Thread: Test, Comparison, and Review WS International DMX741 C/Ku LNBF

The Test:

The test was performed on my 10 foot perforated Unimesh Scanning/Testing Dish mounted on an AJAK H-H 180 mount using my tried and tested Pansat 3500SD. I ran a base set of numbers using my ADL patent infringing CoRotor (special Ku probe), a Chaparral 20K old style (built-in elbow) C-Band LNB, and an NJR .7db PLL Ku LNB. I chose a random set of satellites and transponders from the far West to the far East of my viewable arc. I next installed a Geosat Pro CK-1 (closest real apples to apples competitor of the DMX741) and ran the numbers on the same satellites and transponders across the arc. Finally, I installed the WS International DMX741 and ran the numbers on it.

Please keep in mind that the test was not all run on the same day. I started with the CoRotor and CK-1 on last Saturday, but due to circumstances beyond my control, I couldn't finish the test until today. Also keep in mind that I didn't spend my usual several hours tuning in the two LNBFs. The dish was already set, and I did make some adjustments to center, skew, and focal length. I also took advantage of the Chaparral scaler rather than re-doing the whole dish setup. To get maximum numbers, you need to spend some time with LNBFs. They are different than Co-Rotors and everything must be set perfectly to get best performance. I am sure I could get better numbers on both LNBFs in quesion if I were to spend a bit more time "fine tuning".

The Numbers Comparison:

Numbers on different receivers will yield different results depending on the receiver, but here they are as I recorded them.

Equipment------------------------------CoRotor-----------CK-1----------DMX741
131W - C 3747 H California Channel-------90%----------------75%---------------90%
129W - Ku 11963 H WSTV----------------89%----------------75%---------------90%
123W - Ku 11720 V WNGS----------------75%----------------45%---------------60%
101W - Ku 11856 H - AOC----------------60%-----------------45%---------------45%
95W - C 4041 H - Daystar----------------90%----------------89%---------------80%
91W - Ku 12050 V - test card------------75%----------------45%---------------45%
91W - C 3720 H - The CW---------------99%----------------99%---------------99%
83W - Ku 11735 H - RTN-----------------70%----------------45%---------------30%
72W - Ku 12053 V - NBC-----------------90%----------------90%---------------60%
72W - C 4040 V - NASA-------------------99%----------------90%---------------90%
43W - C 4152 H - Rural-------------------60%---------------45%---------------45%
30W - Ku 11883 V - Cubavision------------75%----------------45%---------------80%

The Review:

The DMX741 is a well designed C/Ku LNBF with a straight barrel shaped feed-horn. It fits very snugly into my Chaparral scaler which I like. The raised numbers were of no use to me because I had to grind them off to get it to fit inside my ancient scaler. It fits into it's oem scaler without having to "make it fit". In my opinion it is a little too loose in it's own scaler. The Co-Rotor II scaler has protrusions in the inside circle which allow it to fit in and can rotate the numbers past the protrusions without having to grind the numbers off. It could cause problems if that were the critical point of the skew.

The numbers above pretty much tell the tale and you can see for yourself. I have had the CK-1 for some time and have always liked it's performance and would have to say the DMX741 is equally as good a performer plus easier to install on the dish with the straight barrel feed-horn.

Pros:
Straight barrel feed-horn design
F/D numbers
Skew adjustment numbers
Great Performance on C-Band and Ku Band



Cons:
F/D numbers would be better recessed
Scaler could be a little snugger (goes with raised numbers)

All in all, it is a great addition to our choices for modern voltage controlled C/Ku LNBFs!!

I would encourage others who own this product to post their findings here as well.

Very Nice Linuxman!

Nice review, linuxman, appreciated!

How does the CK-1 fit in a Chapparal scalar, compared to the DMX741 ?

Very thought-provoking! - - Thanks for the fine review.
Hope others run some comparison tests, too.
Like to see what a dozen DMX's do up against a random dozen other LNBFs.
More data is always more better.

Apparently these don't suffer from the Ku misalignment recently reported by some of the -621's.
Guess that was never a problem on the Ck-1's.

Hope the members test-driving the DMX's will ALSO give these a week or two and report back on long-term reliability, temperature drift (if detected), and saturation on hot birds.
There's nothing like living with one to find the little secrets.

Great news -

Biggest improvement for me, is that the LPBS DVB-S2 feeds holds after the sun goes down.
Otherwise, I saw about an 8% overall Ku improvement.

Originally Posted by Lak7

Biggest improvement for me, is that the LPBS DVB-S2 feeds holds after the sun goes down.

Well... that's a make-it or break-it decision!
Kinda like getting a bigger dish to combat rain fade, huh?

Originally Posted by Lak7

Otherwise, I saw about an 8% overall Ku improvement.

Great news... but over what? -

Originally Posted by phlatwound

Nice review, linuxman, appreciated!

How does the CK-1 fit in a Chapparal scalar, compared to the DMX741 ?

Thanks!

The CK-1 has a slightly tapered feed-horn barrel which fits a little loose even in it's own scalar and very loose in the Chaparral scalar.

Thanks for taking the time to post your review!

Do you think it is safe to assume a good co-rotor install will always beat these new products? Or do you think the data favors the co-rotor because the installation was optimized for it? Did all three products yield acceptable results from a picture quality perspective with your receiver?

Thanks again....

Originally Posted by Zorak

Thanks for taking the time to post your review!

Do you think it is safe to assume a good co-rotor install will always beat these new products? Or do you think the data favors the co-rotor because the installation was optimized for it? Did all three products yield acceptable results from a picture quality perspective with your receiver?

Thanks again....

I was hoping one of the engineer types might answer your questions with a better response than I can give, but here goes.

The difference in design between the Co-Rotor and these new voltage controlled LNBFs is what makes the performance higher with the Co-Rotors. There is the obvious difference with adjustable skew, but beyond that, the probes are located in different places.

The evidence over the past couple of years have indicated that C-Band has not been a problem, and the products above indicate that very high results can be expected on C-Band with the newer LNBFs.

The problem arises with Ku Band. I have never owned a BSC621, but have read where the Ku performance was unsatisfactory. Both the products tested above show a pretty decent Ku performance.

So in my opinion, these newer products have come a long way towards filling a need in our hobby.

As the products are used, and more data is gathered, I think the manufacturers will continue to improve their products and the next generation will be even better. At least I hope so.

As far as picture quality, as long as the signal quality meets the threshold on your receiver, the picture quality is the same.

If others have answers, please put in your two cents worth.