DMX741 C/Ku LNBF Improvement

[1ADAM12]

Minimo had posted this improvement for his 6' PF dish. I wanted to see if it would work on a 1.2m offset dish.

Buy adding a spacer between the C and Ku section I was able to log additional TP's that I had trouble with before.

Example- AMC9 RTV before nill after 68%SQ.

It is great to have C and Ku on the same dish without offset lnbf's. However, this improvement is marginal by comparison to offset lnbf.

 

[Babadem]

Minimo had posted this improvement for his 6' PF dish. I wanted to see if it would work on a 1.2m offset dish.

Buy adding a spacer between the C and Ku section I was able to log additional TP's that I had trouble with before.

Example- AMC9 RTV before nill after 68%SQ.

It is great to have C and Ku on the same dish without offset lnbf's. However, this improvement is marginal by comparison to offset lnbf.

Very nice!!!!!!:up What size is the spacer?

 

[nycrich]

I use this lnb on my prime focus getting C/Ku on a 6 ft with good results, but good work doing the mod. I might try it on my 6 ft Andrew Offset as soon as I could figure out the 4.5 in mount needed!!

 

[pro96]

Mod or no mod, the KU side still bad on 6ft or under while u have the c-band locked.

 

[McGuyver]

I recall reading that it was a 1" spacer although I wonder if it may differ for dish size and type

 

[starman345]

If you pull the plastic throat cover off you will get even more signal.

 

[1ADAM12]

Spacer Length

I recall reading that it was a 1" spacer although I wonder if it may differ for dish size and type

I used 1/2" but you maybe right about dish factor.

Very nice!!!!!!:up What size is the spacer?

You can get details by searching Minimo posts.

 

[McGuyver]

Hey 1ADAM12, my memory doesn't always serve me correctly and maybe it was 1/2" I read and as I think about it, the dish types, size and I suppose the F/D could have an effect, it would be interesting to have a series of selective lengths to test for optimum Ku QS.

Question: after the Ku mod, did you note any variance in the C signal or did it remain the same? I wonder if the change of back end reflection has any effect on the C sigs if at all it has any effect., just pondering the thought is all.

 

[1ADAM12]

Setup Procedure

Question: after the Ku mod, did you note any variance in the C signal or did it remain the same? I wonder if the change of back end reflection has any effect on the C sigs if at all it has any effect., just pondering the thought is all.

With spacer and the flat Scalar set onto the lnbf just as shown, 1/8" setback, on a GeoSatPro 1.2 meter offset, the C/Ku focal points are together. The focal length measures 30 5/8" from the center of the dish between the four bolts and the plastic lens cap.

The setup uses the WSI lnbf holder, the SatAV holder is too difficult to use, the lnbf binds in the holder.

The setup procedure is to set the Scalar first then run the lnbf back until the Ku is peaked. C band is so broad in tune range it no longer is an issue.

I'm very happy with the setup. I get 87% SQ on C band 91W, 89W, 95W watchable signal on 99W. Ku is mostly above 80% except for RTV which varies between 70% and 87% SQ. Using CS6000P receiver.

The WSI conical Scalar didn't work for this setup.

Adam

 

[McGuyver]

The setup procedure is to set the Scalar first then run the lnbf back until the Ku is peaked.

Did you use a F/D calculator to determine the scalar position or ???
I remember reading about this in another thread but can't recall the details or where that thread is.

 

[1ADAM12]

Set Scalar DMX 741 lnbf

Did you use a F/D calculator to determine the scalar position or ???/QUOTE]

Dreamfox1 was the first to report the 1/8" Scalar setback. Walrus 1957 also reported this finding. Experimentation was likely the method. Works for me. This applies to 1m or 1.2 m offset dish. Don't know about other dishes.

Adam