OTA antenna - splitter - signal loss?

6616 Views 16 Replies 9 Participants Last post by kenglish, May 13, 2006

virgil001

Discussion Starter · May 9, 2006

How much signal loss is involved with splitting the coaxial cable coming from my OTA antenna to my STB's? Would an amplifier at each STB make up for that loss? Is it better or worse to split the cable closer to the antenna rather than, say, 30 feet away?

I'm trying to decide if I need to run an entirely new RG-6 line from my antenna in the attic to the basement I'm finishing before putting the drywall up. If splitting 30-feet down the line isn't a problem I could save some time splicing into the line where it enters the basement now.

Thanks,

V

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1 - 17 of 17 Posts

kenglish

· #2 · May 9, 2006

Splitting can go wherever it is most convenient. A 2-way splitter drops the signal about 3.5 dB.....3 dB being half the power in to each port, plus about 1/2 dB of connector loss. Don't fool around with any amplifiers, unless you know exactly what you're doing. They can be tricky, and cause major problems.

If any amplifier was needed, it would be a preamp at the antenna, or a distribution amp before the splitter. You probably don't need either, unless the run from the antenna to an individual outlet is more than 100-150 feet.

Rick_R

· #3 · May 10, 2006

When you buy splitters be careful. As kenglish said a good one should drop the signal by 3.5 db. When I bought my splitter Radio Shack had splitters for $4 and also the splitter I got that claimed a 3.5 db drop but it was $8. Some splitters are less efficient than others. If you live in a difficult OTA area ,as I do, the difference is important.

Rick R

NightHawk

· #4 · May 10, 2006

It's important to buy one that also provides and specifies its isolation between output ports. Cheap resistive dividers have none and a good hybrid divider will have a minimum of 20 dB of isolation. This prevents reflected signals from one port interfering with the receiver on the other port.

Rick0725

· #5 · May 10, 2006

Quote:

Originally Posted by virgil001
How much signal loss is involved with splitting the coaxial cable coming from my OTA antenna to my STB's? Would an amplifier at each STB make up for that loss? Is it better or worse to split the cable closer to the antenna rather than, say, 30 feet away?

I'm trying to decide if I need to run an entirely new RG-6 line from my antenna in the attic to the basement I'm finishing before putting the drywall up. If splitting 30-feet down the line isn't a problem I could save some time splicing into the line where it enters the basement now.

Thanks,

V

please describe your setup...times split, antenna, etc.

dkantor

· #6 · May 10, 2006

Quote:

Originally Posted by Rick_R
When you buy splitters be careful. As kenglish said a good one should drop the signal by 3.5 db. When I bought my splitter Radio Shack had splitters for $4 and also the splitter I got that claimed a 3.5 db drop but it was $8. Some splitters are less efficient than others. If you live in a difficult OTA area ,as I do, the difference is important.

Rick R

I had a cheap splitter and was unhappy with the PQ due to the signal loss. I replaced that splitter with a $15 Monster Cable splitter ( http://www.circuitcity.com/ssm/Monst...oductDetail.do )

and the difference was significant. The $8 RS splitter is probably as good as the Monster Cable splitter, you might want to buy both and compare them, then return the weaker performer.

greywolf

· #7 · May 10, 2006

I'm up to my neck in $3 splitters for the 4 VCRs and 4 TVs and associated D* HD receivers with OTA inputs plus FM antenna connections. I've never done anything about the VCRs because the wife and kids still use them. They work fine.

AntAltMike

· #8 · May 11, 2006

Aaaarrgh!!

Rick0725

· #9 · May 11, 2006

The 79 cent 2 way splitters that I purchase at the distributor work just as fine as the 14.95 splitters....or $5.95 ones for that matter. Look at the 1.95 to 3.95 price range and the gold versions are ...just gold.

my 79 cent splitters are not garbage...just an illustration of the markup on there devices.

Look for a rating of

900mhz

**1000 mhz good

**1500mhz better

2000 ghz used for satellite applications

the loss ranges from 3.5-3.7 db

In regards to signal quality of the signal after the split...alot depends on the db of signal going in...if the level in of db is higher ...signal loss will be less noticeable cause the signal level is over the threshold of the receiver coming out.. If the signal level in db is lower going in, the level coming out may be less then the threshold of the receiver and more noticeable.

You can debate this...but there are are a ton of variables involved and splitters are just a part of them.

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Rick_R

· #10 · May 11, 2006

If you have a good signal strength the 79 cent splitter will do fine. I live in a difficult OTA area and I used a cheap splitter and lost two stations. I saw the Radio Shack splitter that claimed 3.5 db and tried it and lost no stations. (I use the splitter to split between my Dish 622 receiver and my MIT MDR-200 OTA only receiver connected by firewire to a Mitsubishi 1100 DVHS for recording.)

Rick R

AntAltMike

· #11 · May 11, 2006

If you have lousy signal strength, the 79 cent splitter will do just as fine as any other price splitter. There is nothing in the design of more expensive splitters that would tend to reduce their insertion loss. In fact, If you take the published numbers seriously, you may notice that Blonder Tongue, Scientific Atlanta and Sonora splitters, which publish loss figures at different frequencies, claim greater losses at UHF frequencies than the cheap splitters do. But they probably don't have greater loss, they just make an effort to publish their actual losses, whereas the companies making cheap splitters probably copy their loss numbers off each other's product specs.

Rick0725

· #12 · May 11, 2006

Im going to say this again and maybe it will sink in.

In regards to signal quality of the signal after the split...alot depends on the db of signal going in...if the level going in db is higher ...signal loss will appear less noticeable because the signal level is over the threshold of the receiver. And the spec of a splitter does not mean a thing...the signal is going to look great. It will even look great on a 2 cent 2 way splitter...and I challenge you to tell me you can see a difference.

If the signal level in db is lower going into the splitter, the level coming out may be less then the threshold of the receiver and the losses appear more noticeable.

It is all db system mathematics that rf distribution engineers work with every day.

A 2 way splitter attenuates the signal by 3.5-3.7db...in an expensive one, a $4.95 one, a $2.95 one, and a 79 cent one...a gold one and a silver one.

My 79 cent splitters are high quality 2000mhz splitters that retail in the stores between 2-4 dollars.

Splitters are rated 900mhz, 1000mhz, 1500 mhz, 2000mhz, and 3000 mhz. This is bandwith, a measure of how much of a spectum of signal is allowed to pass through without detriment.

its back to the same concept

In regards to signal quality of the signal after the split...alot depends on the db of signal going in...if the level going in db is higher ...signal loss will appear less noticeable because the signal level is over the threshold of the receiver. And the bandwith spec does dot mean a damn thing to your signal quality.

If the signal level in db is lower going into the splitter, the level coming out may be less then the threshold of the receiver and more noticeable.

It is all db system mathematics that rf distribution engineers work with every day.

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Targus

· #13 · May 12, 2006

Quote:

It is all db system mathematics that rf distribution engineers work with every day.

You have a very simplistic understanding of RF levels, and bandwidth. The fact that you repeated yourself 3 times, does not make you any more correct.

A 2 way splitter will have an insertion loss of 3.5dB. The signal output by this splitter wil be 3.5dB lower then the input...extremely basic concept. Your talk about signal loss "appearing" to be less is just talk. This depends on the quality of the tuner being fed.

Since the topic is cable tv, a splitter with a 1Ghz bandwidth is all that's required.

Rick0725

· #14 · May 12, 2006

so what are you trying to tell us ...what I already said.

Quote:

Originally Posted by Targus
You have a very simplistic understanding of RF levels, and bandwidth. The fact that you repeated yourself 3 times, does not make you any more correct.

A 2 way splitter will have an insertion loss of 3.5dB. The signal output by this splitter wil be 3.5dB lower then the input...extremely basic concept. Your talk about signal loss "appearing" to be less is just talk. This depends on the quality of the tuner being fed.

Since the topic is cable tv, a splitter with a 1Ghz bandwidth is all that's required.

Quote:

In regards to signal quality of the signal after the split...alot depends on the db of signal going in...if the level going in db is higher ...signal loss will appear less noticeable because the signal level is over the threshold of the receiver. And the spec of a splitter does not mean a thing...the signal is going to look great. It will even look great on a 2 cent 2 way splitter...and I challenge you to tell me you can see a difference.

If the signal level in db is lower going into the splitter, the level coming out may be less then the threshold of the receiver and the losses appear more noticeable.

It is db system mathematics that rf distribution engineers work with every day.

A 2 way splitter attenuates the signal by 3.5-3.7db...in an expensive one, a $4.95 one, a $2.95 one, and a 79 cent one...a gold one and a silver one.

My 79 cent splitters are high quality 2000mhz splitters that retail in the stores between 2-4 dollars.

Splitters are rated 900mhz, 1000mhz, 1500 mhz, 2000mhz, and 3000 mhz. This is bandwith, a measure of how much of a spectum of signal is allowed to pass through without detriment.

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AntAltMike

· #15 · May 12, 2006

This matter will be referred to the Department of Redundancy Department, forthwith.

Targus

· #16 · May 12, 2006

Quote:

so what are you trying to tell us ...what I already said.

No, just corrected what you felt you needed to repeat...3 times.

kenglish

· #17 · May 13, 2006

Buy one of the splitters and open it up. If it has a toroid or two and several equalizing capacitors inside, it's a good one. If no caps, it probably isn't the best.

And, score more points if the back was soldered on, instead of glued or (yuch!) pressed on.

1 - 17 of 17 Posts

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