Norsat LNB Whats Wrong ? pics

[canofan]

Sorry about the Norsat 4708A. It is a 0.6db (4706A) you need. The 4000 are better than the 7000 in the sense that the 4000 have a noise filter needed when used close to a BUC. Otherwise same performance. Also no need for the second digit to be low for our sort of application.
You may be doing something wrong, because even with a 0.8db you ought to get better result than the Invacom.

 

[canofan]

...I am glad at your results, so you are able to watch showtime OK now ?

Sorry Keano I did not notice the question mark.
For the moment everything is ok but the weather has been fair.
I will be able to give my final appreciation when the weather gets rainy and overcast.
The reason for all this was to keep good reception during heavy rain.
Next step is to see if I could get rid of the bulky 140cm PF Triax which I use now for verticals. I should not use bigger than 120cm on the roof. I suspect that I do not need this size.

 

[canofan]

For maximum signal from the norsat lnb it should be bolted direct to the feedhorn...

The feedhorns assemblies for ChannelMaster come with a transition.
But I also saw some CM feedhorns supplied without transition.
I attached pictures of the the feedhorn/transition/lnb interfaces on my Channel Master.

A transition seems to be designed to improve VSWR, reducing by its insertion standing waves.
My feedhorn's part number is CM3040605 and has the round throat as illustrated. It is the feedhorn for a dual polarity circular feedhorn assembly. The part number should have been CM3040645.
So much for buying on Ebay.
I am amazed at the good result I got, but I assume the transition is correcting the problem partly by gradually going from round to rectangular..
If I were to use the CM3040645 will the transition still be necessary.
Please guys let me know your experience on the subject.

 

[canofan]

@ keano
Your feedhorn throat being round as illustrated in my previous post, you will need a transition.
the feedhorn which could be directly connected to the LNB has a rectangular throat WR75.
CM transitions seem to be unavailable separately.
SMW have a quarterwave transformer which does the same thing.
I have found one for Euro 29.60
_http://www.transplanet.fr/boutique/info_produit.asp?num=12782&fam=4
_http://www.hfctechnics.hu/simg/File/pdf/smw/feedhorn.pdf

 

[canofan]

....but the dual pol transition has more insertion loss than a straight connection to a single LNB. VSWR does not not necessarily have any direct relationship to insertion loss and the dual pol transition definately has insertion loss. This insertion loss will always mean that the dual pol solution will perform worse than a single pol solution alone. Insertion loss before the LNB increases the effective system noise temperature more significantly than the value of the insertion loss itself because the system noise temperature is increased disproportionately to the insertion loss itself....

I am using a feedhorn for the 11.7 to 12.2 ghz band with a Norsat 7706A and it is miracles above what I was using before.
However this feedhorn (CM3040645) has a round throat and I had to use a round to WR75 transition to make it work OK.
I cannot help thinking that, if I had a feedhorn with the same shape but with a rectangular throat (CM3040605), I could remove the transition, and its insertion loss, to achieve even better performance.
I think the transition introduces 15°K to the system noise. For Nilesat at our latitudes: a well setup antenna adds 30°K. Total noise 45°k which added to the 0.6db NF of the Norsat (45°K) is 90°k corresponding to 19.54dbk. By removing this 15°K caused by the transition we fall back to 75°K. corresponding to 18.75dbk making an improvement of 0.79db.
The difficult thing is that, when you order the longer single polarity feedhorn, you are not sure what you receive: will it be the round or the WR75 version?

 

[canofan]

I never used an OMT to combine two single band LNBs and kept wondering about the real insertion loss.
Browsing through SMWs, I was comparing the specs of the Quattro type E, LO 9.75/10.6 GHz, with the WDL type E, 9.75/10.6, GHz.
The Quattro is actually composed of two WDL type E, 9.75/10.6 GHz through an SMW OMT 30.
The Spec for the WDL type E, 9.75/10.6, GHz claims a 0.8db.NF.
The spec for the Quattro type E, LO 9.75/10.6 GHz claims a 0.9db NF.
Simple arithmetic yields the insertion loss of the OMT 30 at 0.1db.
Please comments.

 

[djgeo_gr]

good afternoon to all friends
i open again the tread` and i have some question
i have now one chanel master 3M and i am ready to set in my house i try to find the best lnb tha i can find
i read all the post and that i have to ask is where can i find and buy this lnb and working only in onee pol H or V

thanks