Advice on my splitter/amplifier/combiner setup

[CubsWin]

I have a setup consisting of multiple splitters/combiners and amplifiers. A Comcast technician came out today for a cable card installation and he advised me that my signal was overamplified (about +17 coming into TV1) and that it could cause problems. My setup looks something like this.

                                           |
                                      Line in
                                           |
                                           v
                          PCT 4-way powered amp
                     /         |          |      \
                    v          v          |       v
         Cable modem          TV1         |     Capped
                            (+17db)       |
                                          |
                                          v
                                      Notch filter
                                          |
                                          v
             Mod. channel 70---->3-way combiner<----Mod. channel 73
                                          |
                                          v
                               PCT 4-way powered amp
                               /       |     |     \
                              v        v     v      v
                             TV2      TV3  Capped   Capped

Can anyone help me and advise what I should do with this setup to eliminate any potential issues? Is it as simple as a couple strategically placed attenuators, or do I need to do some more significant re-design? Thanks.

 

[iliketj]

what's the level at the ground block? never amp a modem, you'll amp the return it'll cause all sorts of problems, if you have to amp put a two way splitter one for the modem the other leg you can amp that. 17db is way too high, you want around 0 to 3 and ch 2 frequency

 

[CubsWin]

I don't know what the level is coming into the house. I only know that it was +17dB behind the TV because the cable tech tested it. I took your advice and inserted a new 2-way splitter to go to the cable modem and feed the first amplifier. That should help a little bit, but TV1 is most likely still pretty high. Should I insert an attenuator in-line to TV1?

 

[ebms1]

I have a setup consisting of multiple splitters/combiners and amplifiers. A Comcast technician came out today for a cable card installation and he advised me that my signal was overamplified (about +17 coming into TV1) and that it could cause problems. My setup looks something like this.

                                           |
                                      Line in
                                           |
                                           v
                          PCT 4-way powered amp
                     /         |          |      \
                    v          v          |       v
         Cable modem          TV1         |     Capped
                            (+17db)       |
                                          |
                                          v
                                      Notch filter
                                          |
                                          v
             Mod. channel 70---->3-way combiner<----Mod. channel 73
                                          |
                                          v
                               PCT 4-way powered amp
                               /       |     |     \
                              v        v     v      v
                             TV2      TV3  Capped   Capped

Can anyone help me and advise what I should do with this setup to eliminate any potential issues? Is it as simple as a couple strategically placed attenuators, or do I need to do some more significant re-design? Thanks.

well lets do this another way... you have 17 db at your first tv... & probably on all outs of that amp ... so what is the rating of the amp & how long are your runs... i assume you are amping a cable signal ... so you need an amp capable of doing over 77 channels or so...all you need at each tv is 0 db for a perfect picture...usually a rule of thumb 5 or so db is good ... all of your channels are not going to be the same ...only amp your tv signals ...

 

[CubsWin]

well lets do this another way... you have 17 db at your first tv... & probably on all outs of that amp ... so what is the rating of the amp & how long are your runs... i assume you are amping a cable signal ... so you need an amp capable of doing over 77 channels or so...all you need at each tv is 0 db for a perfect picture...usually a rule of thumb 5 or so db is good ... all of your channels are not going to be the same ...only amp your tv signals ...

The amps are both 4-port PCT amps with around -7db insertion loss and +7 db per port, which means I probably have about 17db coming in from the outside. I am amping a cable signal (analog and digital), plus a couple modulated channels on the 2nd amp. My longest run is from the 2nd amp to TV2, but that is still only about 25ft and most of my runs are significantly shorter. I have now inserted a passive 2 way splitter at the beginning to feed my cable modem and the first amplifier, so that should be bringing me down somewhere under 17db, but it may still be running a little high. What would be the negative effects of an over-amplified signal?

 

[iliketj]

cable works with rx (return) and transmit (tx) your tx levels on the modem on 109 should be between -9 and positive 9. for tv, your tx levels should be as mentioned 0-5, if you're analog -3 to 5 should be good, i don't think with your levels you even need an amp

rx levels should be between 32 and 52, if you throw in an amp you're amping both the rx and the tx levels which is a no no, my question is why didn't the tech take out the amp??

i haven't really taken a look at your configuartion but you can use dc 6 or dc 9 splitters if you have to instead of amping and splitting but capping some ports

 

[CubsWin]

if you throw in an amp you're amping both the rx and the tx levels which is a no no, my question is why didn't the tech take out the amp??

My amp has a passive return, so it isn't amping the return levels.