Originally Posted by heffneil
I just wanted to ask. I have an appointment with Comcast on Friday. Isn't that fast
. Anyway I wanted to try without the supercombiner. My signal is obviously a problem considering I have two drop amps. Anyway I will have the comcast tech check the signal before and after the supercombiner just to see.
One thing I wanted to confirm is that increasing the signal strength or clarity on the supercombiner couldn't cause a problem?
There is a little drop in the supercombiner but with a decent signal for your home, it definitely should not pose a problem.
A few pointers - to hold the Comcast guy to and how to best amplify...
You should have at least +10dB and preferrably +15dB across the entire cable spectrum coming into your home - watch him carefully as lower channels sometimes droop to much lower power - they are supposed to check that and then go adjust the tilt in their system if it is too far from that. And that is BEFORE any drop amp in your home. The comcast folks really like to get lazy, put in an amp and say everything is ok.
The problem is that amps amplify both signal and noise and while the power may look good on a meter, the noise (which the meter can also measure) is also amplified and your signal quality goes down. Drop amps should ONLY be used to compensate for a lot of splitting.
As for how/where to amplify I'm very much an advocate of doing all amplification at one place - preferrably in one amplifier if needed, and using a good quality amp (truspec or pico macom +15DB with reverse channel no more reverse loss than -1dB - most are about $35 - if you pay less or buy at the local megamart you will regret it)...
I did a thread on amplification - specifically in response to getting rid of hum bars but I think it is a good read for anyone. It is HERE
As for the Supercombiner, they seem to be pretty bulletproof, but they are, after all, electronic components and are subject to ESD at least. If you even suspect you have aproblem with excess noise, too much drop or anything else, let me know and I'll gladly ship you another one to try.
Oh - one more thing. I typically recommend this hookup.
in from cable TV comany
tap off for cable modem (usually a 12dB tap
In to RF-IN of Supercombiner
Wire to Xtender's ANT-IN port to the Xtender port on Supercombiner
RF-Out of Supercombiner to Amplifier input
Amp out to splitter(s)
That way the Xtender channels and the CATV signals get amplified together. The reason is that the Supercombiner has a -50dB filter to get rid of the FM band. But consider what happens if you put the amplifier before the supercombiner and you start with a strong signal (+20dB) - it gets amplified to +35dB then we filter it down 50 dB to -15dB. Well, -15dB is within the discrimination window of many TVs and will cause interference with the BOCS channels. This game is kind of a Zen - it is about balance. Get all the signals about the same up front, amplify them all together in one place, split and distribute - all to get the best possible signal.
Long answer I know - but hope that helps a little.
And I'm MORE than happy to be available for when you Comcast guy is there - keep my cell number handy - I can go another level deeper with him to make sure he gets you what you need.
I've been thinking of having a cable meter for "loan" - that I can ship out to folks who want to borrow one - this would be a good place to use one. I might take that up again.