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Cablevision and Leviton 1x8 Bidirectional 2GHz Amplifier

post #1 of 11
Thread Starter 
Hey guys,

Not sure where to turn (or post) but I ran into a problem today during my new triple play install.

Some background:
I have cablevision in Piscataway, NJ. I have 8 home runs going to a structured media panel, and I bought a Leviton 1x8 2GHz bi-directional amplifier for the runs.

I recently bought a couple of plasma TVs with cable cards, as well as an HD Tivo.
In addition, I installed a Motorola SBV5120 modem (from cablevision) for internet and VoIP.

The cable guy came out today to install the service, and the first thing he said was "man, it's so nice and neat in the box, but that amnplifier isn't going to work. Our systems are very sensitive..."

He then tested the naked incoming drop line, with his handheld testhead unit, which was showing great signal strength both ways. He then plugged that line into my 1x8 amp, and tested a run coming out of that. The incoming signal was great, but he couldnt get an outgoing signal.

Has anyone had any experience / luck / success with the leviton amplifiers in a cablevision area? I'm kind of bummed that right now, my nice and neat box looks like spaghetti.


Ok, I called Leviton today and asked them about any known incompatibilities with the amplified splitter and cablevision's network.

The tech support lady was kind of rude - I explained that the technician tested the bidirectional capabilities thru his handheld unit, and she said that there was no way it wouldn't work. She told me the 47693-GSM is the latest 1x8 offered by leviton and is absolutely compatible with all cable companies. She suggested that I just unplug the cable company installed splitters and try it out anyway.

I'll give it a whirl and report back. It seems odd though that the test unit wouldnt be able to get a good ping response on an outgoing signal.

post #2 of 11
I found a product description but couldn't find a decent spec sheet on the internet. https://www.tselectronic.com/leviton...63021e1fa8cd2b

What is the spec for the return path? It lists cable modems, but they may / may not operate over the entier 5 - 40 MHz return path required for CATV. Leviton shows other amps stating "bidirectional" as their product name, but not this one. Maybe there is really something different with this amp. I wouldn't go back to the cable company yet. Try a different model first.
post #3 of 11
Thread Starter 
Ok, I finally got a chance to test it out.

I replaced the Cablevision installed splitters (which, incidentally, were only 5-1GHz splitters?) with the Leviton 1x8 2GHz bidirectional amplifier.

The cable modem would not work - which was very odd. The amplifier has an adjustable attenuator on it, from -5dB to +15dB. For kicks, I started adjusting the attenuator. Oddly, when I turned down (to the left) the attenuator, the cable modem kicked on!

Could the signal have been TOO strong? I'm not sure of the technical reason why turning down the attenuator would fix the problem.

Everything is up an running smoothly, and as an added benefit, the panel no longer looks like spaghetti.

It looks like the Leviton folks were correct. Now if I could only find the name of my technician from Cablevision to let him know that this needs to be adjusted for his future installs...

post #4 of 11
I think your amplifier was overloaded. Not because the signal was too strong - the tech checks for that. However, he only measures for one channel at a time.

The amplifier sees all of the channels. In other words, add the power of each signal together (all channels). If there are too many, the amplifier is no longer linear (the signal becomes distorted) and it creates unwanted signals which interfere with the channel you want to watch.

I think that in this case, the amplifier's distorted output (intermodulation product distortion) were stepping on the cable modem's channel.

By reducing the total amount of power to the amplifier, it put the signals back to where the amplifier needs them to be. I had the same problem with pixelation problems on my HD channels. Adding a 6 dB attenuator cleaned everything right up.

The cable company doesn't support home owner's equipment. If you have a problem, you will have to remove it from service in order for them to fix "their" equipment. Just like he did the first time- it worked without "your" amp, so he's done.
post #5 of 11
"I replaced the Cablevision installed splitters (which, incidentally, were only 5-1GHz splitters?) with the Leviton 1x8 2GHz bidirectional amplifier."

If using catv, you only want 5-1GHz splitters. The 2GHz stuff is for satellite.
For kicks, can you run a test by first splitting of the incoming line with a 2 way splitter to feed your modem? Then run the second line to your leviton at full strength and see what happens?
post #6 of 11
If the cable guy said the incoming signal was great, then you are more than likely overdriving the signal going to the HSI. I actually had a trouble call yesterday with the exact same setup. Great downstream signal going into a Leviton 1X8 amp, and the modem would not sync up. I installed a two way splitter, with one leg feeding the modem, and the other leg feeding the amp. Fixed the customers problem immediatley.
post #7 of 11
Leviton amps are famous for putting CPD (common path distortion) back into the return path, don't be surprised if your modem quits working. It may be Cablevision's maintenance dept. shuting down the return signal from your house. The tech should have just split your modem off the 8-way (as others have said) and installed their own amp.
post #8 of 11

Great thread. I am glad someone brought it to my attention.

Can I ask what the final verdict was on the setup?

Is it best to split to cable modem off first or to just adjust the amp down to an acceptable level?

Is the 2 GHz just as good as the 1 GHz? The product description seems to indicate that the 2 GHz is better for systems running ON DEMAND services, etc.

post #9 of 11

Is the 2 GHz just as good as the 1 GHz?

There are no cable systems which extend beyond 1 GHz.
post #10 of 11
Originally Posted by Splotto View Post

Is the 2 GHz just as good as the 1 GHz?

post #11 of 11

Any additional suggestions for this issue?

I bought one of the amp's and things were OK for a while but I am still getting some pixilated pictures on some channels.

I have the amp all the way up.

The issue got slightly better when I removed 3 of the 8 connections to the AMP. However, it's not really a solution.

Can I run more then 1 amp? For example, split the line in 3 ways. 1 to my cable modem, the other 2 could go to their own amp which will feed 4 locations each?

Thanks in advance,
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