Satellite dish amplifier

[jyfeng]

Hi,

I want to amplify the weak satellite signal I receive. Is it OK to use an amplifier? Will the power HH motor still work?

thanks,


Jeffrey

[pictureon]

Motor should work fine

[rainman]

using a amplifier should work just fine.

[elgemcdlf]

Amp should be placed as close to the lnbf as possible. I run one on each of my lnbf's / lnb's that run to my DVB receiver. The run to the 4DTV is short enough it does not really need any.

[wejones]

Just a few opinions on signal amplifiers.

I've never really seen a situation where an amplifier helped much, although I THINK that whether it has a chance to help depends on where you put the amplifier, and on just WHY the signal is weak.

Amplifiers DO help if you have a weak signal at the antenna. In that situation, you want to put the amplifier out very close to the antenna (dish). However in these sat systems, you already HAVE an amplifier out at the dish, it is in your LNBF. A sat signal after the LNBF is NOT a weak signal situation. It really doesn't help much if any, and actually can make things worse if it is a poor quality amplifier, to put a second amplifier out at the dish. The only reason I can see that an amplifier out at the dish will help, is if the LNBF doesn't have much gain, and the only reason I see that this might happen is that LNBF manufacturers might be cutting back on gain to make their noise figure look better.

Similarly, and worse, it does almost no good to put an amplifier inside the house next to the receiver. Again, you already have an amplifier in your receiver. The reason that it doesn't help much, as with the situation of the amp out at the dish, is that you end up amplifying noise more than signal, and with a sat receiver, signal to noise ratio is more important than signal level. By the time the signal is in at the receiver, you have even more noise to amplify.

I say it depends on WHY the signal is weak, and where you put the amplifier, is because if your signal is weak because of a long feed line, then what you have is a situation where both signal and noise are strong out at the dish, but are both attenuated along the feed line. However there is also going to be a little additional noise introduced along the way. If you wait and try to put your amplifier in the house, it is too late, because too much noise has been introduced by that point. In my opinion, and this is purely opinion, as I have not tried this, I THINK that the best way to use an amplifier to compensate for a long feedline run, is to put the amplifier mid-way between the dish and the receiver. What I think is that once the signal and noise are attenuated a bit by the trip down the feed line, amplification can help to bring it back up to the level it was at back at the dish. However this can also be problematic too, because this provides an entry point for more noise, and also moisture, etc. When you talk about long feedline runs, we're talking close to 300', because I haven't noticed any signal degradation from runs in the 200-250' range that would be helped by amplification, however once you get that long of a run, I really think you're going to run into other problems, particularly with the DC voltage that runs your LNBF and/or motor. I'm actually amazed that I can still get the lnbf to switch between H/V after more than 200' of feed line, because I'm sure surprised that the 18V wouldn't be down close to 13V by the time it gets out to the LNBF, however I don't seem to be having a problem.

The only other place that I think an amplifier MIGHT help, is very near a splitter. I have NOT tried this as yet. The reason I think it MIGHT help, is that a splitter cuts your signal about in half, and I'd think that it would also cut your noise in half too, so if you put your amp their, it seems like there would be a chance that you could bring the signal back up without adversely affecting the S/N ratio.

Anyway, there are a lot of reasons why using an amplifier isn't likely to solve the low signal problem, however on the other hand, it doesn't hurt to give it a try. I have tried on several occasions using amplifiers near the receivers, and it has never helped. If you DO try, don't be confused if you see the signal levels go UP. This doesn't mean that you have any better chance of receiving anything, because in all likelihood what you are seeing in that increased signal level is more noise. If you look at the signal level when you're not aimed at a sat, you'll probably see that go up too. The true test of whether an amplifier is helping, will be your quality reading, not the signal reading. It can't hurt to try, but I'll be surprised if it helps in most cases.

[elgemcdlf]

I can not say if it helps or hinders in my application. I am using with hopes it bumps up signal to help compensate for the long runs of coax. I really wish I would have spent the couple extra bucks and went with RG11 but that is water under the bridge now. I am getting excellent readings from the 90cm which has an amp mounted on the lnbf mounting arm.

Readings like 66-73 for 11720 on G10R that was 33-40 on the 76cm with no amp and a far shorter run of coax. Now the lnbf is different along with dish. The dish pointed at 40.5 is in the 150 - 175' range from the receiver with a DiSEqC about midway. It also has an inline amp mounted on one of the arms of the feedhown mount. Again I am getting excellent readings on many of the tp's. Not so great on others and I honestly have not looked to see if the weaker ones are opposite polarity.

TIP on 87 comes in at 93 but interestingly enough KTEL on 79 was 88 on the 76cm and now about the best I can find on the 90 is 78-79. I have a 80' run for the DSR922 and it hits hard everywhere so I see no need to place any amps on it. Guess I could experiment and take the amps out of the circuit and see what I have. Perhaps one day. Starting to get cold here now so I doubt if it would be this year