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FridgeFTA has decided that its finally time to put some claims to the test when it comes to DMS vs WSI LNBFs. Are WSI’s clones? Which LNBF is built better? Which one performs better?

We’ve had a “trade in” program to acquire some WSI products for testing against DMS products. The DMX242 was the first to arrive and I have just completed evaluation and testing on the DMX242 and the DMS BSC422.

Both LNBFs are slightly used and are in good working condition. The DMS BSC422 was probably one of the first available here in North America. I pulled it out of FridgeFTA stock with the first shipment and have used it for testing, evaluation and development work on the C-band on the small dish project. The WSI DMX242 was used by its owner on both the C-band small dish project and on a BUD.

Test1: Visual Inspection and Quality

I pulled the WSI DMX242 out of the box. Outward appearance wise it is a dead ringer for the DMS BSC422. This was no surprise as many WSI LNBFs are clones of DMS products. DMS BSC421 > WSI DMX241 ; DMS BSC621 > WSI DMX741 are two examples.

Next I examined the DMS BSC422 with the WSI DMX242. On a casual inspection the only difference appeared to be the label. I use all 6500k “daylighers” here that produce very white light. Looking carefully I could see that the WSI DMX242 is painted a bit of a brighter white than the DMS BSC422, but the colors are very close.

With a bit of further examination I noted that the numbering and markings such as the skew marks and scale for positioning were much less readable on the DMS LNBF. First glance looked like the stampings into the LNBF were less sharp and not as deep as the WSI LNBF. I nearly called WSI as the winner on this point until I looked even closer. As it turns out the paint on the DMS LNBF is thicker and is a higher quality paint/finish than what is on the WSI. I determined this by inspecting the focal scale numbers on the side of each feedhorn. The DMS is less readable because of the thicker paint filling in the stampings. The DMX actually has metal visible where the paint in and around the stampings is thinner.

So aside from the slight color difference the WSI definitely uses cheaper and thinner paint. Because of this the WSI will be less corrosion resistant.

Winner: DMS BSC422

Test 2: Feedhorn Construction

Since visually the two LNBFs appear to be almost identical I got out the micrometer and checked both LNBFs. For anyone that doesn’t know a micrometer is a device used to measure thickness down to less than .001 inches.

First check was of the feedhorn wall thickness. I tested 3 points near the throat of each LNBF, same spots on each one.

DMS BSC422 – .070 ; .074 ; .071. Average wall thickness: .0717

WSI DMX242 – .063 ; .059 ; .062. Average wall thickness: .0613

The DMS at its thinnest point is heavier than the WSI at its thickest. The average difference is .0104. The DMS LNBF has 17% thicker feedhorn walls.

Why does this matter? Because you are using bolts to press a scalar ring against the LNBF walls. In the case of a LNBF mounted on a prime focus C-band dish this also holds the LNBF in place. The thinner LNBF will flex more and will crush and distort easier.

Winner: DMS BSC422

Test 3: LNB Internals Visual Inspection

Next I removed the covers from each LNB and examined the insides. Each cover is secured with 4 screws and has a weatherproof rubber seal set into a groove on the LNB housing. The DMS seal remained positioned in the LNB groove. The WSI seal came out with the cover, making it harder to re-seal properly.

One thing was immediately obvious inside the WSI DMX242: there appears to have been a manufacturing problem with it. An examination of the cover makes it very obvious that the “foam” pad had been stuck in one position and then removed and re-positioned. The pad within the LNB on the WSI also has a hole or tear in it. Finally, the WSI pad positioning is crooked and the two pads do not line up properly. None of this was an issue with the DMS internals, everything appears to have been done right the first time, alignment appears good, and there is no hole or tear in the DMS pad.

Both LNBFs use what appears to be identical electronics from the PCB to each IC. NEC electronics appear to be present on each board. Because PCB’s and electronics are so easy to make a decent clone of I cannot tell if the WSI is a clone of the DMS board or the identical board sourced from the same place. See the current tests later in the article for further results.

Winner: DMS BSC422

Test 4: Real World Fringe Signal Testing

So how do the two LNBFs perform? For this test I used the C-band on a small dish project setup on a HOTDISH90 and the Traxis DBS4000 to gather numbers. Both tests were conducted within 20 minutes with the sun out and mid 70’s temperature.

The same scalar and LNBF bracket was used for both LNBFs. No tuning was done for either setup to ensure identical testing parameters. Each setup was done inside on the bench as follows:

A solid piece of cardboard was securely taped within the deepest scalar ring. Each LNBF was inserted into the scalar, rested flat on the cardboard. Skew was set to the “top” scalar bolt (this scalar has drain holes at the “bottom” and the LNBF was secured with even pressure in the center of the scalar. The cardboard was then removed and the assembly checked for straightness. The LNBF bracket was aligned with the “top” scalar bolt and was installed up against the back of the scalar ring.

This certainly is not the ideal position for the C-band project but provided a simple and identical setup between the two LNBFs.

Testing was performed using the CW transponder on Galaxy 17/91W. This setup provided a fringe signal level to evaluate stability and quality levels. With the C-band small dish project almost any difference between the two LNBFs would be apparent, especially on a fringe signal.

Both the quality meter and the picture output was watched for about 5 minutes with each LNBF.

DMS BSC422
Quality varied between 49 – 55, a 6 point range, with 52 being typical. The mathematical average is 52. Some minor pixilation occurred near the lower readings.

WSI DMX242
Quality varied between 46 – 52, a 6 point range, with 49 being typical. The mathematical average is 49. Pixilation severity and overall pixilation time was higher than the DMS LNBF.

Both LNBFs produced a stable Signal reading of 87% on the Traxis. The DMS LNBF was +3 quality level over the WSI.

Winner: DMS BSC422

65dB vs 70dB Gain

DMS advertises the BSC422 as having a typical 65dB gain. WSI advertises the DMX242 as simply having a 70dB gain. WSI seems to rate all their C-band LNBFs as being 5dB above the DMS product.

There are many ways to rate gain, each depends on what conditions were used and what scale is being used. “Typical” would be like the norm or average. As WSI does not state if their rating is typical or maximum or something else I cannot explain what the 70dB is supposed to mean. If this is a maximum rating under ideal conditions it is a meaningless number.

Based on testing and marketing one may draw some conclusions about the gain ratings. Both LNBs appear to use identical circuitry, so how would the WSI have a higher LNB gain over the DMS?

The WSI also performed worse on the fringe test. If the WSI LNB somehow did have a superior gain it is not apparent in real world performance. From speaking with a LNBF engineer I have learned that the signal reading on a receiver can be made to go up by jacking up the LNB gain. If the gain was really higher on the WSI, why did the signal under identical conditions exactly match the DMS?

A final, and more likely scenario that explains the higher rating for the WSI is marketing. Each C-band LNB from WSI mysteriously has a higher gain than the DMS product, I believe in all cases by the 5dB. Stamping a higher number on the LNB would make some customers believe it is a better product.

In any case, realistically we can say that there is no higher gain on the WSI LNB.

Test 5: Current Test

Each LNBF was tested with a digital multimeter inline at the receiver while the LNBF was on the dish. Each was tuned to the same polarity. As the DMM does not pass the I.F. frequencies, no actual picture was being watched or received in the test.

I believe that when a manufacturer rates LNBF current they do so on the horizontal (18V) polarity because it produces a lower corresponding current, i.e. Ohm’s Law. Vertical (13V) therefore increases the current consumption and gives you more of a maximum value. For this reason, the test was conducted using vertical polarity.

DMS BSC422
167.7mA – 168.1mA. Average: 167.9mA Range: 0.4mA.

WSI DMX242
174.8mA – 175.3mA. Average: 175.05mA. Range: 0.5mA.

The current test makes it obvious that the DMS LNB is more efficient than the WSI. It is also slightly more stable as current consumption fluctuates a little less.

Based on the current test and the quality level results it is likely that the WSI circuitry is a clone rather than the identical circuitry from the DMS LNB.

Winner: DMS BSC422

Conclusions

Based on examination of both the outside and insides of the LNBFs it is obvious that the WSI is a clone. Further, based on the thinner feedhorn walls, cheaper & thinner paint, the discovered manufacturing error and torn pad inside the WSI and the higher current consumption of the “identical” board, it is a cheap clone.

Visually to the average user the WSI would look the same. The deceptive use of “dyslexic” numbering on the WSI (242 > 422) further reinforces this. Finally, DMX sounds very close to DMS especially when you say the two outloud.

Performance wise the DMS is the better product both in current consumption and real world quality levels. The lower current consumption of the DMS combined with the higher quality level performance shows the DMS BSC422 to be the better LNBF.

However, the WSI DMX242 does work. It did produce a picture, even though more pixilated. I would expect with strong signals that the WSI would perform similarly to the DMS for picture stability and quality level. Most every LNBF will perform fine on strong signals, it is weak and fringe signals where the quality difference becomes apparent.