Just Sharing This 1.2 Precision / Octagon lnbf mod

[John]

Setting the scene .....
Iv'e had a Precision 1.2 mtr PF with it's own 1224 motor just sitting about for nearly two years doing nothing.
It's a cracking dish and should not have to suffer the indignation of it....
I'm going to use it with it's beautifully small factory designed feed / C120 flange arrangement coupled onto a recently obtained Octagon OTLSO Ku lnbf, modded to C120 flange to fit the Precision. The Octagon is very small with it's white cover on, almost invisable with it's cover off, and does not add to any signal blocking as it sits nicely behind the small Precision feed.
The C120 flange was from a faulty Ku lnbf.
The Precision will replace a CM 1.2 that is at high level on the roof..... where it was originally. The possible problem with the CM is that when it's now looking at 65 West the bottom arm is very very close to the ridge tiles and if i make a mistake with an inclination movement i could do some damage to it.
So .... thought i would have a play to see if the Octagon is any good when modded to C120 flange or not.
Just a few pics to go with the words ...

 

[moonbase]

John,

Interesting LNB modification to the feed setup on a very nice dish.

In the last photo (OCTAGON LNB MOD with Precision feed...), the Precision C120 feed that accepts the threaded studs to fix the feed support arms looks as though it has been modded. It does not look like the original Precision C120 feed illustrated in picture 2 (IMG_3433.jpg). Have you cut something off here and replaced it with something else?

Did you select the Octagon OTSLO LNB for its small footprint or it it known for its sensitivity?


Rgds

 

[John]

John,

Interesting LNB modification to the feed setup on a very nice dish.

In the last photo (OCTAGON LNB MOD with Precision feed...), the Precision C120 feed that accepts the threaded studs to fix the feed support arms looks as though it has been modded. It does not look like the original Precision C120 feed illustrated in picture 2 (IMG_3433.jpg). Have you cut something off here and replaced it with something else?

Did you select the Octagon OTSLO LNB for its small footprint or it it known for its sensitivity?


Rgds

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@moonbase ..... Well spotted my son. Thought i might have got away with that one . That is a spare feed off another Precision dish and just offered it up so as to give an idea.

Re: the Octagon, yep heard of the glowing reports about them, there not all that expensive either so worth a punt. The small footprint of it is a bonus as well.
Iv'e got a pic of the internal probes of it and the horizontal probe seems to be mis-aligned. I'm not sure if it's a deliberate factory set-up position or not for optimum performance ? but was wondering if it might give a bit of Xpol when in use ??.
Could really do with somebody else that has the same lnbf to check their probe alignments.

 

[moonbase]

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@moonbase ..... Well spotted my son. Thought i might have got away with that one . That is a spare feed off another Precision dish and just offered it up so as to give an idea...

I have not seen that version of the Precision C120 Ku feed before, the only ones I have ever come across are like the one illustrated in picture 2 (IMG_3433.jpg). At a guess it must be an older version?

 

[John]

I have not seen that version of the Precision C120 Ku feed before, the only ones I have ever come across are like the one illustrated in picture 2 (IMG_3433.jpg). At a guess it must be an older version?

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I'm not sure where it came from myself @MB ..... it might be off a 1.8 Precision. Iv'e had & collected Precision stuff over the last twenty years and struggle to remember their original source lol. The close up shot of just the feed and it's arms is the feed that came with the dish, i think it was an ex bookies (turf accountants) job.
If the rain keeps off today i'll try and get the dish / Octagon combo hooked up and see what it makes of the beacons on 65West , iv'e got an Inverto Ka/Ku on the 1.8 and a 1.2 CM on the roof dish that can see the beacons, so have two reference signal sources to compare the Octagon/Precision 1.2 with .

 

[purplemarina]

Setting the scene .....
Iv'e had a Precision 1.2 mtr PF with it's own 1224 motor just sitting about for nearly two years doing nothing.
It's a cracking dish and should not have to suffer the indignation of it....
The Precision will replace a CM 1.2 that is at high level on the roof..... where it was originally. The possible problem with the CM is that when it's now looking at 65 West the bottom arm is very very close to the ridge tiles and if i make a mistake with an inclination movement i could do some damage to it.
..

i swapped the other way precision to cm, i had the precision on a scaffold pole which flexed, (reason for changing) now the cm is on 3" pole and very solid above the gutter line, although on a bungalow. Great mod on the lnb! awaiting test results, hope there's improvement.

 

[moonbase]

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I'm not sure where it came from myself @MB ..... it might be off a 1.8 Precision. Iv'e had & collected Precision stuff over the last twenty years and struggle to remember their original source lol...

John,

Sounds familiar, I have a drawer full of Precision stuff that came from dishes ranging from 1.2m to 2.2m. All of the C120 Ku feeds I have are like the one shown in your picture of the feed with support arms attached. That picture you uploaded of the "interesting" C120 Ku feed with the Octagon LNB fitted to it is the first time I have seen that shape for a Precision C120 Ku feed.

With it attached to the dish using the feed suppoert arms, have you measured the distance of the "interesting" C120 Ku feed inner scalar rim to the dish face to see if it is located at the same length as the other C120 Ku feed that is the more common shape?

I will be interested to see how your signal levels compare and your opinion on the performance of the Octagon LNB.


Thx

 

[moonbase]

John,

I forgot to ask, is the Octagon you are using the PLL version, I think the OTLSO in the LNB name indicates it is PLL but I am not sure?

Thx

 

[John]

John,

I forgot to ask, is the Octagon you are using the PLL version, I think the OTLSO in the LNB name indicates it is PLL but I am not sure?

Thx

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It is the PLL one MB.

 

[John]

John,

Sounds familiar, I have a drawer full of Precision stuff that came from dishes ranging from 1.2m to 2.2m. All of the C120 Ku feeds I have are like the one shown in your picture of the feed with support arms attached. That picture you uploaded of the "interesting" C120 Ku feed with the Octagon LNB fitted to it is the first time I have seen that shape for a Precision C120 Ku feed.

With it attached to the dish using the feed suppoert arms, have you measured the distance of the "interesting" C120 Ku feed inner scalar rim to the dish face to see if it is located at the same length as the other C120 Ku feed that is the more common shape?

I will be interested to see how your signal levels compare and your opinion on the performance of the Octagon LNB.


Thx

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Iv'e not actually done that MB, i'll put them side to side in a comparison pic as well.
I think it might have come from the Precision 2.2 i had ????, just can't remember chap.

 

[John]

i swapped the other way precision to cm, i had the precision on a scaffold pole which flexed, (reason for changing) now the cm is on 3" pole and very solid above the gutter line, although on a bungalow. Great mod on the lnb! awaiting test results, hope there's improvement.

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Well, the Precision 1.2 was in use originally on the roof mount installation about 2-3 yrs ago and performed really well, then came the CM1.2 craze / boom so had one off Chris (Scopus) to try. After 2-3 years of use i dont think there was anything between them and any performance differences was down to using / trying different lnb's.
One of my reasons for re-installing her at the roof position is the real possibility of the CM bottom lnb arm colliding with the roof ridge tile when around at 65West.... with the Precision PF i don't have that worry.
If i get a minute i'll take a pic of it to show the possible problem.
Re: C120 mod ..... don't hold your breath too long, it might be a total flop, but as they say... No Pain-No Gain.

 

[moonbase]

Re: C120 mod ..... don't hold your breath too long, it might be a total flop, but as they say... No Pain-No Gain.

John,

Nothing ventured......

I might give this mod a go myself to see how it works out with my Unicorn 1.25m prime focus dish. It has a C120 feed that currently has an Invacom Twin LNB on it so it would be a decent test. The cuts look very clean and straight where you removed the C120 flange from the Inverto Black Pro, you have a very steady arm if you did it by hand?

Rgds

 

[John]

.... Test Bed up and ready for testing stage. Test sat at 65West is right in the middle of those tree's in the distance.

 

[moonbase]

.... Test Bed up and ready for testing stage. Test sat at 65West is right in the middle of those tree's in the distance.

John,

Flabbergasted and amazed, not with the Precision but with the mounting for the CM 1.8m, its looks an awesome piece of kit, is it hydraulically operated? It is a superb piece of UK engineering/fabrication.

 

[John]

John,

Nothing ventured......

I might give this mod a go myself to see how it works out with my Unicorn 1.25m prime focus dish. It has a C120 feed that currently has an Invacom Twin LNB on it so it would be a decent test. The cuts look very clean and straight where you removed the C120 flange from the Inverto Black Pro, you have a very steady arm if you did it by hand?

Rgds

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.. Nothing Gained. Exactly.
Another reason for me to try it is the fact that i am using the correct matched Precision feed that came on the dish and the fact that the feed position / focal point will be as Precision designed and intended it to be.
Have a go MB, see what you think.
These Octagon pll type seem to be getting a bit scarce, iv'e had to order a second one from a German site as the UK Red Apple site has sold out.

 

[John]

John,

Flabbergasted and amazed, not with the Precision but with the mounting for the CM 1.8m, its looks an awesome piece of kit, is it hydraulically operated? It is a superb piece of UK engineering/fabrication.

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Thanks ..... your cheques in the post chap.
All hand made with the bare minimum of tools, but being a contracting sparky for 50 years, fabrication became a bit of a second nature..... installing trunking, conduit, tray etc, all in the day when every set / bend / bridge etc had to be hand made ..... non of this pre-made bends etc that later came in, which i think led to the work force being less skilled eventually. A lot of the present generation of sparkies would not know or have the skills to fabricate..... sign of the times.
The structure is hand cranked to the up /down positions..... the Precision 2.2 used to be up there at one time until it got trashed with some gales a few years back

 

[moonbase]

...Have a go MB, see what you think.
These Octagon pll type seem to be getting a bit scarce, iv'e had to order a second one from a German site as the UK Red Apple site has sold out.

John,

I have been inspired by your mod and have just ordered a couple of the Octagon OTLSO LNB's from a German supplier. It made sense to order two as the postage for two was less than €1 euro more expensive than the postage for one.

Did you cut off the C120 flange from the Black Pro LNB by hand with a hacksaw/dremel?


Thx

 

[John]

John,

I have been inspired by your mod and have just ordered a couple of the Octagon OTLSO LNB's from a German supplier. It made sense to order two as the postage for two was less than €1 euro more expensive than the postage for one.

Did you cut off the C120 flange from the Black Pro LNB by hand with a hacksaw/dremel?


Thx

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Good stuff.
C120 flange cut off by large hacksaw. The trick is to accurately put a pencil mark around the barrel and then gently work your way around the barrel. You might have to do several revolutions to get the final cut through. If you can find some way of holding the lnb securely and accurately without damaging it then a single cut with a fine blade in a mechanical saw could be achieved. I had not got any devices to do the latter so i did it by hand. The barrel material is only a soft alloy and cuts pretty easily.
Note: There is a slight O/D difference between the Octagon lnbf barrel and the donor barrel/C120 flange..... just under a mil difference if i remember.

** Initial tests on the 1.2 look good but i'm running out of play time for today and there are some pretty big black rain clouds looming over.
** Observation ..... my Octagon's two output ports had a slightly higher output on one of them, noted in my notes.

 

[John]

Quote: >>** Observation ..... my Octagon's two output ports had a slightly higher output on one of them, noted in my notes.<<

This is the port with the slightly higher output, on mine at least. Will do another check when the other Octagon pll arrives.

 

[moonbase]

...Note: There is a slight O/D difference between the Octagon lnbf barrel and the donor barrel/C120 flange..... just under a mil difference if i remember...

** Observation ..... my Octagon's two output ports had a slightly higher output on one of them, noted in my notes.

John,

My next question was to be about the join between the Octagon LNB and the C120 flange harvested from the Black Pro. How did you join them, was it simply a matter of offering up one to the other and clamping them at the intersection with the O clip? Or was there a variance in the inner/outer diameters that allowed some degree of overlap? Lastly did you use any sealant/resin at the join point, ot looks like there might be some yellow sealant/resin underneath the O clip?

Re the variance in the output, could this be related to your observation that one of the LNB probes seemed slightly out of alignment? Did you notice the output level difference across the board or was it for a specific polarity or Hi/Lo band?

Thx