So, what's inside an LNB?

lhousesoccer

Member
Original poster
Jun 13, 2005
14
1
I'm up on the roof of my 2-story Cape-style house the other day, sitting on the peak by one gable end, mounting a new 60cm elliptical dish to a mast I have up there.

The LNB is an XKU 4 port LNB. I thought I had the LNB tightened into the arm with a screw, but apparently not. It slipped out, went sliding down the roof, and shot off the 2nd story gutter, landing on the lawn.

Externally, it looks fine. Just some grass stains. But I'm worried about what might have happened internally. I don't know what's inside that that might have broken.

After retrieving the LNB and getting everything hooked up, I started trying to aim the dish manually (no sat finder). I'm having difficultly currently getting a strong signal (haven't activated the receiver yet), but the square in front of the signal strength meter on the on-screen signal strength setup menu (ARRIS HDDSR600) only shows red. The self-installation manual from Shaw says it should be green.

That COULD be because I'm currently shooting into 4 large trees which should be cut down by the weekend. I'm hoping the square turns green after that and I can lock onto the satellites, but in the back of my mind I'm wondering if the crash to the ground of the LNB messed something up.

Any thoughts?
 
That's a HELL of a shock to the electronics inside the lnb. Basically, there's an antenna probe, followed by a super high-gain amplifier. Probably all surface mount nowadays, so you very well could have broken it. Is it now scratched up at all?

Did you buy the dish an lnb outright, or did it come as part of a self-install kit?

Could be the lnb was DOA right from the start, as far as you know...
 
Insiide a Ku LNB are two tiny pin-like antennas, one for vertical, one for horizontal, followed by a waveguide (kinda' looks like a maze), then circuitry to down-convert and amplify the signal. Have taken a few apart just to see what the innards looked like.
 
try channel 350 or 700. They are the strongest and best for tuning in a dish and both work on either type lnb.
 
OK, so I swapped out the old coax cable (25 years old) and ran 50-ft of new RG-6. The square in front of the signal meter is now green (yeah!), but I'm getting 0% signal strength. I've lined up the satellite at the compass heading and elevation required based on a couple online sat finders for my position. I've moved it incrementally back and forth. I had one moment where the signal meter filled green and jumped up to nearly 100% but that last about 1 second then back down to zero. So, I'm wondering if I have a bad XKu Quad LNB. Is that possible? One thing I failed to mention before is that the LNB actually fell off the antenna arm (screw wasn't tight) and slid down the roof and landing on the lawn. About a 15 foot fall from the edge of the roof to the ground. Could this have broken it completely? Also, should it matter what connection port I screw the RG-6 coax into on the LNB?

I'll try 350 and 700 and see what happens.

Thanks everyone.
 
No luck with 350 of 700. The receiver won't let me tune to those channels. This is a brand new receiver from Best Buy and it's never been activated. I'm just doing the initial setup and alignment, which you're supposed to be able to do BEFORE you activate it. I'm on channel 252, as per the manual.
 
Last edited:
I have upgraded to the Triple xKu LNB and it was damaged by a falling branch. I was wondering if I purchase another LNB of the same kind if it needs to be activated like when I upgraded or will it work after installing it.

cheers
 

Users Who Are Viewing This Thread (Total: 0, Members: 0, Guests: 0)

Who Read This Thread (Total Members: 1)