely between the necks of these monoblocks. Otherwise you must make a somewhat excentric adapterring.

Well, I think I've done enough searching for you now?

Greetz,
A33

No, the problem is the actual Dish "own" collar that takes spaces on it's right end side but I guess I will mount it to center the dish on the other LNB regardless of whether will be a monoblock or a slim single one.
One last thing please, can I draw the conclusion that on my dish according to your calculation, 6 degrees spacing of a regular dish would be equivalent to 3 on mine? Which means also that 1 degree on mine is equal to 2 on a regular dish?

 

[a33]

No, the problem is the actual Dish "own" collar that takes spaces on it's right end side but I guess I will mount it to center the dish on the other LNB regardless of whether will be a monoblock or a slim single one.

OK, I see; I forgot that you posted a picture of your holder/collar earlier on.

... can I draw the conclusion that on my dish according to your calculation, 6 degrees spacing of a regular dish would be equivalent to 3 on mine? Which means also that 1 degree on mine is equal to 2 on a regular dish?

Huhhhh? You want to compare angles with spacing? A degree stays a degree, however far you go. And I guess your dish is 'a regular dish', too, so your question really is unclear .

If you mean to ask if the spacing belonging to a "80cm dish, 6 degrees arc-difference LNB" should be halved for your dish (as you can receive both satellites with a "80cm dish, 3 degrees arc-difference LNB"); then yes it is possible that that would be about true.

My reserve in saying yes fullheartedly lies in the following:
The manufacturers' classifications of monoblocks are somewhat unclear and confusing, I think.
It all depends on how many degrees azimuth they mean with the given amount of degrees arc; and what focal distance they mean with the given diameter. See the formula in my posts: that gives the relevant variables.
As many offset dishes have about the same f/D-ratio (see message #34), you can compare dishes by diameter instead of by focal distance, that would be right. But only if they really have the same f/D!
And the one important measure, the distance heart to heart between the necks of the monoblock-LNB, you have to find out for yourself because that is hardly given in the specs!
And, last, we have calculated your needed distance only by rule of thumb and by comparing to your measurement with 13E and 28E. It will work with the "3 degree monoblock", I'm quite sure about that, but we haven't measured the 'perfect fit' for your location and your dish.

So as these factors are a bit unclear, the conclusion you want to draw on these lines is not 100% garanteed.

Greetz,
A33