I am using a channel master antenna. I am looking to split the signal to 4 different rooms all runs less than a 100 foot. Is there any requirements as far as splitting the signal goes? Or is it basically like cable where you measure the signal and amplify or attenuate as needed?

I suggest you try a passive 4-way splitter first. If the rooms are more or less paired, use a two-way at the first split, and then a two-way on each split leg when the runs get between the rooms. The overall losses will be the same, and you'll use less cable.

If you find you have weak-signal symptoms, such as snow or noise lines, you should use an amp. My suggestion would be an in-line booster (the type with the power injector that sends the DC through the coax) installed at the antenna, for best signal-to-noise ratio.

Larry
www.fineelectricco.com

I have done RF work for many years. And have seen bad signal due to to little signal, and also too much signal. I agree with Larry on the try it and see what happens, but, I would use a 4-way right of the bat. That way, you lose it all up front, and if you need, you can add an amp just before the splitter to make up for the loss.

If you have very low RF level at the antenna, then you want to use a Preamp as Larry suggested, this will allow you to amplify the small signal at the source, instead of after the cable run to distribution, thus solving the 'amping the noise' issue that is pretty common in RF.

Just remember, RF is FM (F#$#'in Magic) and can get pretty tricky. I would try multiple spots before you anchor the antenna down, you can have drastic level differences even in a couple of feet.

Matt, I did mention the 4-way first, and I intended the 2-ways as an alternative. I hope RBH realized I meant either the 4-way OR the cascaded 2-ways, not both.

I only suggested the "two-by-two" approach because, when I was a cable subscriber, I wired my own house that way. I have two TV's near each end of the house, and it was more economical that way.

Why have two cable runs side-by-side for a distance, when one works just as well. Also, two levels of two-ways, which provide 3.5db loss each, is the same as a single 4-way, at 7db loss per output.

I realize that this does not comply to the all-home-runs philosophy, but it's not like a phone system that may one day require different phone numbers for different rooms. Besides, I'm a non-conformist.

"That's all I have to say about that." - Forest, Forest Gump

Larry
www.fineelectricco.com

Yeah, but makes for a much more 'proffesional' Headend, and makes any necessary amplification easier. Actually, I prefer to do an 8 way and have expansion capabilities.

I subscribe to the HOME RUN EVERYTHING philosphy myself. We have done jobs here that, a certain electritian has run lowvoltage wires, the job takes 4 days instead of 4 hours because of splitters here and there. Its just makes sense to home run because you never know what you may be doing in the future.

I can't really argue with you both. However, the cable runs I did were on the outside of the house, as we were only renting at the time.

All of the satellite runs I've done are internal, and naturally are home-run to the multiswitch.

Larry
www.fineelectricco.com

Matt,
If you installed an 8-way when 4-way is needed, you could expand it, but aren't you losing 4dB of signal you may need?
=Tom

Here are the steps I take for doing an 'off-air' antenna system.

1) Walk the roof or attic with the appropriate antenna for the area and measure the signal level of the weakest channel in your area. At that channels strongest location, check all the other channels you wish to receive with the antenna. If your receiving less than about 6 dB at the weakest channel, use a preamp at the antenna to boost the signal BEFORE the cable run to the distribution area. This will avoid amping the noise in the run along with the good signal for distribution to the TV's.

2) In distribution, make sure you have atleast 0 dB from the antenna/antenna-preamp combo. This will almost guarantee good pictures through your system. At this point, a loss of about 11 dB is expected through an 8-way, if you use a 20 dB distribution amplifier (make sure to use on that can amplifiy ALL the frequencies of channels you need). This 20dB will drive the 8-way and the loss for each individual cable to your televisions, and probably allow for a local split at a television location if need be. Sometimes you may not even need the Distro amp, if like here, we get 20 dB off the antenna directly. This will make any TV runs added to the system very simple to do, add a cable and plug it in. Otherwise, you have to re-distribute and amp, takes a lot of work. Even if you have more than 8 televisions, using a 2-way out of the amp and splitting to 2 8-ways will only result in another 2.5 loss, probably not requiring any other work than adding those two splitters, the 20 dB distribution amp will still drive the system. Now you have 16 outputs. If a guy has 16 TV's in his house, maybe he needs another hobby!

Beware, if you distribute IR on your coax, you will need to use a VBC (voltage blocking connector) at the INPUT to your 8-way. Any sort of amplifier will ground out the IR pulse on the line.

While this is a good start, RF can be fairly difficult, cable ingression, ghosting, unbalanced levels can take some time to remedy. Look here for some excellent tips on distribution design and all thing RF in general.

Hope fully that helps a bit, but if you have more specific questions, feel free to ask. I've done hundreds of SMATV systems and have a bit of knowledge in this area.

Does anyone know of an off air antenna where you can adjust the individual elements to point to their particular transmitter and thereby optimize reception? I haven't seen one, but I think it makes sense.

Thon,
I doubt that this exists because you would need multiple elements pointing in multiple directions as well as filtering, but there are other approaches that will work, using multiple antennas. The filtering is so that a good signal on a channel coming in one antenna pointed in the right direction does not mix with the lousy signal of the same channel coming in on an antenna pointed in another direction. For an example of how elaborate this might need to be, see if you can visit the antenna farm of your local cable company.

The following products are available from Pico/Macom and Qintar, and maybe others, through cable and satellite supply houses, and sometimes at electronics dealers. None of them are made to be weatherproof.

VHF:
If you are so lucky that all the channels between 2 and 6 are in one direction, and 7 to 13 in another, an HLSJ (high-low separator-joiner) will mix the signals on one antenna with the signals from the other antenna with pretty good isolation.

If you have to point multiple directions, an MX-12 can be used. The MX-12 is a multiple filter with level adjustments for each channel, seven inputs and one output. An MX-12 made for the Los Angeles market has inputs for channels 2, 4, 5, 7, 9, 11 and 13, and one output. In the most extreme case, you would have seven antennas; each one might need an amplifier because there is something like 20 dB of drop through the MX-12, but you can combine signals from different antennas and adjust their levels to be equal. I used this several times to get signal levels within 1 dB from station to station when making a retail distribution system to 450 televisions.

UHF
The MX-4 allows you to mix four antenna signals. I believe that there are frequency and level adjustments for each input.

UHF-VHF
In those multiple TV setups, I used a UVSJ (UHF-VHF separator-joiner) to combine the equalized VHF with the UHF signals.

Nice post Ernie, this goes a bit deeper, but very good basic information indeed!!

I must say 1 dB delta is pretty awesome, I don't think I've been within 2 dB with an SMATV system. I find the cable slope the hardest thing to solve to get such tight specs.