Channel Master 1.8m with new Feedhorn WORSE!

[Trust]

On their site :



OCTAGON OPTIMA LNB Single OSLO PLL : EAN (4260189991124) VPE 100 Stück, UVP 14,90 €
OCTAGON OPTIMA LNB Single Slim OSLSO PLL : EAN (4260189991131) VPE 100 Stück, UVP 14,90 €
OCTAGON OPTIMA LNB Twin OTLO PLL : EAN (4260189991148) VPE 50 Stück, UVP 29,90 €
OCTAGON OPTIMA LNB Twin Slim OTLSO PLL : EAN (4260189991155) VPE 100 Stück, UVP 29,90 € ------------- the one I tested !!
OCTAGON OPTIMA LNB Quattro OQLO PLL : EAN (4260189991162) VPE 50 Stück, UVP 29,90 €
OCTAGON OPTIMA LNB Quad OQSLO PLL : EAN (4260189991179) VPE 50 Stück, UVP 39,90 €
OCTAGON OPTIMA LNB Octo OOLO PLL : EAN (4260189991186) VPE 30 Stück, UVP 59,90 €

So all Octagan lnb's have PLL

 

[radicaldoc]

On their site :



<div>OCTAGON OPTIMA LNB Single OSLO PLL : EAN (4260189991124) VPE 100 Stück, UVP 14,90 €
OCTAGON OPTIMA LNB Single Slim OSLSO PLL : EAN (4260189991131) VPE 100 Stück, UVP 14,90 €
OCTAGON OPTIMA LNB Twin OTLO PLL : EAN (4260189991148) VPE 50 Stück, UVP 29,90 €
OCTAGON OPTIMA LNB Twin Slim OTLSO PLL : EAN (4260189991155) VPE 100 Stück, UVP 29,90 € ------------- the one I tested !!
OCTAGON OPTIMA LNB Quattro OQLO PLL : EAN (4260189991162) VPE 50 Stück, UVP 29,90 €
OCTAGON OPTIMA LNB Quad OQSLO PLL : EAN (4260189991179) VPE 50 Stück, UVP 39,90 €
OCTAGON OPTIMA LNB Octo OOLO PLL : EAN (4260189991186) VPE 30 Stück, UVP 59,90 €

So all Octagan lnb's have PLL

Same as mine it cost me £15.00. I emailed Octagon about the reason nothing is said on the box about PLL Being as it was supposed to be New. And brilliant LOL
I will see what they say.

By the way when i questioned my supplier he just said No Idea no one has asked the question before and it is straight from UK supplier. Also said if i am not happy they will refund. Suppose you cannot be fairer than that......

</div>

 

[Trust]

Therefore they marked the box with 3D and 0.1dB, so silly O-no

 

[hexah]

On the other hand, some $ ky LNBs have 1.3dB max noise. O-no

 

[Channel Hopper]

The latest universal LNBs with phase lock loops are nothing like the professional LNBs from companies like Norsat and SMW.

The change from DRO to PLL technology is down to a new processor design which is a $1 chip.

The PLL stability of these is somewhere between 250 and 500kHz depending on where you read the specifications. There is also no temperature condition for the stability, meaning that the stability can vary day and night, cloud or sunny.

Whilst the chance is there that these will perform better than the standard DRO LNB universals that have been around for some ten years, the manufacturers will be doing their best to reduce costs rather than improve the technical specifications. The end result will be the majority that turn up in the shops or online will have had their technical figures 'massaged' by the importers and distributors up the food chain.

By comparison the earlier PLL technology meant a stability of between 25 and 150kHz depending on how much paid, and this figure would have been temperature independent (within reason) owing to the different technology within the casing.

 

[radicaldoc]

The latest universal LNBs with phase lock loops are nothing like the professional LNBs from companies like Norsat and SMW.

The change from DRO to PLL technology is down to a new processor design which is a $1 chip.

The PLL stability of these is somewhere between 250 and 500kHz depending on where you read the specifications. There is also no temperature condition for the stability, meaning that the stability can vary day and night, cloud or sunny.

Whilst the chance is there that these will perform better than the standard DRO LNB universals that have been around for some ten years, the manufacturers will be doing their best to reduce costs rather than improve the technical specifications. The end result will be the majority that turn up in the shops or online will have had their technical figures 'massaged' by the importers and distributors up the food chain.

By comparison the earlier PLL technology meant a stability of between 25 and 150kHz depending on how much paid, and this figure would have been temperature independent (within reason) owing to the different technology within the casing.

good reading thanks for that....

 

[archive10]

Perhaps someone can help me out on a bit of understanding. when using the c120 feed-horn with say an Invacom C120 lnb on an offset dish, is the position of the feed horn relative to the LNB critical. i.e if it is rotated does it affect the way it works?

No, it is the samme all 360 degrees around.

I see there is a specific offset LNB for use on the Channel Master 1.8 offset dishes and wondered exactly how they focus (illuminate!) to the edge of the dish – it has to differ from a prime focus feed-horn where the focus is the same for all directions but in an offset dish the focus is like looking at a slice of a PF dish from an oblique angles so I would have thought the way the focusing works on a universal feed-horn would differ quite a bit in the vertical and horizontal axes. Can someone enlighten me on how they work!

Well, it's not quite like that.

As you say, most if not all PF dishes look entirely symmetrical around the central axis.
But so do (most) offset dishes, when you look at them from the LNB.

Offset dishes such as the CM180 are NOT circular, but more approaching an oval in the vertical direction.
Technically, the shape of an offset dish is a circle projected onto a paraboloid, but with the center offset from 0 on the X axis.
(Hence the "offset".)
This allows the LNB to see a circular dish without being in the way of the incoming signals.
The dish shape is not even symmetrical around a point, the upper bit is "flatter" than then lower bit.
This is why there is a "up" direction for these dishes. (There're big letters and an arrow molded into the back!)
So even if the dish is asymetrical when looking at it directly head-on, it appears symmetrical when viewed from the offset-point of the LNB.
(see elsewhere on this site or on wikipedia for graphical illustrations of this)

Of course there are exceptions, such as the sky minidish and others that indeed look non-circular to the LNB, and therefore DO require a waveguide (feedhorn) on the LNB to be specfic to orientation. But that's a different topic.

The main difference between the PF feedhorns and the offset ones are the focal depth (roughly the "flatness" of the dish).
PF feedhorns generally to look at a wider field of view than the offset feedhorns.
So if you stick an offset LNB in a PF LNB holder, you'll only see a small part of the dish, and if the other way around you'll see way past the edges of the dish.

 

[joddle]

Thats one of the best explanations I've so far seen for feedhorns - thanks

 

[radicaldoc]

Same with mine no mention of PLL Technology I will have a word with the dealer...

The reply from Octagon..

[SIZE=12pt]Sorry[/SIZE][SIZE=12pt], there was a misunderstanding[/SIZE] about the description of the LNB. The PLL LNB models feature the following from us:

OCTAGON OPTIMA PLL LNB Single OSLO: EAN (4260189991124)
OCTAGON OPTIMA Slim Twin LNB PLL OTLSO: EAN (4260189991155)

Advantages of the PLL function: mhz 27 quarts and no frequency deviations

[SIZE=12pt]Attached you will also find photos (the photos were just photos of the boxes!)[/SIZE]

[SIZE=10pt]Für weitere Fragen stehen wir Ihnen gerne zur Verfügung.[/SIZE]

[SIZE=10pt]Mit Freundlichen Grüßen aus Murg /Kind Regards from Murg /Saygilar Sevgiler Murg´dan[/SIZE]

 

[sonnetpete]

The Octagon LNB arrived this morning so I'll be doing some tests when the weather improves (if ever LOL)...

From an initial look, the 'adjustable' length of the Octagon (I.E. fore and aft, towards or away from dish focus) is 530mm and the Black Ultra is 700mm. I think this is quite critical for fringe stuff.....you can hear my scepticism surfacing already.....However, I'll start another thread when I have some results....

 

[radicaldoc]

The Octagon LNB arrived this morning so I'll be doing some tests when the weather improves (if ever LOL)...

From an initial look, the 'adjustable' length of the Octagon (I.E. fore and aft, towards or away from dish focus) is 530mm and the Black Ultra is 700mm. I think this is quite critical for fringe stuff.....you can hear my scepticism surfacing already.....However, I'll start another thread when I have some results....

As am i as your measurements are completely different from mine My Black Ultra is 143mm between the shoulders and 150mm on the Octagon how come yours are different from mine because if these are the overall size then surly the Octagon has to be larger focal size doesn't it...? Maybe you have a different version or something to me... Mine are both pretty new.

 

[Huevos]

Hard to know what Pete is talking about. Can't think of anything that has more than half a metre of adjustment.

 

[radicaldoc]

Hard to know what Pete is talking about. Can't think of anything that has more than half a metre of adjustment.

And there is that.....!!

 

[sonnetpete]

Hard to know what Pete is talking about. Can't think of anything that has more than half a metre of adjustment.

Huevos...there are times I don't know what I'm talking about, never mind anyone else....having been brought up on feet and inches I must admit to being confused by centimetres and millimetres.....so I think what I meant was 53mm and 70mm neck length....measured from the shoulder of the LNB to the feedhorn......so the part that can be adjusted backwards and forwards.....LOL....

 

[Lazarus]

Hold up on the Pastis, mon brave!

 

[sonnetpete]

Hold up on the Pastis, mon brave!

Not that keen on Pastis actually......maybe it's a surfeit of pasties.....

 

[radicaldoc]

Huevos...there are times I don't know what I'm talking about, never mind anyone else....having been brought up on feet and inches I must admit to being confused by centimetres and millimetres.....so I think what I meant was 53mm and 70mm neck length....measured from the shoulder of the LNB to the feedhorn......so the part that can be adjusted backwards and forwards.....LOL....

I still don't see how you are getting the sizes i have just checked again as I am as bad as you my measurement are 48mm for BU you have to measure across the top because it's a curved face on it. And 54 for the Octagon this is definitely the longer of the two on mine.
I have just had this thought this is the twin Black Ultra you are measuring isn't it same as mine.. Mine are both twin's..

 

[sonnetpete]

My Black Ultra is a single, which I think has a longer neck than the twin variety. However, if you read the results I've posted in another thread, I think you'd be better off sticking with the Black Ultra.....

 

[radicaldoc]

Oh shame about that i was hoping for a comparison with BU Twin and the Octagon twin as it would appear to be different on your singles.
Which is probably why the Octagon works better on mine as the neck is longer allowing more tuning than the BU.
Looks like I will have to try and mess around with the Octagon again..
The trouble is I have to stick with twins as i wouldn't be able to record to my Humax HDR Foxsat PVR.... It would be interesting to try a single to see the difference if any here.

 

[sonnetpete]

Here are links to the Inverto pages displaying the relative dimensions of the single and the twin

http://www.inverto.tv/products/product.php?section=1&id=57

http://www.inverto.tv/products/product.php?section=1&id=68

You'll see the neck on the twin is about 2cm shorter than the single......least I think it is.....it may well be half a kilometre by my previous calculations.....

Would it not be worth experimenting with a Black Ultra single, just to see if the long neck makes a difference?.........