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Chicago, IL

2 edits

[Equipment] Chicago, Coxial splitter -> modem & HDhomerun?

I currently have RCN in Chicago with a TV (using RCN's Tivo) & internet bundle. My tivo is in one room and the modem in another. Each device has a separate coaxial cable running to it. I want to replace the Tivo with an HDHomerun Prime, which means it has to connect directly into my router. This means I need two coax cables in the modem room, one running to the modem and the other running to the HDHomerun which will be right next to the modem/router.

Can I use a splitter to split the coax so I can run it to both devices in the same room? And would I suffer any loss in quality - speed on the internet side and picture quality on the TV side?

I understand that theoretically it should work just fine, I just don't know if RCN can tell that it's being split and wouldn't allow it.

Thanks for the help

Dr. Zoidberg

Elmhurst, NY
·Verizon FiOS
·Earthlink Cable ..

Re: [Equipment] RCN - Coxial splitter -> modem & HDhomerun?

This is just my advice and I'm sure the experts would chime in as well, but, can't you check your modem signal through
if not, go to the RCN Speedtest and check the power ratings.
If you've got a Cisco/Moto/Zoom, you can check your levels.

Secondly, check the first splitter where the RCN line is being split. On the splitter, make sure the lowest signal loss goes to the modem. If your main splitter is a Coax TAP, make sure the output "other" than the TAP goes to the modem.

You can take the TAP output and place whatever splitter you want there and route coax to your TV/STB Equipment.

As for the HD Homerun, you can take the cable going to the modem and split that with a balanced -3.5db two way splitter. One goes to the modem, the other to the HDHomerun.

Things to know about the power levels:
Transmit power: should be less than 48dbm (mine recently went as high as 48 dbm and still maintained sync with RCN). Basically this is the power out by the modem to maintain a clean upstream you want this to be low (upper 30s or low 40s).

Forward Power: between -12 dbm +12dbm range. Each splitter you install will drop this level by around 3.5dbm. So use your connection diagnostics to see how it pans out as you will be adding an additional splitter before the modem.

SNR: should be better than 30. The closer it is to 38 or 40, the better off you will be.

All that being said, signals may not be everything at play. But mostly, if your levels are good, everything should work fine.

Hope this helps,
"Look at me, I'm Dr. Zoidberg, homeowner."


Chicago, IL
Thanks a lot for the reply.

I am very new to this so I have no experience with checking modem signals, transmit power, or forward power, but now that you've given me some suggestions, I think I can test it out.

One thing I think I might need to clarify is that I won't be using the STB anymore. This means that the coax that runs into that room won't be used anymore. I'm only looking to split the existing coax into the modem so it can go into both the modem and the HDHomerun.

Is it likely that I only have one coax running into my apartment and that there is already a splitter somewhere inside that's giving me the two existing coaxs (into the modem and Tivo)?