Amplifier Recommendations

[TempoNick]

I ran 100' to 150' of coaxial cable underground from the cable box on the outside of the house to the barn. Some of the channels won't come in, so I'm guessing I have I need an amplifier. Any suggestions?

I have an old RCA amplifier from about 15 years ago (from Home Depot) sitting in the basement. I've tried using it before, but for the life of me I don't think it does anything.

 

[harshness]

How many splits before the line to the barn?

Is there any chance the cable was deformed or is severely bent (less than 1.5" bend radius) as part of the burial process?

What, if anything else, is in the burial path with the coax?

What kind of cable and fittings did you use?

Cable TV signal levels are usually pretty hot. It is a relatively extraordinary situation that you would need an amp.

If you do employ an amp, it will have to be installed at the cable box end so think about how you might accomplish that.

 

[TempoNick]

How many splits before the line to the barn?

Is there any chance the cable was deformed or is severely bent (less than 1.5" bend radius) as part of the burial process?

What, if anything else, is in the burial path with the coax?

What kind of cable and fittings did you use?

Cable TV signal levels are usually pretty hot. It is a relatively extraordinary situation that you would need an amp.

If you do employ an amp, it will have to be installed at the cable box end so think about how you might accomplish that.

If I remember correctly, there is a four-way splitter to the outside box where the CATV comes in and the wire to the barn is connected directly to the splitter outside. I don't know what the specs of the wire are, but it was given to me by a friend in church who is a cable installer. In other words, it's the kind of wire a cable TV guy would use.

No splices to the wire with one caveat, it was damaged with a shovel about 20 ft from the outside cable box but I wrapped it up and waterproofed it pretty well. This happened several years ago. (I'm sure you will probably tell me to splice in a new wire here, and I do intend to do that. I will probably splice it from the break all the way back to the splitter so that there is only one connection instead of two.)

Assuming that doesn't work, I see the Channel Master 7777 recommended a lot. Would that work here?

P.S.

Nothing interesting underground, it just goes through a grassy lawn. It passes a couple of hedges and that's it.

 

[harshness]

No splices to the wire with one caveat, it was damaged with a shovel about 20 ft from the outside cable box but I wrapped it up and waterproofed it pretty well.

Coax isn't like water pipe. You can't just fix the leaks in the jacket. Coax is more like fiber in that if the shape is changed enough, you get odd reflections that may cause signal cancellation or at the very least, a change in the impedance of the cable. This is why I mentioned the bits about deformation or quick bends.

Assuming that doesn't work, I see the Channel Master 7777 recommended a lot.

The 7777 is intended as a pre-amp and as such, won't work in this situation. You need a "distribution amp" and it has to be placed at the cable box end as I noted above. Four ways should be well within the range of a 100 foot cable TV run without an extra boost. It is when you go to eight or more than you start to wonder.

The most important thing to understand is that if the signal is messed up, putting an amplifier on it isn't going to clean it up; it will just as readily amplify the nasty elements as it does the desired signal.

 

[TempoNick]

Coax isn't like water pipe. You can't just fix the leaks in the jacket. Coax is more like fiber in that if the shape is changed enough, you get odd reflections that may cause signal cancellation or at the very least, a change in the impedance of the cable. This is why I mentioned the bits about deformation or quick bends.The 7777 is intended as a pre-amp and as such, won't work in this situation. You need a "distribution amp" and it has to be placed at the cable box end as I noted above. Four ways should be well within the range of a 100 foot cable TV run without an extra boost. It is when you go to eight or more than you start to wonder.

The most important thing to understand is that if the signal is messed up, putting an amplifier on it isn't going to clean it up; it will just as readily amplify the nasty elements as it does the desired signal.

Now that I think about it, there is a two-way splitter where it comes inside the barn. From there one line goes to a workshop and another goes to an "office." I'm sure this second splitter is another reason for the degraded signal.

Do you still think I need a distribution amp, or should I try to hook up this RCA amp I have in the barn, before the two-way splitter to see what happens?

 

[waylew]

Now that I think about it, there is a two-way splitter where it comes inside the barn. From there one line goes to a workshop and another goes to an "office." I'm sure this second splitter is another reason for the degraded signal.

Do you still think I need a distribution amp, or should I try to hook up this RCA amp I have in the barn, before the two-way splitter to see what happens?

Coming out of the 4 way splitter your signal is reduced 7 decibels,add another -3.5 db for the 2 way split plus the loss in the coax,that's a lot of loss.
Try hooking the cable directly to the barn,using barrels,no splitters,if that gets the channels to the barn then an amp might help.If the missing channels still won't come in then I would suspect the coax/connectors to the barn have problems.
If you install an amp it needs to be at beginning of the run,not the end(barn).The coax run to the barn should also be RG6 or RG11,if it's RG59 that could also be causing problems.

 

[harshness]

Taking the barn splitter out of the equation as waylew suggests is the first thing to try. A splitter failure is quite rare so don't expect any magic here. If that doesn't help, the signal is being trashed before it gets to the barn splitter.

Again, amplifying a trashed signal will only get you a hotter trashed signal. Nothing you do amplification-wise at the barn end of the long run is likely to help. Amplification must happen where the signal is clean (at the cable box end of the run).

It sounds like this has been in place for a while. If the failure is new but the system was working before, this almost guarantees that the problem is with your repair or there's been a new cut (gopher chew?) that you aren't yet aware of.

If I were diagnosing this problem I'd put a known load on one end of the long run (using a coupler/barrel and something known as a "dummy load" -- a 75ohm resistor soldered into a cable end fitting) and see if the resistance measured between the center conductor and jacket at the other end of the run is much higher or much lower than the known load value. If it is much higher, you've got a cut/opening and if it is lower, you've got a short.

I feel compelled to reiterate that amplifying a bad signal is going to leave you with even more bad signal.

 

[Claude Greiner]

You shouldn’t need an amp at 100-150 feet.

I would be more concerned with where you cut the cable with the shovel and the actual connections first.

With a 100-150 foot run your dealing with maybe a 5-9 dB loss total.

What you could do is take a 2 way splitter at the house and hook 1 port to the barn and off the second port run it into a 3 or 4 way splitter.

It’s usually 7.5 on a 4 way where as a 2 way is 2.5

 

[harshness]

It’s usually 7.5 on a 4 way where as a 2 way is 2.5

At CATV frequencies, even the Holland GHS 2-way is closer to 3.7dB loss.

http://www.hollandelectronics.com/catalog/upload_file/Passives-GHS_GSV-GHS-Blk.pdf

The insertion loss on the satellite and MoCA splitters is considerably higher.

 

[primestar31]

Here's what I used in a similar situation, and it worked perfectly. Amazon product ASIN B001EKCGT8

 

[harshness]

Here's what I used in a similar situation, and it worked perfectly. Amazon product ASIN B001EKCGT8

The system seems to be butching Amazon links lately. I'm seeing the link in the quote but not in the message display.

edit: Oddly enough, the link is showing up in the quote of my reply so those who feel compelled to blame my browser setup need not chime in.

edit2: And now the link appears in your post