OTA antenna combiner same as splitter?

Discussion in 'DirecTV TiVo Powered PVRs & Receivers' started by tazzmission, Sep 19, 2005.

  1. tazzmission

    tazzmission Active Member

    697
    45
    Oct 15, 2002
    North...

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    I am going to be setting up two OTA antennas and combining them into one cable run. I need to do this because I can not pickup my OTA WTAE 4.1 with one antenna and still pickup all of the rest of my locals OTA. WTAE is in the total opposite direction from the rest of the locals in my area. I can combine two antennas.. Aim one at WTAE and the other at the rest of the channels and get all the channels. The rest of the channels are all in the same direction.

    My question:
    is a splitter and combiner the same thing? Do I need a 1GHz or 2GHz? I know I will loose about 3db with combining the signals, but I am close enough for this to work.

    I get 90+ signal strenght when I aim at WTAE only. I get 90+ signal strength when I aim at all of the other channels too.
     
  2. DavidS

    DavidS Member

    468
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    Sep 27, 2000
    Dayton Ohio
    Here is a response I received when I asked a similar question in a related form. Don't know how well this addresses your situation, but I thought I'd pass it on.
     
  3. A J Ricaud

    A J Ricaud Active Member

    1,177
    6
    Jun 25, 2002
    Hacienda...
    They are different. A splitter joins the 2 inputs together, which may cause mutual interference. A combiner has circuitry that prevents the inputs from interacting with one another. You only need a splitter that goes to 1 GHz for OTA.

    I would try the splitter first beacuse it is the cheapest and may work for you.

    If it doesn't then try a "jointenna" search in this forum.
     
  4. TyroneShoes

    TyroneShoes HD evangelist

    3,604
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    Sep 6, 2004
    Not exactly. A hybrid splitter evenly power-divides signal among outputs (or evenly combines signals among inputs), and being a passive device, can be inserted into a signal chain in either direction, depending upon the application. So a typical 2-way splitter can be characterized as a "combiner", and quite often is, especially when combining signal from two or more antennas. Depending upon the application, a 2-way splitter will have one input and two outputs down 3 dB from the inputs, or one output and two inputs, if you take the exact same device and simply turn it around. So a "splitter" is indeed a "combiner", since the same exact physical device is used for both jobs.

    There are also frequency-split combiners that allow a UHF and a VHF antenna to be combined without "mutual interference" (and even those can be turned around and used in the other direction, say if you wanted to connect an all-channel antenna to separate VHF and UHF inputs such as found on an old TV set from the 70's). But a hybrid splitter/combiner will not reject such interference.

    The confusion may come from a third device, normally referred to as a "directional coupler". It has one port normally used for input, another port normally used for output, and a third port normally used for a reduced-level output (sometimes used as an input). It looks very much like a hybrid splitter, but there is one critical difference in that the down-leg is isolated from the output, or "through" leg. IOW, signal entering the typical "input" port will emanate from the other two ports, but signal injected into the down-leg, while it will naturally return to the "input" port, will not go to the "output" port, and signal injected into the "output" port, while it will return to the "input" port, will not appear at the down-leg port. It can be used to combine antennas of different signal strengths together to match levels and provide some isolation from "mutual interference", but is more typically used in loop-type MATV construction and for 2-way cable TV.
     
  5. jcoulter

    jcoulter New Member

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    Aug 27, 2005

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    I used an antenna joiner from Warren Electronics. Here is the link.

    I have the same problem you do. 4 channels one way, one channel 160 degrees the other. Just make sure you get the right joiner, i.e. UHF/UHF, VHF/UHF.
     
  6. tazzmission

    tazzmission Active Member

    697
    45
    Oct 15, 2002
    North...
    That is the exact same site I found. going to order one of those tomorrow and 2 DB2's from antennasdirect.

    I have a DB4 from antennasdirect, but don't want another DB4 since it is a rather large antenna. The two smaller ones should work fine and I can probably put them both on the same mast.

    I will update when I have these installed.
     
  7. RBMD

    RBMD New Member

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    May 1, 2005
    I joined my two antenna downfeeds (uhf/vhf-uhf) with a simple $2.95 splitter turned upside down which worked with only a very slight drop in signal strength from 92 to 88-90. I also tried an expensive $20.00) audiophille spliter with a much higher bandwith ( up to 2300mhz or something) rating that would not work at all. Try a simple splitter first and watch your signal meter for effect. My antennas are very directional and therefore I think I avoid interference.
    Rich
     
  8. tazzmission

    tazzmission Active Member

    697
    45
    Oct 15, 2002
    North...
    Anyone know where I can get a join-tenna other than warrenelectronics? I called them and there is a two week wait for them to get them in stock plus the time for them to deliver it to me.
     
  9. A J Ricaud

    A J Ricaud Active Member

    1,177
    6
    Jun 25, 2002
    Hacienda...
    Here's a Channel Master distributor list fo PA.


    Maybe you can find 1 thru 1 of them.

    Distributor Locator

    Results for Pennsylvania


    Available at Participating Ace & True Value Stores
    Contact Your Local
    Store, For More Details
    Phone: ___________


    Available at participating Lowe's
    Contact your
    local store, for more details
    Phone: ___________


    Cumberland Electronics
    1748 Sixth Avenue
    York, PA 17403
    Phone: (800) 632-9025
    Phone Number 2: (717) 848-1511


    Cumberland Electronics
    622 Columbia Ave.
    Lancaster, PA 17603
    Phone: (800) 242-3703
    Phone Number 2: (717) 393-8304


    Cumberland Electronics
    642 South 20th St.
    Harrisburg, PA 17105
    Phone: (800) 223-3221
    Phone Number 2: (717) 232-9715


    DSI Systems Inc.
    810 Plum Industrial Ct.
    Pittsburgh, PA 15239
    Phone: (800) 888-8876
    Phone Number 2: (724) 325-4606


    HBF Electronics
    6900 New State Road
    Philadelphia, PA 19135
    Phone: (215) 338-1100
    Phone Number 2: 0


    Moyer Electronic Supply
    310 North 2nd Street
    Sunbury, PA 17801
    Phone: (570) 286-6707
    Phone Number 2: 0


    Moyer Electronic Supply
    758 North Locust Street
    Hazleton, PA 18201
    Phone: (570) 455-3631
    Phone Number 2: 0


    Moyer Electronic Supply
    330 East Norwegian Street
    Pottsville, PA 17901
    Phone: (570) 622-7866
    Phone Number 2: 0


    Perfect 10 Satellite Distributing Company
    2780 Commerce Drive, Suite 300
    Middletown, PA 17057
    Phone: (717) 939-0523


    State Electronics
    60 West Fayette Street
    Uniontown, PA 15401
    Phone: (412) 437-6110
    Phone Number 2: 0


    The Hite Company
    1800 Warren Road
    Indiana, PA 15701
    Phone: (724) 349-5260
    Phone Number 2: 0


    The Hite Company
    420 Napolean
    Johnstown, PA 15901
    Phone: (814) 535-1589
    Phone Number 2: 0


    The Hite Company
    2402 W. 15th Street
    Erie, PA 16505
    Phone: (814) 455-3923
    Phone Number 2: 0


    The Hite Company
    Beale Ave. & 31st St.
    Altoona, PA 16603
    Phone: (814) 944-6121
    Phone Number 2: 0


    Tri State Electrical
    1809 Olde Homestead Lane
    Lancaster, PA 17601
    Phone: (717) 291-1861
    Phone Number 2: 0
     
  10. RBMD

    RBMD New Member

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    May 1, 2005
    You can't lose more than a couple of bucks trying my above suggestion. No wait or shipping as splitters are found everywhere. You may not need the fancy stuff. If it works, it works.
    Rich
     
  11. A J Ricaud

    A J Ricaud Active Member

    1,177
    6
    Jun 25, 2002
    Hacienda...
    I'm with RBMD. Try a <$5 Radio Shack or other splitter first.
     
  12. tazzmission

    tazzmission Active Member

    697
    45
    Oct 15, 2002
    North...
    I will try that first.
     
  13. tazzmission

    tazzmission Active Member

    697
    45
    Oct 15, 2002
    North...
    Regular Rat Shack splitter/combiner did not work.
     
  14. RBMD

    RBMD New Member

    56
    0
    May 1, 2005
    Sorry to have wasted your time. My $2.95 splitter worked fine, although it may not have been a RS brand, it was an old one I had laying around with the price tag still on it.
    Rich
     
  15. tazzmission

    tazzmission Active Member

    697
    45
    Oct 15, 2002
    North...
    I also heard that both antennas cables need to be the same length. In my situation they are not. But they can be if I set it up that way.
     
  16. TyroneShoes

    TyroneShoes HD evangelist

    3,604
    0
    Sep 6, 2004
    Unlike 300 ohm twinlead, coax cable in this application is transmission-line technology. IOW, it sees a 75 ohm load impedance as if it were an infinitely long coaxial cable, no matter how long it is, just as if it were a waveguide. As long as the cables are terminated in 75 ohms (which every OTA tuner does) received signals, antennas, and tuners both can't care and can't tell how long the cables are. If CATV/MATV technology relied on matching the cables to precise lengths, CATV may well never have been implemented, or at the very least would cost about 3 times as much as it does.
     
  17. TyroneShoes

    TyroneShoes HD evangelist

    3,604
    0
    Sep 6, 2004
    Tazz:

    If channels in one direction are all VHF and channels in the other are all UHF you should probably use a UHF/VHF hi-lo splitter. That way off-axis interference at the same frequencies entering the opposite antenna will not pass into the tuner, improving directionality at frequency.
     
  18. RBMD

    RBMD New Member

    56
    0
    May 1, 2005
    My cable lengths before the splitter are very different lengths. One of my antennas is uhf only and one is uhf/vhf. As I mentioned above I tried one splitter which did not work, then tried another which did. The one that did was rated to 900 mhz the one that didn't was rated to 2300mhz. Don't know why, that's just the results. Perhaps trying another brand would be worth a go. Both my antennas are pointed in different directions with the big combo antenna aiming at towers 54 miles away and the smaller antenna 7ft below the taller one aiming at a tower 23 miles away. Maby the smaller one below can't pick up the distant tower because of the distance and because it's a directional antenna. Proper spacing of the antennas is supposed to be important also. I also placed an preamp on the 54 mile antenna then combined the signals which didn't work, then put the amp on the combined line after the splitter which did work and improved the signal on both lines. A lot of trial and error was done to get my best signals. Placing the preamp on the lower antenna alone also didn't work. Perhaps someone is smart enough to explain my results, but these are my findings. Hope it helps.
    Rich
     
  19. TyroneShoes

    TyroneShoes HD evangelist

    3,604
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    Sep 6, 2004
    All of your hypotheses seem to be right on.

    Some sat-freq splitters have problems at frequencies lower than 950, which could be part of why that one didn't work, or it just could be bad.

    I assume that in one direction you need both U and V, and just U in the other. Otherwise, see my post to Tazz above.

    Spacing is indeed important. Separate masts are best, but usually not practical. If antennas are within a wavelength or so of each other, it tends to detune the directional pattern. This is also why it is good technique to adjust a bit, step away, readjust, step away, etc. (just a warm body being close to the antenna can affect its performance).

    As you indicate, "a lot of trial and error" is the answer...an object lesson for everyone.
     
  20. bdlucas

    bdlucas Right side up again.

    16,954
    0
    Feb 15, 2004
    Exurbia
    The length of the lines from the antennas to the combiner matters if both antennas are picking up signals from the same transmitter because the signal takes a finite time to travel from the antenna to the combiner and so the length of the line affects the relative phase of the signals when they arrive at the combiner. For example if the signals arrive at the two antennas in-phase but the length of the lines from the antennas to the splitters differs by one-half wavelength they will arrive at the combiner 180 degrees out of phase and so cancel. The transmission line characteristics of coax vs twinlead doesn't change this (except perhaps to affect the speed that the signal travels in the line which affects the relative phase delay introduced by different length lines).

    However if the antennas aren't aligned just right (pointed in the same direction and in the same plane) some of the signals are arriving at the antennas out-of-phase with respect to each other anyway, so as has been pointed out you're in the "try it and see" regime anyway, so an uneven line length from the two antennas could actually work to your advantage.

    If the antennas are pointed in different directions and are fairly directional then to some degree they aren't both picking up signals from the same transmitters, in which case all of the above is less important.
     

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