Almost perfect in NJ - need final tweaks
 

Looking for suggestions on the following setup - my report is below;

http://www.tvfool.com/?option=com_wr...cc495ccfa8def3

I have two antennas split with a diplexer, one pointing to NY (93 compass) the other pointing to Philly (212 compass) both in the attic. The NY antenna is a AntennaDirect C2, the one pointing to Philly is a larger, older antenna from the previous house owners (looks like one of the Winegards but i cant find a model number anywhere). They are several feet apart, and there is about 15 feet of cable coming from each running into the diplexer, which then feeds right into an RCA preamp before continuing through the house to one test TV. I have the preamp power plug linked into the line about 6 feet from the TV.

I'm getting about 30 channels, mostly NY which is what I want all with 90% or higher signal. I'd like to pick up one or two more but not a big deal. I'm not getting many Philly stations but I'm going to try to keep calibrating the aim. A few questions I was hoping some of you could clarify:

- The preamp power - does this matter where in the line once in the house it is added?
- I noticed the diplexer I bought says its for antenna/cable and satellite combining... does that matter? The philly antenna is running through the SAT input and the NY antenna is running through the CAB/ANT input.
- Once I start splitting off to additional TVs, should I add a amplifier somewhere at the first split?

Thanks for all your help this site is great!!!!

My suggestion would be that you start at the beginning, the antenna(s). Prove reliable reception at the antenna, with no accessories such as splitters, combiners or amplifiers... just the antenna (one antenna at a time), a short coax and a known good TV. Once you have a reliable signal to work with you can build the rest of the system.

Too often people (myself included) assemble a complex system, then try to fix symptoms by adding more complexity (amplifiers seem to be the favorite 'fix' for any and all reception trouble). Rule of thumb: Simple is usually far more reliable than complicated. (AKA: KISS)

There is usually a fair amount of flexibility regarding the length of cable between the preamp and power supply. The typical preamp power supply is best attached to the opposite end of the same coax connected to the output of the preamp. Most installations use no more than 100' of coax for this run, but the run can be longer. In specialized applications, running power through a splitter or combiner may be a requirement. The splitter or combiner would need to be designed to pass power on the correct ports. The documentation for the preamp and splitter or combiner will need to be read and understood.

It matters. This is one of the reasons you see little from Philly. TV/SAT Diplexers are not appropriate for combining two OTA TV antennas, The SAT port is filtered, intended to allow frequencies above the OTA TV bands. Satellite dishes are typically equipped with a low noise block converter (LNB) which converts the signals from the satellite (roughly 12 GHz in the Ku band) to a range between 1 & 2.5 Ghz. This is a frequency range that RG-6 coax can support with far less loss. The SAT port is blocking most if not all of the Philly signals... which may actually help your NY reception by blocking interfering reception from the Philly aimed antenna.

If you are trying to combine two antennas that are receiving signals from the same band, UHF or VHF, your chances of success are not 0%... but they're far less than %100. You can try a common 2-way splitter connected backwards... but most folks that try this find the signals from each antenna interfere with each other, resulting in less reliable reception from one or both antennas.

Another rule of thumb: One amplifier can be too many. Two amplifiers are almost always too many.

Amplifiers are only able to 'push' signal through loss. An amplifier can not 'pull' signal from an antenna or out of the air. Amplifiers add noise and distortion to the signal so using an amplifier can make reception worse if it's it's not needed, the wrong type or installed in the wrong place.

The best place for an amplifier is 'upstream' of the loss(es) that it's intended to overcome. Yet another rule of thumb: More is not always better. Know the amount of loss you need to overcome, use only the amplification needed. Loss is expressed in decibels (dB). Simply add the loss values in dB. RG-6 should have no more than 6 dB loss per 100'. Splitters should be labeled but expect a 2-way splitter to have no more than 4 dB loss, a 4-way... 8dB, 8-way... 12 dB.

Your NY reception sounds surprisingly good for an attic mounted CS2. If we were neighbors, you'd see a Winegard HD7698P on my roof, as high as I could safely get it. Going for Philly, I would opt for the Winegard HD8200U.

Both antennas would be equipped with Antennas Direct CPA-19 preamps and cabled separately into the house. I wouldn't bother trying to combine the two sources into a common coax. My preference is to use HTPC with network attached tuners. There are other valid ideas and viewpoints though.

http://forum.tvfool.com/showthread.php?t=820
http://forum.tvfool.com/showthread.php?t=2882

Thanks for the insight
 

I had a suspicion that the diplexer was the problem. I tried a hybrid splitter/combiner from radio shack and now I'm pulling in 40+ channels so there doesn't seem too be much conflict, and I get just about all the channels I want. I could probably get more separately but this gives me the most convenience.

I agree that based on my distance I'm surprises the C2 is pulling in as much NY as it is from the attic (I didn't event mount it cleanly; it's leaning on a shelf on the east side of the house right against the wall). once I run things through the whole house to 3/4 TVs I'll see if I need a preamp on each antenna but right now putting just one at the combiner seems to be doing the trick.

Thanks much for the help!