Originally Posted by gsr
To update on the above:
1) I swapped out the 6 way splitter with a 2 way splitter and my signal levels went from roughly -3.0 to roughly +3.0 (the exact values vary from channel to channel).
2) I installed the Motorola 15db signal amp and the signal strengths went up to roughly +20.0 (some as high as +26.0 or so). That was clearly too strong, so even though I was able to tuner channels, I decided that it probably wasn't a good idea to leave the amp hooked up. If I get a few minutes free, I may try putting the 6 way splitter back in with the Motorola amp inline before it and see what I get for signal strengths, but I suspect they'll still be too high.
Without being at your house with some tools I can't tell for sure what is going on. But as an RF/Microwave engineer I want to point out some simple truths:
1) There is no such thing as a "clean" 15 dB amplifier. Some are better than others, all will contribute to noise figure and possibly impedance match issues. An amplifier is no substitute for quality, low loss cable, correctly installed, with a minimum of power dividers. A single two-way should be sufficient for a Ceton-tuned house, right? 1 for cable modem, 1 for Ceton. TV is ethernet now, right?
2) Your signal levels, if correct, with good impedance match and not the result of Voltage Standing Wave Ratio (VSWR) caused by 4 other unterminated runs of cable with open circuits at the end, are more than sufficient. I get signal levels (as measured by Ceton) in the -10 to -12 dB range and it works fine. I don't use an amplifier.
Having read all your complaints, and comments about intermittent reception and bad cable drops (that you have actually found), I wonder if your coax wiring isn't your own worst enemy. It sounds like you are on the right track with a two way splitter (make sure it is top-quality and has a bandwidth of 1 GHZ, with less than 1.2:1 VSWR from 1 MHz to 1 GHz).
I would further emphasize the importance of quality RG8 coax cable from your house to the cableco amplifier using SOLID TEFLON dielectric, not the crap expanded foam that breaks down over the years. This is probably what you have in your house. Replace it. Make the cable co measure loss through the line from their amp to your house (they probably used solid teflon, as opposed to what is in your house). Also use only the cableco style weatherproof crimp connectors, not the junk you find at home labyrinth.
I suspect you can (and possibly have already gone some ways towards doing so) fix your problems with proper coax and quality, single 2-way splitter.
Edit: What is an "APC S20 coax passthrough"?
Oh, is that one of those surge-suppressor things? Unless they provide bandwidth and impedandce match measurements I would be suspicious. You need good RF performance, and I do not know that they provide it. Try bypassing it and see if it improves things.