Open Forum → CATV Cable and Splitter Question

I'm a cable cutter.

I am installing an attic mounted OTA Antenna. Right now I have excellent reception of about 30 OTA channels in Atlanta, GA with a $13 RCA TV top antenna, so, OTA signal strength at the house is not going to be an issue.

RG6 will run from the antenna in the attic, outside the house to my cable distribution box which is also outside the house. Right now the box is connected to Comcast Cable which is feeding both broadband internet and CATV signals. My plan is to ditch Comcast Cable TV and retain Comcast Broadband Internet service.

The run looks like this: Comcast cable into a grounding block then into an EVO1-SP-2 Digital splitter. Two legs exit the EVO splitter. One leg connects to the Data Port (VoIP/Modem) input of an Extreme Infinity Premise Amplifier (Model IPA1008D-VF w/0.0 db Fwd Gain and -15 db Reverse Gain), the other to the Video input Port.

From there, cabling runs out of 8 distribution ports on the Amp to the household where there are 8 cable face plates in different rooms of the house. The cable runs are all less than 200 feet (longest in the neighborhood of 75'). No other splitters are present in any of the indoor cable that I can find.

My questions are:

(1) Can I connect the RG6 Antenna Cable directly to the Video input port of the Extreme Amp to distribute the OTA signal to the various rooms in place of the Comcast signal?

(2) Can I connect the Comcast Cable directly to the (VoIP/Modem) port of the Amp, preserving my internet connection with Comcast?

I am thinking the EVO splitter may be doing some frequency splitting between the CATV and Data signals and if I eliminate this, the Internet Connection will be impaired and the Modem inside the house won't recognize it as an Internet signal.

(3) If this is so, do I need to retain the EVO splitter in the TV/Internet network somewhere and if so, where?

Whats the purpose of the splitter before the amp? For the ground? Also, isn't the data port a output? A grounded coupler then direct into the Amps input, with the modem on the data output is the standard way of doing it.Which video input? I only see one input on the amp and that's top left, assuming you amp is;
»ecx.images-amazon.com/im ··· 522_.jpgThat is the purpose of the modem port, yes. Looks like it's passive, which means no amp interference and nothing to break if lose power. You should check your signal levels before and after the amp though, You can usally find it on the 192.168.100.1 page of the modem, but it depends on the model if it's a gateway.Sounds like splitter is not needed. A amp is basically a powered splitter though, so thats why the splitter is somewhat redundant, unless for isolating reasons or if you don't have enough ports. IE, if the amp was causing signal problems you could go Comcast > Splitter > 1 to modem and 1 to amp > rest of house. Alot of it will depend on what signal your starting out with at the street.

PS. you may also want to check with Comcast (or their forum) to see if they use any upstream frequency beyond 42Mhz. They probably don't, but since that's the upstream limit of your amp, its worth asking.

Thank you Hard Harry.

You asked: Purpose of the EVO splitter before the amp?

I had the same question. It is serving as a ground for one thing. It also splits the Comcast Coax into two legs.

After looking at the EVO splitter cabling from it again, one leg heads into the house NOT to the amp. That line is most certainly carrying the Broadband Internet signal. The other leg goes to the input port on the amp. That one is most certainly carrying the CATV signal, amplifies it and distributes it to the 8 output ports on the amp.

The EVO splitter outputs (2) do not differentiate a CATV signal/Internet signal ---- they are both marked -3db. Thus I suspect they are carrying the same signal.

You asked: Which video input .....?

Excellent question which made me go back and look at the amp again. The CATV signal coming off the EVO splitter is going directly into the port at the top left hand corner of the amp.

The port right below it (with the blue tag marked VoIP/Modem) is nothing more than a 15v power input. The cable coming into this input port comes from inside the house and is attached to a power supply.

You asked about the modem read out:

Here's the modem read-out. Appears this readout shows downstream and upstream figures but not power before and after the amp..... or maybe that is exactly what these dBmV numbers are???:
Status

RF Parameters

Downstream

DCID/Freq/Power/SNR/Modulation/Octets/Correcteds/Uncorrectables

Downstream 1 5 597.00 MHz 0.39 dBmV 37.09 dB 256QAM 4855455890 1507 2753
Downstream 2 6 603.00 MHz 0.16 dBmV 37.09 dB 256QAM 2612655402 870 1637
Downstream 3 7 609.00 MHz 0.49 dBmV 37.09 dB 256QAM 2566862132 552 1836
Downstream 4 8 615.00 MHz 0.45 dBmV 37.09 dB 256QAM 2591317653 550 1146

Upstream

UCID/Freq/Power/Channel/Type/Symbol/Rate/Modulation

Upstream 1 20 27.90 MHz 45.25 dBmV DOCSIS2.0 (ATDMA) 5120 kSym/s 64QAM
Upstream 3 19 34.80 MHz 45.75 dBmV DOCSIS2.0 (ATDMA) 5120 kSym/s 64QAM
Upstream 4 21 21.00 MHz 43.75 dBmV DOCSIS2.0 (ATDMA) 5120 kSym/s 64QAM

Status

System Uptime: 11 d: 3 h: 15 m
Computers Detected: staticCPE(0), dynamicCPE(1)
CM Status: OPERATIONAL
Time and Date: Sat 2015-02-28 13:20:04

Interface Parameters

Interface Name Provisioned State Speed (Mbps) MAC address
LAN Enabled Up 1000(Full) 00:15:D1:3D:22:3E
CABLE Enabled Up ----- 00:15:D1:3D:22:3FWhich raises another question: Is the frequency range of this amp (the Extreme you pictured) adequate to cover the VHF band which comprises channels 2 through 13 and occupies frequencies between 54 and 216 MHz, and the UHF band, which comprises channels 14 through 83 and occupies frequencies between 470 and 890 MHz?

I'm not altogether clear on the terms Forward (52-1002Mhz) and Reverse (5-42Mhz) Gain. My sense is that the amp I have is a 1Ghz model and will handle all the UHF and VHF OTA signals. Do I have that right?

DO NOT connect an antenna to the amp if Comcast is in any way connected to it. If you do, you and your neighbors using Comcast's services are not going to be happy - the antenna can back-feed signal disrupting Comcast's services.

Just have a straight run of RG6 to your Comcast eMTA, bypassing the amp completely. Then, you can run your antenna through the amp, distributing the signal to your TVs.

Downstream/Upstream

Looks like the VOIP/Modem port can either be a power input or pass through. Can't confirm since the manuals seem to be hidden on their website, even after I registered.Yes. For every 3.5dB loss, your halving the signal.Your signal readings look great, so I agree with passerby that you should keep the two separate. You should replace the splitter with a coax ground block and run it straight to modem. Then run cable from antenna to input on amp.Yes. When I was talking about frequency ranges, I was talking about the upstream, but since you won't be connecting the modem to the amp (as discussed above) it's a moot point.

This discussion has been awesome!

I love electronics but I'm a novice. For 25 years in the USMC, I worked with some of the best Electronic Warfare techs in the business. I've lost track of most of them. I was a pilot and flew the EW aircraft - EA6Bs. But I understand some of the terms .... enough to be dangerous and usually misguided.

I'm retired now so, I'm going to have more time to become as proficient at this as some of you are. I find it fascinating.

Thanks so much for your informed comments on this project. It's been great and appreciated.

Let me make sure I have this correct.

eMTA or Embedded Multimedia Terminal Adapter, is NOT referring to the Extreme Amp that is amplifying the Comcast CATV signal, right?

My Comcast Internet signal looks like it is running straight into the house and right to the face plate in the room where my modem is connected to it.

What this means to me is that I can connect the incoming Comcast Coax to AND should replace the EVO splitter WITH a coax ground block and then run the Comcast Broadband Internet straight to my modem. Then run (RG6) cable from antenna to the input port on amp (the top left port on the Extreme Amp we've been referencing).

Can you give me a link to a proper ground block? Obviously, this is going to ground the Comcast Internet signal. I'd like to ground the antenna as well? Just connect it through a second grounding bloc to the same ground? Connect a single ground block together?

Correct.Correct.

Pretty much any will do, and you can find them at Walmart/Home Depot.

»www.amazon.com/CableWhol ··· 0CLFGH40You can if you want, but I don't think it's that important. As long as the antenna is not outside. See below for more info

»support.channelmaster.co ··· l-cable-

Disappointing news ......

Went to Best Buy and bought the Mohu Sky Sixty Omnidirectional Antenna. This was going to be my attic mounted antenna.

To test location and signal strength, I placed this multidirectional antenna in the attic, routed the RG6 Cable that came with it out of the attic and down the hall to the nearest TV (a 30' run), attached the powered amplifier (15db) to the RG6 cable and screwed the input line from the amp. into the TV.

Auto-scanned and got 36 channels. The problem is that several channels, most annoyingly the local ABC channel, have a signal strength that is below the receiver threshold for un-pixilated picture.

My TV has a signal strength display. Most of the channels display a sig. strength of less than 30-40 on a meter that goes from 0-100. To put this in relative terms, a signal that booms in above about 40 on this scale will display a solid picture. Anything below that and it pixilates or detunes completely.

I'm using the TV Fool web site for broadcast antenna range and bearing. All the broadcasts sites are inside 50 miles and in an arc from 220 degrees to 280 degrees mag. I get no better reception from the Mohu 60 in the attic, its broadest aspect facing 250 degrees mag., than I get from a TV top amplified RCA antenna that is more directional and requires some aiming to optimize signal strength.

I don't think terrain or trees are an issue. Its a pretty straight Line of Sight shot to the South West where the majority of the TV broadcast towers are located.

I checked all the fittings. While they are crimped and not compression types, they all look solid. I know these crimped fittings can be a source of signal strength loss. The lack of compression fittings concerns me.

My options are: (1) Look for something in the run from antenna to TV causing signal loss/amplify the signal further beyond the 15db that is already present in the antenna installation, (2) Go to a larger Omni-directional antenna from Channel Master, (3) go to a directional antenna from Channel Master with an antenna rotator (I've had one of these before and it was good).

There is plenty of room in the attic to accommodate options 2, 3 but given the location of the broadcast stations and their distance from my antenna, I'm having a hard time reconciling the inability to receive a decent signal at the TV.

Any thoughts?

Visit »www.antennaweb.org and see what type of antenna is recommended for your location and the channels you want to receive.

Yeah, have done that. TV Fool does a much better job than antenna web displaying pertinent information regarding azimuth and power from your address. It actually (at least according to the web site) does a topo analysis that will decrease signal power based on what's in the way for LOS stations. It also displays how each broadcaster delivers his signal (Tropo, 1Edge or 2Edge).

Here's what I think is going on with the attic installation problems I encountered last night:

There is some kind of metallic material on the roof underlying the shingles (I can see it on the inside of the rafters). I think this is scattering the signal. I also think the insulation up in the attic may be doing this as well. So, an attic installation is not going to work no matter what antenna I get.

How did I figure this out:

I took the Mohu Sky 60 upstairs (about 40 feet above ground level), stuck it in a window plugged in the TV (15db amp connected) and wham, in comes 30 channels with only one station pixilating and I think that one is overpowering the ATSC tuner/receiver because it is close (not a channel of interest anyway). The farthest broadcast signal available and received is about 30 miles away. The are all packed in an arc from 230 to 280 degrees mag. So that's a benefit and 250 is exactly the direction my upstairs window is facing. As expected, you have to get this thing high enough up and away from interfering materials to do its job. If you do that, the Mohu works as advertised.

Bottom line the Mohu is working fine. Does a good job collecting the signals within the arc without pointing like I have to do with the TV top antenna. I'm just going to have to hide it outside the house somewhere where the community Gestapo won't see it just driving by (we have rules against outside antennas mounted on the house in our community).

Putting an antenna in the attic is a crap shoot. As you have found out foil backed insulation acts as a Faraday cage.The homeowners association may have rules preventing you from installing an antenna but that violates the FCC. You cannot be forbidden from installing a TV antenna. Don't want to unnecessarily ruffle feathers but if push comes to shove you have the FCC on your side.

»www.fcc.gov/guides/over- ··· ces-rule

/tom

Hmmmmm ..... I had always heard about this but never have seen the link.

Thanks.

I know right where I'm going to mount the antenna on the roof.

Incidentally, I've been looking at additional pre-amplification downstream and before the distribution amp. I think the TV tuners in the relatively new (oldest is about 5y) TVs in the home can handle more than the 15dbs that is already in the Mohu Sky 60 antenna set up ...... maybe up to 30db total pre-amplification.

I've seen some tuneable pre-amps that allow you to increase or decrease amplification allowing you to determine if all your amplifying is the inherent noise in the system.

Thoughts on this? My sense is that the cable run I am going to have from the antenna to the distribution amp is going to degrade the signal badly enough so that the distribution amp (15db) isn't going to boost the 4 signals going through it enough, all of them having cable runs to the TVs from 30 to 80 feet from the distribution amp to lock a picture.

The roll of an antenna preamp or distribution amp is to make up losses in the distribution system (coax and splitters) it can't create a signal that is not captured by the antenna.

A good preamp will also have somewhat better noise figure then the typical TV tuner buying you a few more dB, but that only comes into play for folks like me in deep fringe areas.

Too much amplification is as bad, or worse, as too little, and can be a particular problem if one or more of the stations are very strong resulting in overload.

If you have the time start with the antenna hooked up to a single TV, If that works connect a 2-way and ultimately a 4-way splitter. Depending on when you start to loose some channels will tell you how much amplification to use.

/tom

There are a number of preamps with overload protection that require no tuning, I'd suggest one of those.

In the process of that now .......

I like your point about not being able to make up for an antenna that is just not capturing the signal.

In a previous home, I had good success using a Yagi Type directional UHF roof mounted antenna. Didn't care about the VHF signals as that spectrum carried no stations of interest.

I would have liked to put one of these in the attic but the failed experiment with the Mohu Sky 60 there demonstrates very well the "crap shoot" nature of attic installs.

For best reception, you need to mount it on your roof, preferably at least 10 - 15 ft above it. That should improve your reception quite a bit. And don't worry about HOA restrictions since the FCC is on your side.

If that is still not good enough, you may want to switch to directional antennas such as Yagis. Because of their higher gain, they usually get much better reception than omnidirectional antennas. However, depending on where the TV towers are located, you may need more than one directional antennas for optimum performance, and they usually don't come with a built in amplifier, so those need to be purchased separately.

I plugged Lawrenceville GA into TVfool, exact location will be more precise, but looks like you have a lots of strong signals all in the same direction. Once you are able to get outside, assuming you are able to point in even roughly the right direction, should have great reception.

You probably will not need an amp. The NM column of TVfool is a rough estimate of noise margin, even giving up 7dB with a 4-way splitter still should have plenty of signal.

The problem with the antenna in you attic may not be so much the gross attenuation of signal through the foil insulation as the horrible reflections of a "metal" roof. Impossible to tell for sure without a spectrum analyzer and a moot point in any case since you have proved it doesn't work.

»www.tvfool.com/?option=c ··· 5e836f4f

/tom

Yeah, in my post above, you'll note I'm familiar with these.

You're right about the FCC being on my side re roof top antennas.

However, I am certain my wife will have a fit if I put one of those things on the roof. She hated the big one I had on the roof with a rotator in our previous home ....... worked great!

Secondly, although the FCC is on my side, there's that ruffling feathers thing with the HOA. I'm good with the low profile Mohu Sky 60 on the roof. It is hardly noticeable but a big ol' Yagi? No.

I've also found that these omnidirectional antennas, while convenient and actually do a pretty nice job, have to be completely away from the building/roof/windows, etc. if you want to avoid scatter.

Had the Mohu propped up in a window and it pulled most stations except the local CBS which was weird because it is in the same azimuth as the rest and maybe a mile further from my antenna.

While one channel with an estimated -55.4 dBm (2Edge) came in perfectly, the CBS channel with -62.4 dBm (1Edge), same azimuth, would not lock. Opened the window held the Mohu outside and boom, CBS, locked on loud and clear.

This is a great lesson in signal attenuation caused by just about any material you'll find in a house: roofing, insulation and yes, even aluminum framed windows.

So, yeah, I get the idea of putting an antenna of any type well above the roof line.

Success! ...... well almost.

Got up on the roof. Below the peak a few feet there is an enclosure for the faux fireplace. Sticks up about 7 feet. Attached the Mohu Sky 60 at the top of it and with the included mast, its about 10 feet above the roof.

The antenna has a nice clear shot to the South West. Ran the RG6 down to my test TV and boom, everything comes in loud and clear. The Mohu 60 does have a 15db amplifier and it has to be powered for the antenna to work but, as was posted above, I probably don't really need it. Haven't done a real good channel inventory but I think I got 4 or 5 more channels than I did on my best attempt from inside the house. The antenna is now about 15' higher than it was trying to get it to tune indoors.

So, yeah, these obvious and not so obvious lessons:

(1) Antenna height is probably the most important factor in receiving a strong signal from broadcast towers that are supposedly in range (max 40-50 miles realistically for this antenna; I think the advertised 60 is a stretch unless you have perfect alignment and LOS). IOW, the laws of physics when it comes to radio waves are immutable. No matter how hard you try to bypass them, it just won't happen.

(2) You can't amplify what isn't there. You can amplify cable run and/or connector loss. See laws of physics comment above.

(3) Modern building techniques and insulation pretty much nix comprehensive reception from an indoor antenna, attic mount and so forth unless you really do have broadcast stations inside about 25 miles max. Just too much signal scatter through and around any of these materials. This may be nothing new to those experienced in OTA TV antenna installations but it was to me.

I will admit, with a lot of antenna azimuth jiggering, you can do OK with an indoor antenna set up on each TV but who really wants to do that. My experience is that you have to pretty much be in the center of the broadcast antenna's beam width to lock a station. If you are on the edges of it, even though there is a signal there, the station won't lock.

Last step: I'm short about 20' of RG6 cable to reach the distribution box outside on the side of the house. If the weather is good tomorrow, I'll complete the run to the distribution amplifier, pull off good ol' Comcast TV, plug in the Mohu Sky 60 and see if I can get the signal to distribute successfully in the house.

Right now, there are 8 ports on the distribution amp. In reality, I only use 4 of them. The other four dead end at face plates in rooms without TVs. I'm just going to leave things as they are and see what happens. If there is too much signal loss at the TVs to lock all the channels I got with a direct run to my test TV, I'll cap off the unused ports with 75 ohm caps or rig a new 4 port amp.

This has been fun. Thanks for everyone's suggestions.

One final post .......

Pulled the Comcast CATV line off the input port of the distribution amp. and connected the roof mounted OTA Antenna Coax to the same input port and the signal was carried flawlessly though the installed indoor cabling to multiple TVs in my home.

A post up thread said I'd not likely need any pre-amp. I agree with that although the Mohu Sky 60 is a powered antenna. It does not function without the 15db pre-amp attached to the RG6 Coax BEFORE it goes into the distribution amp. So, all toll the system has 15db pre-amplification and 15db in the distribution amp pushing the signal to four TVs and four other cables that dead end in face plates in rooms inside the house.

My newest (about 3y old and a Panasonic Viera, 50") pulled in 86 stations, probably 30 more than my pretty old Sharp 22" that I was using as a test TV. Not sure I understand the difference in ATSC tuners but the Panasonic Viera pulled more channels and something like 15 FM music stations without any apparent bleed over or FM interference with the UHF TV stations. I was pretty amazed. Nothing seems to be over-powered either as can be the case with too much amplification in the system.

I'm also amazed at the functionality of the Mohu Sky 60. You just have to place it correctly. It is going to disappoint if you don't do that (get it on the roof, as high as possible, not inside or in an attic, not on a eve corner but at the high point of the roof to avoid the scatter affect building materials, shingles and insulation have on incoming OTA signals).

Next up is to hook up my Roku and give it a try. When all is said and done, I will have saved roughly $2000/year on CATV costs with a roughly $250 investment in an antenna, cabling and accessories. That does not include the $89 I paid for one Roku, streaming service fees (around $7/mo.) and the cost of one or two more Rokus ill probably install on one or two more TVs.

I have no idea why people are allowing themselves to get ripped off by the likes of Comcast, et. al.