My dishes collection

[RimaNTSS]

Someone already try to remove properly the fibo feedhorn platic cap ? Is there a way to change it ?

I think it is not easy to remove the cap, and even more difficult to place it back. Most likely, after you remove the metal ring, it will be broken. It, probably, can be replaced by another one, but some kind of special tool will be needed. BTW, one of the Fibo feedhorns I have come with a removable plastic cap. I also have another one, exactly the same but different color, which I do not remember where it comes from. But, I feel those caps are special for satellite LNBs, so should not steal a lot of signal. If you decide to remove the cap and have difficulties installing it back, I could give you one of mine.

 

[AtOM13]

Ok ! For the moment I will not touch this cap ... for the moment

 

[RimaNTSS]

For the moment I will not touch this cap

I am pretty sure that the temporary (nothing can be more permanent) solution like this can provide you better performance than the original Fibo feedhorn cap.

 

[AtOM13]

That's a good idea ! I also find another cap in the same size ... but maybe steal a bit of signal

 

[AtOM13]

Fibotization in progress !
Just enough time to tested today with lnverto Black ultra c120. Only 1% SQ more on 4.8e than original setup.
I quickly look on others satellites, SNR was worst than original setup ... need some adjustments

 

[John]

That's a good idea ! I also find another cap in the same size ... but maybe steal a bit of signal
View attachment 157715

Re: lnb caps , there could be around 1/2 a dB or so lost through some caps, not a problem if your only looking at strong satellite signals but very important if your a Dx'er.
If i try out any new material for an lnb cap I always give it a microwave oven test ... ie 15 to 20 seconds or so , feel or test material for a temparature guide, remove after zapping it and it should be the same temp coming out. If it shows a rise in temp then it has absorbed RF which is what you don't want especially if it's an lnb cap looking at a DX signal.
I'm using RF transparent film over my Ka and Cband lnb's on the 2.2mtr, still have to change the Ku lnb cap though.
CCTV camera shot of caps.

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[AtOM13]

Wow impressive setup ! You have installed an LNB changer ?
RF plastic film can be a good option, you must change it frequently ?

 

[John]

Wow impressive setup ! You have installed an LNB changer ?
RF plastic film can be a good option, you must change it frequently ?

I use an lnb changer on my 1.2 Gibby for various Ka band lnb's and also an Extended Ku lnbf.
Also got a changer on my 2.2m PF for Cband / Ext Cband/ Ku/ Ka band D.
A Very useful device.

 

[AtOM13]

Yesterday, I've made some test but performance still similar to my 1m dish ! Not normal... maybe this Inverto IBU flanged LNB is in cause
Dur-line lnb will probably do a better job but need to cut just a little bit

 

[AtOM13]

Still testing yesterday...
Try with new Dur-line LNB modified for fibo feedhorn, just 1%SQ more.
I still have no more gain with Fibo setup
Here's a picture with LNB at best position with Fibo setup... I have to measure but focal point seems to close from the dish

 

[RimaNTSS]

at best position with Fibo setup.

Did you also measure the leaning of the dish at this point? If the leaning is not correct, then the position of the LNB will be different.

 

[RimaNTSS]

If your due-south satellite is ex. Sirius (Astra4 @4.8*E) with elevation 39.4* then the leaning of the dish must be (39.4-22.6) 16.8*. If it is not 16.8 then the position of the LNB is wrong.

 

[AtOM13]

I'm sorry @RimaNTSS but I don't know what is the leaning of the dish ?
According to your picture, focal point of the LNB to "A" point is 119cm.

 

[RimaNTSS]

the leaning of the dish ?

By leaning, I mean the angle between vertical and the face of the dish. On the picture is the angle between 2 red lines.

 

[AtOM13]

Ok I'll check that this morning, thanks!
But for the moment sub focus seems a bit far from the focal point like you can see in this picture

 

[RimaNTSS]

You have all the adjustment possibilities in your setup. I think the easiest way for you to perfectly adjust the antenna would be: point the antenna directly south, towards Astra4, make sure the antenna is leaned backwards 16.8 degrees and then find the position of the feed when signal strength has maximum strength. Choose the weakest transponder, if possible.

 

[AtOM13]

Seems not so bad ?

 

[RimaNTSS]

Seems not so bad ?

If in one word then it is "good", but, in two words, "not good" You are almost 1* away! Correct the leaning and then position the feed for optimal signal value.

 

[AtOM13]

Ok, lean is corrected.
Still at 80% SQ on 4.8e with the weakest frequency ( 11747 V ) without Fibo.
Haven't time to check performance with Fibo, but I take another picture with Fibo Sub and feedhorn, LNB focal point is 14cm from the middle of the sub

 

[RimaNTSS]

LNB focal point is 14cm from the middle of the sub

What do you mean by that? Can you draw it on the picture?