Coax install question

[b-man1]

I've had my current cable modem install from Comcast for a bit over three years and forgot about this...

During the install, the tech installed an amp, saying the signal was "too weak for X1 service". Ok...no big deal. The amp is a small power adapter w/ 15VDC 400mA output into the coax. It looks like the tech ripped open the adapter and soldered in the wires, since the coax connector is missing...

Anyway, it works fine, but it's installed at the far side of the house where the Xfinity DVR was originally. I only have a cable modem now, so if I can, I want to move the amp into my office where the cable modem is. Do you guys think the placement of the amp itself matters, as long as I use the same splitter and such? If the amp goes out (it's on a UPS), the cable modem loses signal, so it's definitely needed for that.

Ultimately, I'm hoping to add in a few MOCA adapters to use the coax going from the office over to the TV room. It's all WiFi in there now (no way to get Cat6 without running external conduit and drilling through cement walls...not that motivated yet).

Edit: hard to find this thing, but here is an example of what it is: https://www.reddit.com/r/Comcast_Xfinit ... placement/

[FlyingPenguin]

---- EDIT - I think I misunderstood your post originally.

Let me make sure I understand:

1) The amp is somewhere else (the attic, or outside in a utility box) and the power supply is inside feeding power over coax?
2) You want to move the power supply from one room to another room, which will send the power through a different cable, back to the amp, than the original, right?

If so, no you can't just move the power supply. On most amps there is one special coax connection that is reserved for the cable connected to the power supply. It should be clearly labelled "Power In". That MUST be connected to the cable that he power supply is attached to.

So if you want to move the power supply to your office, you'll need to connect the coax cable from your office to the "power in" connector on the amp. Just swap it with the one it used to be connected to.

BE AWARE that some amps have TWO power connectors. One is POWER ONLY and intended to be used only if the power supply is in the same room as the amp. It's only for power and will not send the cable signal over it. The other one will be a combo RF out/Power connector, and that's the one you're obviously using, assuming your amp has both. Below is a pic of my amp, and you can see the dedicated power connector in the lower right corner, while the combo Out 1/Power In connector is in the bottom center.

HOWEVER, you may not even need an amp anymore if, as I think you mentioned, you only have the one modem and no cable boxes anymore. There's probably plenty of signal for the modem. You can bypass the amp/splitter with a coax barrel connector in the attic/utility box so it's directly run to the office, and to the modem.

Worth a try. You should be able to log into your modem's web control panel and bring up a "Cable connection" or "Status" page. Acceptable signal levels for ANY cable modem are pretty much the same and covered on this page:
https://pickmymodem.com/signal-levels-d ... ble-modem/

The problem with an amp is, if you don't need it, all it does is add signal noise.

[b-man1]

there is just the power supply, located inside wherd the main TV is and X1 DVR was previously. only have cable modem now, across the house. there is a splitter at the power supply, then it runs outside to the exterior Comcast box. i need to look in there to see if there is a amp...i dont see one inside, just a basic splitter, so maybe its outside.

the external box splits to the office, master bedroom, and TV room.

[FlyingPenguin]

I was in the process of editing my above post when you posted, so please re-read it.

If you have a power supply inside then there must be an amp (and I assume you've tried unplugging it and you lose the signal?). Amp is usually the main splitter as well. You rarely see amps with separate splitters anymore. The amps are pretty sophisticated nowadays and they do load balancing.

The "splitter" at the power supply is a special one designed to combine the DC voltage and the RF signal, and must be connected properly (jacks will clearly be labelled power, TV & cable).

[FlyingPenguin]

And yeah, if you just have the cable modem alone, I'd try connecting it straight to the incoming cable line without splitters or the amp, and I'd be willing to bet you'll have plenty of signal, unless you have a REALLY horrendously weak signal from the pole, or your wires are in bad shape. One less failure point if it works okay without it.

My old house was 500 feet from the pole and the signal was very weak, but it worked fine with just one box and a modem. When we added 2 more boxes Comcast had to install an amp. Every time you go through a splitter you reduce the power at each jack by dividing by the number of jacks. So a 2 way splitter HALVES the signal strength at each jack. A 3-way reduces it to 1/3 power at each jack, and so on. By the time you go to a 4 way split you're down to 1/4 power at each jack. And it gets worse when people daisy chain splitters. I've seen the output of a 4 way splitterer connected to a 3 way (so 25% signal after the first splitter, and then you're down to 8% at the 2nd splitter. Before digital cable you'd still get a grainy picture, but the digital boxes will just start dropping packets and lose the connection.

The problem is the Comcast techs get lazy nowadays and use an amp to improve a weak signal without first trying to FIX the weak signal. Often all it takes is just a little contact cleaner, or replacing all the coax connectors and making sure they're tight. Replacing any corroded splitters. The box outside gets moisture in it and the rubber gaskets on the coax connectors degrade and let water get in, or sometimes you have a really old install that doesn't even have rubber gaskets or booties on the connectors.

Every fitting is a potential small loss of signal that adds up.

[b-man1]

great info, thank you. I checked the current signal levels and with the power inserter connected, it's:

downstream: s/n 37-38dB, power level 4 dBmV
upstream: 34-35 dBmV

i'll try again when i can unplug the power. i did find that what i thought was a splitter is the power inserter...a 3-way power-in/power-out/to-TV adapter. i still need to look in the box outside when i can as well...


edit: yeah, removing power from it kills the modem connection too. i can't get into the outside box due to the custom lock they put on there, but it's warped enough to see inside and there is a similar distribution block to what you showed. i'll try moving the power adapter/inserter to the office, then connect the cable modem to the TV output on the inserter. not sure if it passes the full frequencies or if it's somehow filtered for TV only, but we'll see. hopefully it doesn't fry something.

[FlyingPenguin]

Comcast doesn't usually don't lock the box. If it's the grey plastic box, it's really not a lock. More like a latch It just LOOKS locked. There's a tab on the size you press and then pop it open. If it was me I'd pop it open and put my own latch or screw on it.

You really don't want to connect the power supply to a different tap on the amplifier (and I'm assuming your office and the current location are different taps). There's only one tap designed to have power. I don't THINK you'd fry anything, but I'd be nervous about feeding DC down a line not designed for it.

[b-man1]

i'll look at it closer...looks like a termination lock, but you are probably right. if i can get it open, i'll swap the connections, if possible. i wish i could get rid of the thing...after looking at the power adapter, the tech split it open to get inside and add the power wires, then soldered the two wires to the end of a coax that plugs into the inserter. super ghetto and i should have noticed it when they first did it...sigh.

[FlyingPenguin]

Like I said, you can probably do without the amp. Just get a barrel to bypass it and connect the modem straight to the cable from the pole. Check your signal levels again and make sure they're in the good range.

[b-man1]

So...finally got into the outside box. Not sure of the exact name, but the lock requires a "star key slam tool" or whatever it's called. This type of tool is used:


https://www.amazon.com/gp/product/B00UFIH956

I picked up a few cheap Actiontec MOCA adapters (sold as "wifi extenders" but include legacy MOCA @ 100Mbps) to test them out and they work perfectly, before changing anything with the splitters and/or amp. Now that I can get into the box, I'll add a POE MOCA filter to block the signal from leaking outside my house, then add a cross-connect coax to connect the old and new coax wiring. That'll allow me to use the MOCA adapters and get wired network everywhere upstairs that I couldn't pull cable to.

Here is the cheap Actiontec MOCA I tested with...will probably upgrade to the gigabit bonded 2.0 adapters at some point. Getting well over 100Mbps now and these are only rated for 100Mbps.

https://www.amazon.com/gp/product/B00FKTMWDE

These are a fraction of the cost of the 2.0 1Gbps adapters, so it was worth testing before dropping $60-$80 per adapter.