difference between a single port vs all port splitter

[micky]

What is the difference between a single port vs all port splitter

Also labeled as power passive. I've googled but maybe I didn't phrase
the search right.

Here are two urls but there is no other info there so no point in
looking!


Both have:
This 2 way splitter pass both low and high frequencies so it can be used
with a terrestrial antenna, cable TV or satellite.

Passes 5-2600 MHz signals
Works with Cable TV, Terestrial Antenna, and Satellite

All port power passive $2.39
http://www.solidsignal.com/pview.asp?p=P7002AP&d=Eagle-Aspen-2-way-Splitter-for-Off-air-and-Satellite-signals-%28P7002AP%29&q=p7002

versus Single port power passive $3.99
http://www.solidsignal.com/pview.asp?mc=03&p=P7002&d=Eagle-Aspen-2way-Splitter-for-Offair-and-Satellite-signals-%28P7002%29&c=Signal%20Splitters&sku=

I'd think it would cost more money to have all the ports.

Thanks.

[Tom Miller]

"micky" <NONONO...@bigfoot.com> wrote in message
news:coeptapi25av9na1r...@4ax.com...

Single port power passive passes power to only one of the two output ports.
It has an added capacitor on the unpowered port.

[micky]

In sci.electronics.repair, on Tue, 25 Aug 2015 15:14:13 -0400, "Tom

So I only need this if I have an amplifier upstream that needs power?

Are there spliters that pass power to NO ports? I guess there are so
that means power passing splitters have to say that on their label???

[Dave Platt]

In article <hfpptahsltqbbbp64...@4ax.com>,

micky <NONONO...@bigfoot.com> wrote:

>>Single port power passive passes power to only one of the two output ports.
>>
>>It has an added capacitor on the unpowered port.
>>
>So I only need this if I have an amplifier upstream that needs power?
>
>Are there spliters that pass power to NO ports? I guess there are so
>that means power passing splitters have to say that on their label???

If you don't have any devices which need power, and you don't have a
power injector hooked to the coax, then it really doesn't matter
whether the splitter you use passes DC, or not.

The case where you need a splitter which passes power to one port, and
not the other, is where:

- You have a device on one port which needs power (e.g. a satellite
dish and its LNB) and are providing power over the coax, and

- You have a device on the other port which presents a short-circuit
at DC. Many rooftop TV antennas are of this sort, either due to
the antenna itself (folded-dipole driven element) or due to the use
of a 75-/300-ohm balun transformer.

[Jeff Liebermann]

On Tue, 25 Aug 2015 15:08:52 -0400, micky <NONONO...@bigfoot.com>
wrote:

>What is the difference between a single port vs all port splitter

Rather than describe every possible device that can be used between
the receiver(s) and the antenna(s), perhaps it might be better if you
disclosed what problem you are trying to solve. That would narrow
down the possible devices to only a few.


--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[micky]

In sci.electronics.repair, on Tue, 25 Aug 2015 17:06:24 -0700, Jeff

Liebermann <je...@cruzio.com> wrote:

>On Tue, 25 Aug 2015 15:08:52 -0400, micky <NONONO...@bigfoot.com>
>wrote:
>
>>What is the difference between a single port vs all port splitter
>
>Rather than describe every possible device that can be used between
>the receiver(s) and the antenna(s), perhaps it might be better if you
>disclosed what problem you are trying to solve. That would narrow
>down the possible devices to only a few.

Yes, of course. To use one splitter as a combiner, for two antennas,
and the other splitter as a splitter, to feet the signal to a DVDR and
to a digital-to-analog set-top box that feeds a VCR.

Currently, they use separate antennas. The DVDR uses an outdoor style
antenna in the attic** (pointed towards Washington DC) and a antenna amp
The amp makes some of the DC stations come in fine all of the time, and
the rest some**** of the time, but seems to have overloaded some of the
Baltimore stations some of the time^^. The tech support guy at
SolidSignal.com said that weak signal and overload can look alike on the
screen. So I got a coaxial attenuator (before I talked to him but he
suggested it too) and it works to bring back the local stations but at
the same time costs me some of the DC stations. I had hoped there would
be a sweet spot where all of the stations worked all the time.

And the VCR set-top-box is connected at different times either to a
simple 8-foot wire that doesn't leave the bedroom, or an inexpensive
flat 1-foot square no-metal-parts-showing-except-the-coax-connector,
amplified antenna. The Zenith set-top box actually has a better tuner
than does the Philips^^^ DigitalVDR and before I got the much bigger
antenna in the attic the set-top-box got more channels than the DVDR
did***. By giving it part of the large antenna's signal, who knows
what channels I might get? and at the same time it will weaken the
signal a little and maybe stop some of the overload at the DVDR.

I think both amplified antennas have power injected in their respective
co-ax, but I can do that above the splitters, so the splitters shouldn't
have to carry any power, but it's a good thing I asked here, because it
occurs to me for the first time that if the splitter/combiner does carry
power to both ports, some of that power will go downstream from one
power injector to the splitter/combiner, and back up to the other signal
injector where it willl fight with the power there.

If the polarity is the same and the voltage is the same, will this be a
problem? Just because two different injectors both say negative is in
the ring and postiive the center of the plug, does that really mean the
center wire gets the positive in each case, and even if it does, does it
really mean the voltages match? The two signal injectors could output
two DC voltages that are the opposite of each other, I think. ??? So
should I just make sure I have either a non- or one-port- power-passing
splitter?



Footnotes are progresssively more tangential or off-topic.

^^the overloaded stations would not be a problem except when I'm not
home and I record them, then come home and find that the recording is
blank or checkerboarded with no sound.

**Outside antenna is not possible and imo not needed. The SolidSignal
guy kept pushing an outside antenna even when I said I wouldn't do it.
(I bought the antenna and the amplifier from them.)

****Even in the best weather, I can't get every DC station, but I can
get all the major and some of the minor ones.

***But I don't have the right remote for the VCR so I can't change the
recording speed to a practical one. So I don't record with it. When
all this other stuff is settled, I have another VCR someone gave me that
might be useful for recordign (The Zenith set-top box actually has timed
recording ability, including turning on and tuning at a certain time to
a pre-chosen channel. It was $40 above the government coupon price, that
is, it would have cost $80.)

^^^The Philips is not sold new anymore but is pretty much the same as a
Magnavoxx DVDR still sold afaik. It has lots of design flaws (the
biggest that the clock doesn't keep good time and even setting it on
automatic doesn't mean it will ever have the right time. Putting it on
OFFmeans it will lose (or is it gain?) several seconds every day. (A
friend has a Magnavox and it's no better!) I have to start recording a
minute before the hour and finish a minute after, but this doesn't work
if I want to record two shows in a row on different channels.) But
reading the manual again just now, I realize I forgot the 3rd choice,
manual, where I tell it what the PBS channel is if it doesn't pick it
correctly itself. So maybe it will work better once I do that. I
tink I bought this 7 years ago before digital conversion was mandatory
and used it on analog for a couple years.

It also won't display program information when it's recording, and it
doesn't save any program information except channel, time, and recording
length, not program name and certainly not program description. I often
have to start playing it to figure out what it is. But there are only
2 or 3 over-the-air DVDRs sold, and it does the other basic stuff well.
(Plus it has editing and dubbing powers I will never use. )

[micky]

In sci.electronics.repair, on Tue, 25 Aug 2015 16:49:42 -0700,

Ah, of course. I'm surprised I lasted this long without coming across
this before, or noticing it on my own. Now I have to review the last
30 years and decide if not knowing this has caused me any problems.
Off-hand, I don't think so, but I've learned it takes days or longer to
retrieve things out of the corners of my mind.

[Jeff Liebermann]

On Wed, 26 Aug 2015 02:50:55 -0400, micky <NONONO...@bigfoot.com>
wrote:

>To use one splitter as a combiner, for two antennas,

>and the other splitter as a splitter, to feed the signal to a DVDR and

>to a digital-to-analog set-top box that feeds a VCR.

You have a possible problem. When you take two antennas and combine
them with a splitter/combiner, you run the risk of creating a
situation where the two signals cancel. For example, if you have two
antennas, and both pickup the same station, with roughly the same
signal level, and roughly 180 degrees out of phase, the signals will
cancel in the combiner. Worse, you will probably have different group
delays (phase shifts) between the two antennas at different
frequencies and even on different parts of the 6 MHz wide signal. The
result is a "hole" in the frequency respons (gain) of the combined
antennas. What that looks like on a TV is a tolerably strong signal,
but with a truely rotten picture. With digital TV, it can also be the
equivalent of the old "ghosts" problem, where you have two signals
arriving at different times, resulting in 2 pictures. However, with
digital TV, it just results in a poor quality picture.

Combiner schemes work if:
1. The two antennas can't "see" each other and cover different TV
stations.
2. The two antennas are for different frequency bands, such as VHF
and UHF. You'll need a diplexer to do that, not a combiner.
<https://www.google.com/search?q=vhf+uhf+tv+diplexer&tbm=isch>
3. The two antennas are identical and are pointed in the same
direction. That will give you 3dB more gain, but you'll either a
phasing harness, or two amplifiers and resistive combiner to make it
work.

I suggest you get rid of the two antenna scheme and combiner for now
and see if one antenna works better. Also, you can make it work with
an RF switch between antennas, which admitttedly isn't convenient.

I'll address the rest later. Customer bearing checkbook just
arrived...

[micky]

In sci.electronics.repair, on Thu, 27 Aug 2015 13:29:15 -0700, Jeff

Liebermann <je...@cruzio.com> wrote:

>On Wed, 26 Aug 2015 02:50:55 -0400, micky <NONONO...@bigfoot.com>
>wrote:
>
>>To use one splitter as a combiner, for two antennas,
>>and the other splitter as a splitter, to feed the signal to a DVDR and
>>to a digital-to-analog set-top box that feeds a VCR.
>
>You have a possible problem. When you take two antennas and combine
>them with a splitter/combiner, you run the risk of creating a
>situation where the two signals cancel. For example, if you have two
>antennas, and both pickup the same station, with roughly the same
>signal level, and roughly 180 degrees out of phase, the signals will
>cancel in the combiner. Worse, you will probably have different group
>delays (phase shifts) between the two antennas at different
>frequencies and even on different parts of the 6 MHz wide signal. The
>result is a "hole" in the frequency respons (gain) of the combined
>antennas. What that looks like on a TV is a tolerably strong signal,
>but with a truely rotten picture. With digital TV, it can also be the
>equivalent of the old "ghosts" problem, where you have two signals
>arriving at different times, resulting in 2 pictures. However, with
>digital TV, it just results in a poor quality picture.
>
>Combiner schemes work if:
>1. The two antennas can't "see" each other and cover different TV
>stations.

That's the way they are now.

They now each cover one tuner (the DVDR or the set-top-box/vcr), which,
via an A-B switch, feed the same set of televisions.

>2. The two antennas are for different frequency bands, such as VHF
>and UHF. You'll need a diplexer to do that, not a combiner.
><https://www.google.com/search?q=vhf+uhf+tv+diplexer&tbm=isch>
>3. The two antennas are identical and are pointed in the same
>direction. That will give you 3dB more gain, but you'll either a

3db is about 2x as strong? Yes, Wikip says power ratio is about 2,
amplitude ratio is about the square root of 2. I asked Solid Signal
if splitting the signal to go to the VCR and DVDR would cut the strength
in half and he said, No, only 3db. Then he wanted to know where I
live so he could give me distance and heading to the stations, and then
recommend a second antenna. He didn't pronounce attenuator right,
either. Oh, well.

>phasing harness, or two amplifiers and resistive combiner to make it
>work.
>
>I suggest you get rid of the two antenna scheme and combiner for now
>and see if one antenna works better. Also, you can make it work with

I have one antenna for each device now.

I see the problem and since I was smart enough to think of the DC
voltage problem, I should have thought of what you just said.

Interestingly, the guy at Solid Signal was one who recommended two
antennas and he didn't say a word about it either. And he certainly
didn't push identical antennas or facing them the same direction.

Thanks for warning me.

>an RF switch between antennas, which admitttedly isn't convenient.
>
>I'll address the rest later. Customer bearing checkbook just
>arrived...

Yes, more important.

[Ralph Mowery]

"micky" <NONONO...@bigfoot.com> wrote in message

news:e01vta9d7vrf9obab...@4ax.com...

>>
> 3db is about 2x as strong? Yes, Wikip says power ratio is about 2,
> amplitude ratio is about the square root of 2. I asked Solid Signal
> if splitting the signal to go to the VCR and DVDR would cut the strength
> in half and he said, No, only 3db. Then he wanted to know where I
> live so he could give me distance and heading to the stations, and then
> recommend a second antenna. He didn't pronounce attenuator right,
> either. Oh, well.
>

Yes, 3 db is 2x larger or smaller depending on the direction of change. It
is a log scale so 3 db =2x, 6 db =4x and 10 db=10x.

That is rounding off a tenth or two.

Unless the signals are right on the border point, 3 db or even 6 db won't
make much difference. Especially for the digital signals as they are mostly
good or bad and not fuzzy like the older analog TV signals.

[micky]

In sci.electronics.repair, on Thu, 27 Aug 2015 13:29:15 -0700, Jeff

I've been thinking about this. Don't the inputs for a diplexer have to
be in different frequency bands? Since I have two TV antennas,
they'll be the same frequencies.

And if the "satellite" input filters out some frequencies, what
expectation do I have that they will be the frequencies from Baltimore
(nearby)? Instead it might be filtering out the very DC stations I
wanted the big attic antenna to get?

Also, after some frequencies are filtered out and some are left, will
my DVDR, which expects input from an antenna, not a satellite, be able
to interpret what does pass through the "satellite" half of the
diplexer?

>3. The two antennas are identical and are pointed in the same
>direction. That will give you 3dB more gain, but you'll either a
>phasing harness, or two amplifiers and resistive combiner to make it
>work.
>
>I suggest you get rid of the two antenna scheme and combiner for now
>and see if one antenna works better. Also, you can make it work with
>an RF switch between antennas, which admitttedly isn't convenient.

Right. It won't work because I watch mostly that which I record, so
there's no one at home to flip the switch from one antenna to another.