signal Loss with Long Cable

[rafikmw]

Dear All,

I have a 3 satellite dish
1 Diseqc (4x1)

here's my problem: one of the dishes is mounted on the building beside me, the cable is more than 100 meters long (around 300 feet or more)
all cable are connected to the diseqc which is on the roof next to the other 2 dishes (on my building).

I have a dreambox receiver, I'm getting very good quality and signals for the 2 receivers on my building but for the one which has more than 100 meters long cable it's a mess, I'm getting some channels and some the signal could not be found. Even within the same bouquet, I don't understand why that is happening. I bought an inline amp from radioshack last night and wondering if it will help, also if you agree that it would, where should I install it?

thank you

p.s: I forgot to mention that the LNB has 2 outputs if that makes any changes

 

[Van]

This question should be moved to the fta section where it can be answered.

 

[walrus1957]

Dear All,

I have a 3 satellite dish
1 Diseqc (4x1)

here's my problem: one of the dishes is mounted on the building beside me, the cable is more than 100 meters long (around 300 feet or more)
all cable are connected to the diseqc which is on the roof next to the other 2 dishes (on my building).

I have a dreambox receiver, I'm getting very good quality and signals for the 2 receivers on my building but for the one which has more than 100 meters long cable it's a mess, I'm getting some channels and some the signal could not be found. Even within the same bouquet, I don't understand why that is happening. I bought an inline amp from radioshack last night and wondering if it will help, also if you agree that it would, where should I install it?

thank you

p.s: I forgot to mention that the LNB has 2 outputs if that makes any changes

If I understand you correctly, the dish that is connected to the 100 meter cable will get some channels but no signal at all from others. I beleive the long coax run has a fair amount of voltage drop. By the time you do a DC voltage level shift at the receiver end it isn't sufficient to change the LNB internal switch from H to V, or V to H polarization. If I recall correctly and if you are not using a 22khz switch for changing polarity, most LNBs switch using DC levels 13 and 18 volts. If this be the case I do not believe the line amp will do you any good. Best you could do is use a quality coax that has the lowest DC line lose, shorten the cable anywhere you can, and make sure you have clean/tight quality connectors on the ends. 100 meters of cable is really pushing it.

Can you test the channels and determine if your missing one polarity or the other?

 

[AcWxRadar]

If I understand you correctly, the dish that is connected to the 100 meter cable will get some channels but no signal at all from others. I beleive the long coax run has a fair amount of voltage drop. By the time you do a DC voltage level shift at the receiver end it isn't sufficient to change the LNB internal switch from H to V, or V to H polarization. If I recall correctly and if you are not using a 22khz switch for changing polarity, most LNBs switch using DC levels 13 and 18 volts. If this be the case I do not believe the line amp will do you any good. Best you could do is use a quality coax that has the lowest DC line lose, shorten the cable anywhere you can, and make sure you have clean/tight quality connectors on the ends. 100 meters of cable is really pushing it.

Can you test the channels and determine if your missing one polarity or the other?

Good morning Walrus!

I have the same opinion here. 100M or better than 300 feet is a really long cable run and Rafikmw should probably be considering RG11 instead of RG6 cable.

You recall our test at my house with 183 feet of RG6 plus maybe 20-25 feet or so of indoor cabling. That worked, controlled the motor and the LNBF, but it was definitely apparent that there were DC line losses over that distance. The signal quality didn't suffer, but the signal level did. Rafikmw has an additional 100 feet more than this and I bet that this is just too much.

Radar

 

[Sadie]

300ft of cable is pushing the limit, it may work OK with good cable, I'm running 220 ft with cheap RG6 cable.
If your not experiencing significant DC line losses with problems switching between horizontal and vertical as mentioned by Walrus1957 the line amp may help.
I would try installing the line amp after about 200ft of cable. Do not install it close to the dish since the powerful signal from the LNB will likely overload the line amp resulting in distortion that could actually result in a lower signal quality. On the other hand if you install it too far away from the LNB the line amp will not see any useful signal to amplify just noise and that is all that will be amplified.
Line amps are designed to compensate for line signal losses and are likely to be no more sensitive to signal than your receiver so it makes no sense having it close to the receiver.
The are few installations were they make any sense, yours may be one of them but it needs to be installed at a point in the cable where the although the signal is reduced it is perfectly usable to your receiver at that point, it will then boost the signal by what ever its gain rating is to allow an additional length of cable. (simplified explanation leaving out dynamic range capabilities of receiver and amp)

 

[pedrogarcia]

Rafikmw
If I were you I would look to the proper solution. Relocate the long distance dish onto your building even if it means buying a new dish (if you are sharing). Good R11 cable and line amps are an expensive compromise without guarantees

 

[Sadoun]

Good advice from above members.

Also, you may want to consider putting a motor on one of the dishes.