I have been doing custom installs for a couple of years now and I've done many cable break outs. But there are still some questions that I have about how to get the best possible result:

My first question is about db ratings when working with cable distribution. All splitters have a db rating but is this a measurement of the amount that is being lost or how much is allowed to pass? What db rating would be considered acceptable or should be my goal?

Also splitters have a measurement of MHz or GHz. Is this saying how much information the splitter will allow to pass? What is considered a quality splitter? Does 1 GHz mean the total amount for the whole splitter or each port?

If you have an 8 way splitter and only 3 wires are hooked up to it does it have the same strength per wire if you had all 8 ports connected?

What do you guys prefer channel amps with multiple ports, or single inline amps that then go into a splitter.

What does it mean when a splitter has DC passing?



I know that this is a lot of questions and I'm sure that none of you have the time to sit down and answer all of them. Any Info that you may have on any of these questions would be appreciated.

This is usualy the dB Loss per Tap


Depends.... -1.5-3 on a 2-way is good, -3.5-5 sometimes on larger taps.


Most Cable systems are under 1Ghz, DIrecTV and Dish go out to almost 2Ghz. Thats not saying is posible to split a Satellite signal traditionally, but there are wasy to do it.... WIth a 2Ghz Spliter.....


As long as the open ports are properly Terminated, you'll get no additional signal loss.


I prefer a quality one in one out Amp with Tilt and Gain control. Allows for finer tuning.


This will Pass 2-Way Cable(Interactive... Payperview) and IR signals back through the splitter.


Ideally, You want to Add as much amplification as you lose through splitters and cable lenghth. Of course, ths is assuming the signal coming into the house is within spec to begin with.

its ALWAYS better to use a 3 way if only connecting 3. Less loss. Always use splitters rated to 1000mhz for cable/digital cable. Dont think a 1ghz-2ghz is better - IT AINT its much worse. Use 2 ghz for satellite systems. As for amps a single with signal attenuation is always prefered. Cable companies in my area have incoming signal varying greatly in stregnth. Check it before amping it. I've had it coming in to hot for stable signal. Try to avoid putting cable modem or digital boxes thru an amp - even if it says bi-directional. They really aren't.

The idea is to "pre-compensate" for the losses imposed by the necessary splitting if the incoming signal is not strong enough.


This is the highest frequency which the splitter will pass without noticeable signal loss. By the way, 1000 MHz is equal to 1 GHz.


Unfortunately, yes. However, it's far better to use a splitter that has the number of outputs that will be used, and changed whenever that number changes. Unused (and/or unterminated via a 75-ohm resistor) ports can cause ghosting on the entire system.


They're basically the same thing; a splitting amp is an amp with a built-in splitter. Separate units allow changing splitters when necessary as described above.


That amplifier power and other voltages can pass through the splitter, such as used with in-line amps and in satellite systems.


You're welcome.

Larry
www.fineelectricco.com

I'm not sure that I properly comprehend the use of 2GHZ splitters for satellite use. If you're splitting the broadband output of a sat receiver (CH 3) for instance...what's the point of having something with that high of a range?

Thanks a lot for all the help.

When you guys talk about terminateing any unused ports of a splitter do you mean useing the metal screw on caps?

To terminate an unused port use a "terminating resistor". It is a metal cap with a 75 ohm resistor in it, the lead of the resistor is the center conductor.

Ahem, The channel 3 output of a sat receiver is at about 35mhz, a 2ghz splitter is not necessary.

A 2ghz splitter would be used to split the output of the dish.

Hmmmmm,

Where's Frank White when you REALLY need the RF info?

"A 2ghz splitter would be used to split the output
of the dish."


I had no idea you could do that.

Is it possible to split the output of a HDTV sat dish right before it gets to the receiver, so that you could feed two HD receivers off of one coax line??

Dawn

Not if you're expecting to get different channels. Use a multi-switch and separate coaxes.

Larry
www.fineelectricco.com

My understanding is that the ONLY use for having a 2GHZ splitter would be for splitting the output of a dish to go into 2 or more multiswitches.

Having been around for a few years, I confess that I've never done this, nor have I seen this done. However, I see 2Ghz splitters in various configurations at just about every retailer in town.

My conclusion is that retailers are up-selling them to consumers for the purpose of splitting the RF output of the satellites when a 1Ghz or lower splitter would work just fine and dandy and at half the cost.

Realize that when you use it "for satellite use," that implies that you are passing the signal from the satellite DISH, which goes up to 1.5 gHz, I believe.

There is no point in using that for a channel 3 signal unless it is a help to just stock one particular type of splitter. That can actually be a help if you do this for a living!

Most of this has been answered, but

In a perfect world, if you took a signal and split it in two, each output would be exactly 3 dB lower than the original. A four-way splitter would be 6 dB lower, an eight-way 9 dB lower. The specs on the splitters tell you what they really do so that you can plan and control your signal levels.

All splitter outputs will be lower than the inputs, whether you have anything connected to them or not. I have not seen an output change level when connecting an additional output, either.

If you need amplification, you want the amp as early in the chain as possible. Each amp increases the signal, but also the noise, on the line. You will have a cleaner signal if you amplify at the antenna than if you amplify indoors after the antenna signal has decreased, say, 10 dB on the cable run (the noise will NOT decrease 10 dB in that run). BUT you have to be sure that the signal at the amp is not already so strong that it causes distortion in the amp, which shows up as wavy lines on some channels, or truly groaty sounding audio.

The DC passing thing will allow IR signals to pass, as for instance from a Xantech UltraLink. I can't think of any other use for this on a cable or antenna...wait a minute! sending power to an amplifier on the antenna!

But some splitters that are not DC passing are actually short circuits to ground for DC, so if you are trying to send DC, you have to measure resistance to ground with a meter before you install. I have also seen the occasional TV antenna input that is a DC short circuit, where a Xantech Ultralink worked fine until that TV was connected. Had to get a DC blocker for that one!

Amplifiers with single ports or multiple ports are chosen simply depending on whether I have a splitter with me, or whether I want the amp away from where I want the splitter. When you say inline, do you mean those little cylindrical amps? I haven't found a reason to prefer those over the type with a chassis except for the fact that you can put them where you want them, but then that is with the drawback that you have to install the power injector somewhere. The chassis type amps are available in more types. Bravo to whoever invented supplying power to a cable amp on a run of RG6, because you can put the amp where you want it and use what you already have on your truck to make a legal extension cord!




No. The receiver sends 13 or 18 volts, with or without 22kHz tone, up the cable to the dish to have the dish send the proper LNB signal down to the receiver. You can't use one of these splitters as you suggest.

I used a couple of them once when I had a dual output LNB-A ONLY system with the dish on the garage and the multiswitch 100 feet away in the house. To get a receiver in the garage, I split BOTH signals coming out of the two halves of the LNB, fed one half of each to a 2-in, 2-out multiswitch (which has no reason to exist other than this particular application), and fed the other half of each splitter to the cables going to the house.

This splitter HAS to be DC passing on both ports so that any receiver, on any channel, will send voltage up to the LNB to power it. It is also mind-boggling how complicated it is the first time you have to figure out your mistake if you take the house 13 and 18 volt lines and connect them backwards, that is, so that the garage receiver sends 18 on the 13 line and 13 on the 18 line.

This message was edited by Ernie Bornn-Gilman on 04/30/04 08:03.