Digiwave c-band lnb

[metal head]

I got a c-band lnb come today and this might seem like a stupid question but when you look in the lnb should their be something in there. It looks empty with a some little stiff wires. Thats if you look down the tube. It also came with some screws, a plastic cap with looks like it would fit the front, a hard rectangle piece of plastic about 2" by 1" and the scalar ring. Is this normal and whats the purpose of the ring and how do you adjust it. Thanks for any help.

 

[FaT Air]

some little stiff wires

are the actual antennas. They will be at 90 degrees to each other, one for each polarity. BTW- they're called "Probes" now.

a plastic cap with looks like it would fit the front

keeps the signal sucking bugs out. Yep, it goes on the front.

a hard rectangle piece of plastic about 2" by 1"

That is a "dielectric plate". It's inserted into the throat of the feed for the reception of circularly polarized satellites ONLY. These are located way out east over the Atlantic ocean. Not needed for any CONUS located satellites.

whats the purpose of the (scalar)ring

To focus the "view of the feed" to not extend past the dish surface, This reduces the local "terrestrial interference".

and how do you adjust it

Here I will refer you to page 3 of the BUD Manual to calculate the f/D ratio. Most feeds require the f/D number, or corresponding line, imprinted/molded into the side of the feed, be aligned with the backside(smooth) side of the scalar ring. Check the mfgr's data sheet to confirm, (The side of the ring with the grooves faces the dish) Some have found that some experimentation, deviating from the calculated focal length and the f/D setting, can improve performance. Your mileage may vary.

Is this normal(?)

Welcome to C band. There's a lot of FTA here. BTW- I think that LNBF is the same as, or is a relabeled, DMX241, which I use. The numbers on the backside are the SKEW. With the scalar ring/feed installed on the dish, the 0 (zero) should point to the east horizon, with the dish at Zenith, when the dish is installed on a polar mount. Adjusted CW or CCW as necessary if on an Az-El mount.

 

[metal head]

WOW, thanks for the reply. Is the scaler adjustment important for finding the signal.

 

[FaT Air]

Not as important as the focal length, but important enough for maximum performance. The calculated focal length should get you a signal. Then adjust the focal length for max, remeasure the focal length and recalculate the f/D an move the scalar, keeping the feed at the same focal length. This may require some mechanical modification of the support.