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Q: Combine 2 cable coaxial channels into 1 for TiVo input ( No Answer,   3 Comments )
Subject: Combine 2 cable coaxial channels into 1 for TiVo input
Category: Arts and Entertainment > Television
Asked by: joechen2000-ga
List Price: $5.00
Posted: 20 Sep 2002 15:15 PDT
Expires: 23 Sep 2002 15:47 PDT
Question ID: 67399
I have an older form of cable coming into my condo, where I have two
coaxial cables.  Each cable is for 1 set of channels (i.e. I have
about 60 channels, the first 30 channels are on the first coaxial
cable, the second set of 30 channels are on the second coaxial cable).

I need an A/B switch now to watch all 60 channels.  So if my TV is
tuned to channel 3, I can watch one program (i.e. FOX) if I have the
switch on A or if I have the switch on B, I get another program (i.e.

So, the problem is a digital recorder, such as TiVo works with 1
coaxial input.  How do I combine my 2 coaxial channels into 1 to work
with TiVo??
There is no answer at this time.

The following answer was rejected by the asker (they received a refund for the question).
Subject: Re: Combine 2 cable coaxial channels into 1 for TiVo input
Answered By: clouseau-ga on 20 Sep 2002 17:37 PDT
Rated:2 out of 5 stars
Hello joechen,

And thanks for your question.

You need a device to combine two signals with minimal degradation. 

Channel Plus is a well known and established manufacturer of audio and
video accessories. I found one of their very inexpensive combiners
described as follows:

Channel Plus
2 and 4 way Splitter / Combiner
Bi-directional 2 and 4 way splitter / combiners provide a 1 GHz
bandwidth and are ideal for antenna and cable operations. It can be
used to split a signal from a source or combine signals from multiple
sources onto one coax run.

This sells for only $3.50! Note: there is insertion loss (as in all
passive combining devices) so you will lose some signal strength. You
will have to test to see how noticeable this is for you.

You should also be able to find this or very similar products locally
at Radio Shack with the added convenience of local purchase and return
if if it proves to degrade your signal too drastically. Home Depot
also often carries these inexpensive combiners.

A higher quality solution, which seems well priced, is available at
Orbit Communications here: and is
described as follows:

PVS3CA - Three Channel Amplified Signal Combiner

"Some of the more common applications include...simultaneous recording
and viewing of premium channels and off air signals without the need
for an A/B switch..."

Read their entire description for more information. At a discounted
price of $29.95, this seems to be a very good value. Being amplified,
it will maintain the integrity of your existing signal better and will
add less video noise than a passive device.

Alternately,you might wish to consider a satellite dish, which would
have a significantly higher quality signal and range of channels if
you have the ability to mount one aimed properly at your condo. I'll
let you investigate Dish Network for further details on this potential

I hope I have provided you with a selection of solutions to your

My search strategy was coax cable combiner.

Best regards,


Clarification of Answer by clouseau-ga on 21 Sep 2002 11:45 PDT
Hello again joechen2000,

I'm truly sorry my answer did not provide the information you require.
I must admit, even upon re-reading, I am a little confused.

A TV tuner will tune from either an antenna or cable input and select
the channel desired by frequency. A combiner, particulalry an active
combiner, will allow two sets of frequencies to be combined on one
output so that a tuner can select any of the combined signals.

The only reason I can see that this would not work for you is if the
two cables you have entering your condo (which is a situation I have
not encountered previously) both had the same or some of the same
frequencies on BOTH cables. If this is the case, which is not how I
originally interpreted the question, then a combiner will not work.
This would seem to be, in essence, the same as having two cable feeds
by two different cable providers rather than the feed from one
provider split between two physical cables, which is what I assumed
your situation to be.

As I understand "stackers", with a good explanation here , you also would need "unstackers"
and this does this seem to be very specific to satellite feeds as
opposed to cable.

I did find an interesting article here , which says in part:

"Before beginning, I want to take a moment to dispell a couple of
common misconceptions about video distribution. There are two kinds of
things you can do when it comes to video distribution: The very easy
and not-too-expensive; And the pretty hard and very expensive. In
residential video distribution, we have always stayed with the former.
Here are some examples from the "pretty hard and very expensive"

Combining Coaxial Cables With Common Channels I once said: I'll just
combine my in-house UHF channel 22 with the antenna feed. There
doesn't seem to be a channel 22 in my area. My channel 22 will surely
drown out any little bit of any 22 than is coming in from the antenna.
Silly me. It is astounding how little of a signal it takes to screw up
a perfectly good signal...when they are on the same frequency. When
you "combine" two coaxial cables containing RF signals, you have to be
absolutely sure the cables have no frequencies (channels) in

I have emailed Channel Vision, as they seem to play in this area, to
see if they can suggest an elegant solution. I probably will not get a
reply until Monday (if at all) and I will post a further clarification
if I do.

I would like to mention, joechen2000, that Google Researchers are
sincerely interested in providing an appropriate answer for our
customers. Should an answer ever appear to fall short, please ask for
clarification. We will usually try to go the extra mile to obtain more
information or correct a misunderstanding or misinterpretation of the
question. You are also always free to reject an answer (hopefully
after an attempted clarification has failed) and ask for a refund.

I do appreciate that you noted my effort was sincere, and indeed, it

I will post should I find more of value for you, and  I wish you well
in solving this problem.

Best regards,


Request for Answer Clarification by joechen2000-ga on 22 Sep 2002 22:42 PDT
Wow, closueau-ga, you have my fullest appologies.  I should have used
to answer clarification before doing the rating.  Not only are you
going the extra mile, you've done so in a very professional manner.  I
wish you the best.

Clarification of Answer by clouseau-ga on 22 Sep 2002 23:50 PDT
joechen2000, no apology necessary at all. This is a Beta system, after
all,  and we are all learning just how it works and how to make it
work better.

I do want to let you know that I do have email in to Channel Vision
and with luck should have a reply tomorrow or Tuesday. I also have
email in to a programmer acquaintance at TiVo. Should either of these
prove useful, I will post another clarification.



Clarification of Answer by clouseau-ga on 23 Sep 2002 10:26 PDT
Hello again,

Channel Vision replied this morning:

"Unfortunately, there is no real solution to this situation. until of
course, the system is upgraded to a one line system. so.... for Tivo,
for instance, you would need to have 2 converter boxes to make it, there is no simple combiner to put the two lines
together. thank you for your questions."

And, my TiVo acquaintance checked in with a negative reply as well. He
suggested checking historical posts at AVS Forums, I
searched there for a/b cable and received 478 hits -
and you might wish to browse these discussions.

I refined my search there to a/b AND tivo and shortened the hit list
to only 63 posts. Few seemed to address this problem, however, this
posting looks interesting and on target:

"I have an A/B switched cable box, with HBO on cable B and NBC on
cable A. My Tivo won't switch from A to B or keep listings for both.

Can Replay do this? If so, anybody want to buy a used 30 hr Tivo?

Yes, you can put the A cable directly to the RF input on the ReplayTV
(not using the cable box) and the B cable into the cable box whose
output you connect to one of the ReplayTV's line inputs. You leave the
cable box set to the B side all of the time. You setup the ReplayTV
with CATV on the RF input and Cable B on the line input. ReplayTV will
integrate the lineups with the B side channels having 100 added to

When choosing an A channel, the ReplayTV will use its own tuner for
stations. When choosing a B channel, it will use the IR blaster to
switch the cable box and use the line input.

Here is the only tricky part. The cable box has RF output and the
ReplayTV line input is composite or S-Video. So you need to convert. I
have an old VCR whose tape handling has fallen apart but it has RF
input and composite and S-Video out. So I use it for the converter. In
fact, I run S-Video out from this to my ReplayTV and composite from
this to a newer VCR. This gives me a lot of flexibility.

There may be some converter you can get to change RF to composite. I
didn't really look. Worse case you buy some cheap VCR as the converter
if you have the space for it."

And another:

"for what it's worth, i am using cable in an area that uses an A/B
system. of course, the digital cable box is the one that actually
handles the switching... but when i initially set up the replay, it
was smart enough to include the following configurations:

AT&T cable (A)
AT&T cable (B)
AT&T cable (A/B) digital

(there may have been an A/B analog, i don't remember looking...)

i have the A cable plugged into the RF tuner because that gives me the
chance to sidestep conflicts on the digital cable box's tuner. (i.e.,
i want to watch oz, my girlfriend wants to watch the simpsons, we both
have our way as long as one of the channels is on the other input...
then, while the replay records off coax, i can flip inputs and watch a
direct feed from the cable box).

i am pretty sure there are cable boxes out there that john q. public
can buy that will do intelligent A/B switching as well. 'course, try
and tell your replay how the channels sort out if you do that... ah,
if only we *could* add/reorder channels *AND* do manual record..."

I hope this has been helpful!

Best regards,

Reason this answer was rejected by joechen2000-ga:
Answer was wrong.  Product suggested does not solve problem.  See
Comment given afterwards by ulu-ga... this person gave me an
acceptable answer.  Please take the $5 and give it to ulu-ga.
joechen2000-ga rated this answer:2 out of 5 stars
As mentioned by ulu-ga's comment... the combiner suggested will not
work.  It does seem like you were sincere in your answer, hence 2

Subject: Re: Combine 2 cable coaxial channels into 1 for TiVo input
From: ulu-ga on 20 Sep 2002 23:21 PDT
I don't think using a combiner is a solution to your problem.  I
believe the combiners allow for independent signals (different
frequencies) to be combined.  The PVS3CA (Three channel) probably
combines a channel 3/4 coming from a VCR and puts in on top of the
existing cable channel 3/4.  There is mention of a stacker, which
interleave the channels from two cables together.  I saw that only in
reference to satellite so it might not work for cable.

Read the following and its links for some ideas.

You have a few other options.

Get a ReplayTV (maybe the older models had two RF inputs)

Get digital cable (and the box is then controlled by TiVo(?)), feeding
the audio/video cables to the box.

Maybe have one cable hooked up to a VCR and the other to the RF input
of the tivo.  Have the a/v cables from the VCR go to the tivo.  (Can
you then control the VCR by the tivo?).

Get a Stacker (to combine two cables).
Subject: Re: Combine 2 cable coaxial channels into 1 for TiVo input
From: joechen2000-ga on 21 Sep 2002 00:31 PDT
Thank you ulu-ga.  This was most helpful.  I wish Google can allow me
to accept which person gets the $5, but unfortunately I cannot.  :(
Subject: Re: Combine 2 cable coaxial channels into 1 for TiVo input
From: ulu-ga on 21 Sep 2002 16:53 PDT
I am slightly familiar with the problem since our area also has the
A/B cables, but not owning a TiVo has me at a slight disadvantage.

Google Researchers can provide more detail or corrections using the
clarification process.  You might want let the researcher add more,
when there are comments or addition questions.  As you can see by
clouseau's clarification, they do go the "extra mile" to help
(certainly more than some cable companies).

Judging from the comments posted elsewhere about the A/B problem, this
problem hasn't found a great solution, but several workarounds.  Maybe
clouseau can answer if TiVo can control the channel a VCR is on.  That
might be an adequate solution (feeding A into the VCR and B into

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