Marginal Satellite Signal

[brandonb959]

We have one of the big comtech dishes with a dawnco lnb feeding Dial Global/ Citadel/ Clear Channel recievers. In recent years I've noticed a decline in signal strength (low eb) and it has become somewhat of an issue. I have tried changing lnb's and peaking the dish both horizontally and vertically. I also checked the feed horn for obstructions, wasps nest, etc... On clear channel, my peak eb is about 5 and about 7 on Citadel and Dial Global, I have been told that closer to 12 is normal. There is a pine tree about 75ft from the dish with some limbs that may be possibly blocking the dish as well as woods about 200ft away, but it looks like the lnb is pointed above the tree line.

Does anybody have any thoughts? I also wonder how much difference cleaning the dish might make? It is pretty dirty.

[jammerdave]

Might also be deteriorated feedline. Worth looking at if it's more than a few years old.

df

[brandonb959]

I forgot to mention that I had already tried running a new coax just to test the old one, but had the same result. Here is what the Dish looks like and where it is pointed:

[Deep Thought]

It's been awhile since I've dealt with anything satellite besides a DirecTV dish, but that thing really looks bad. Is that tree sap on there by any chance? How rough is the surface? It may be worth a few minutes of quality time with a power washer to see if your signal levels go up with a good cleaning.

[brandonb959]

I gave the dish a nice cleaning today, but no improvement in signal strength. I guess we will resort to trimming tree limbs to see if we can increase the signal.

[PID_Stop]

I would consider replacing the feedline: the jacketing deteriorates over time, allowing moisture to penetrate the cable. Also, you might want to use RG11 if this is running terribly far -- you'll pick up about 3dB for every hundred feet of line, compared to RG6. (And if that cable is RG59... well, it should definitely be replaced!)

The other thing: take a very close look at the F connector on the LNB itself. The combination of moisure and phantom power can corrode the center fingers right off. We generally tape the living daylights out of the F connector, then seal it with Scotchkote.

-- Jeff

[brandonb959]

The run is only about 100' and I have tried running a new cable and a new lnb....

[jammerdave]

If you could find the exact center of the dish, you could pop a hole in hit, and get a "boresite" looking through the LNB to see if the tree growth is an issue. I had a similar problem a long time ago with an STL that kept deteriorating . I finally went up the tower and looked down the feed boom on the paraflector and discovered that our lone pine tree on the edge of the property had a growth spurt, and was now blocking the path. Hello, Mr. Chainsaw.. Problem solved.

df

I forgot to mention that I had already tried running a new coax just to test the old one, but had the same result. Here is what the Dish looks like and where it is pointed:

[AltheEngineer]

I have to go with the tree trim especially since the other tower is so close to the path. But I had ABC ask if I had their receiver LNB power on in addition to a different receiver and that fixed it. Even with a passive splitter that shows a power path, it can heat up some of the DC splitter pads causing an intermittant loss of signal. Dial Global usually requests a powered splitter which doesn't have that problem.

[NECRAT]

I have to go with the tree trim especially since the other tower is so close to the path. But I had ABC ask if I had their receiver LNB power on in addition to a different receiver and that fixed it. Even with a passive splitter that shows a power path, it can heat up some of the DC splitter pads causing an intermittant loss of signal. Dial Global usually requests a powered splitter which doesn't have that problem.

Al hit close to what I was going to ask. Have you checked the LNB power supply yet?
You mentioned you've swapped feedlines, and LNBs, but have you tried replacing the power supply.

Also have you looked at the Sat dish with a spectrum analyzer to see what the signal looks like ? Maybe you're experiencing some bad TI. That tower is close to the satellite path, you may be getting some TI reflecting off of it.'

Two other things to check, make sure the focus is still correct. (Distance measured from the LNB to the center of the dish. The specs for the dish will be availble from Comtech or if you have the manual), and check that the dish is still round too and not warped. (With a measuring tape, not your eyes!)

Two other notes:
1) Get that tree taken down if you can.
2) The cables "wrapped up" on the arm of the feedhorn mount should be unwrapped and run vertically with the mount itself. Don't leave those wrapped on the arm, as they will cause issues.

[Deep Thought]

OP: Wed Sep 07, 2011 3:02 pm. Zombie thread walks like zombie.

Just a reminder that it helps if when you start a topic like this that you come back and post a follow-up saying what resolved it (if anything) or that you just called in an airstrike and moved on. Otherwise people pick them up a year later and try to help solve a problem that no longer is one.

[brandonb959]

Sorry, I forgot all about this thread! I edited the pic to show that the tree in the background with an X through it was completely removed and the tree to the right of the picture had all of its limbs removed on that side. This DOUBLED our signal! Our Citadel receiver now has an Eb No of about 14 and our Clear Channel has an Eb No of between 9 and 10