OTA amplifier

[Mike88]

My Dish was installed with a diplexer connecting it to my attic OTA antenna. And there are a couple more diplexers in the feed on the way to the Dish DVR. It looks confusing but it works.

However once in a while I get an OTA temporary signal loss. There’s not a lot of room for a larger antenna so I thought about using an antenna amplifier. Is there a recommended amp that is compatible with & can be powered from the DVR’s power supply?

If I have to use a separate power supply & injector, how would I keep the two supplies separate from each other? IOW if I inject power into the coax at the OTA antenna, what blocks the voltage from reaching the satellite dish? Does the power injector only supply power out to the antenna connector? Or does the diplexer block the satellite DC on the OTA connection?

I once saw an adjustable amp with a one piece design. IOW the AC cord went directly into the amp case. But I cannot anything like this at the moment. Has anyone ever seen an amp like this?

 

[whatchel1]

If you amplify the signal close to the DVR input you will also be boosting all the noise too. Not a good thing to do. FM noise could be amplified along w/ the TV signal and that could cause other problems. So it is best to get the amp as close as possible to the antenna. You didn't give much info as to what is your SS and when it drops out is it fast drop out and up and down allot. If it is there may be other problems like multipath too.

 

[DishSubLA]

Amplifying the RF may do you no good with no difference in signal strength in the digital OTA era, unless it is noise preventing the RF from getting through, but most often, that is not the problem. Your issue is most likely gain, or lack of it, at the antenna. This is solved by a superior antenna. Your just not getting enough of the signal to start with and if you don't have sufficient amount of the the digital data to start with you get NO PICTURE, and an analog RF amplifier makes no difference in the world as it can't get any more of the digital data than your antenna is providing, anyway. (an oversimplified non-technical explanation, so please don't beat me up for using plain language)

Another possibility with the signal you can't quite get may be that it is suffering from multi-path and and the MT2's (the OTA tuners used by Dish and TiVo) are known to handle multipath rather poorly. This problem could be solved by a superior antenna that can handle the multi-path issue before it is demod on the OTA tuner.

Also, be careful not to put too much amplification on your run as that can cause the OTA demod to NOT lock onto a channel and you get NO PICTURE. This is a very common error many people make in trying to pull in a troublesome signal.

I'm not optimistic that amplifying the analog RF is going to help, but please let us know if it does or if any solution does solve your problem. It would be of great help to us.

 

[garys]

Being the antenna is inside your home, there would be significant signal loss. Moving the antenna outside may solve your problem.

 

[Barry Erick]

Amplifiers were generally no problem to add back in analog days, but for digital, you can very easily kill the signal by amplifying it. The signals are much different today. Digital, after some signal shows, is more dependent on a clean signal than a strong signal. A over amplified signal will distort the digial signal greatly.

 

[Tampa8]

I keep reading warnings that an amplifier may not or won't work. I agree 100% over amplifying it can kill the digital signal, but an amplifier will in many cases certainly help stabilize a signal, I would say exactly what Mike88 needs. I have a good OTA antenna, there is one Ct station, and two Springfield Mass stations that without the amplifier I don't get, with it, rock solid. I even disagree that if you have no signal without, an amplifier won't get the signal. Maybe in analog, but Channel 40 from Springfield (both ABC sub channel Fox) has 0 signal, nothing. Turn on the amp, very decent signal. In Connecticut, channel 8 (ABC) has an in an out signal, with an amp, rock solid.

As for which type of amp... I do agree at the antenna is the best, but from my experience, if the signal is in and out, the one that just goes inside will work fine. It is possible that if you get a very strong station already, you may have to turn the amp up for weak channels, and down for the strong ones. I have been able to find a happy medium.

An amp will do one other thing. If you find you have to aim the antenna to get one channel, then re aim to get another, within reason, an amp will overcome that and get both/all the channels. The direction of the channels do need to be somewhat near each other. I can get Springfield channel 22 WWLP (NBC) without an amp, if the antenna is pointed roughly North, but if I turn it to get the Ct channels, (West) I don't get it. With the amp I can leave it mid way between, get all the Ct channels and WWLP, including the hard to get Channel 8 out of New Haven. I do have to turn the antenna further North to get Channel 40 from springfield.

 

[Mike88]

I would amplify at the antenna. But I was wondering if one should power the OTA amp using the Dish DVR's DC power supply. Or if I use a separate DC supply how do you isolate the two sources from each other?

 

[whatchel1]

I would amplify at the antenna. But I was wondering if one should power the OTA amp using the Dish DVR's DC power supply. Or if I use a separate DC supply how do you isolate the two sources from each other?

I put a plug for my amp in the attic. I did it to increase the strength so once I split it to other devices I still had enough signal level for all.

 

[leszekm1]

Just to clarify a couple of things. When it comes to picture quality it's the signal to noise ratio (S/N) and not the signal level itself that dictates the picture quality whether in analog or digital TV. All tuners have an auto gain amp at their input that equalizes all signal to the level that the actual tuning circuit requires. (similar to an auto gain microphone amp in your PC for example) The antenna amps will never raise S/N, but they will preserve it through long cable runs and splitters. Here’s how they work. Imagine an antenna that gives you a 12db signal on some channel. Your tuner is connected to it via 100ft of RG6. The RG6 loss is 6db/100ft, so the S/N ratio that the tuner sees is 12-6 = 6db. Now imagine you install a 12db amp at the antenna. So at the antenna you will have: signal – 12+12=24db, noise – 0+12=12db. S/N=24-12=12db just like before. At the tuner after the cable loss you get: signal 24-6=18db, noise 12-6=6db, S/N=18-6=12db. So you have preserved your S/N and your tuner has a much better chance to tune successfully to the channel with 12db S/N instead of 6db S/N.

The drawbacks of all antenna amplifiers is that they are designed for weak signals so it’s easy to overload them with near TV and sometimes even FM stations. What happens then is what happens if you try to use your headphones as regular speakers. Your signal is distorted and your S/N goes down significantly as noise shoots up. So if you do live less than 20 to 25 miles from your nearest TV station then your only choice for an antenna amplifier is the Winegard HDP269. It is the only amp currently in production that can tolerate high input levels. (http://www.winegarddirect.com/pdf/spec_HDP269.pdf)

The diplexers will only pass DC power on the satellite side, so you will have to power feed the antenna amp pre your first diplexer. On the other hand you don’t have to worry about the DC voltage reaching your sat equipment.
Good luck.

 

[Tampa8]

Good post. The reason for my post was to counter the statement that if you can't get a channel without the amp you won't with it. That's just not true. If you are going to say that, then it might be if your antenna see's no signal, an amp won't help. But as in my case and many cases, the antenna can see a signal, but it is too low to transmit through any reasonable amount of coax. So you don't see the signal at the receiver. But insert an amp, it takes that minimal signal and, well, amplifies it to where you can see it at the receiver. But certainly if the signal isn't above the noise level to begin with, an amp won't help.

I will add, as a rule of thumb, if you do not see the channel at all, the best chance is an antenna mast mounted amplifier. But if you get a signal in and out, one that is added indoors will probably work. And as the transmitter gets further away, height of your antenna starts to make a big difference.