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Thread: attenuator for cable tv.

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  1. #11

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    Quote Originally Posted by KA9JLM View Post
    It sounds like you are within target according to this;

    Downstream Received Power: the DOCSIS specification requires cable modems to function correctly with downstream power levels in the range -15 dBmV to +15 dBmV: power readings at or close to those extremes are likely to be unacceptable. However, when connected to a real-life CATV network, a cable modem might be functional over a narrower range than this. Accordingly, cable ISPs will specify an even narrower target range when commissioning their network: this target range will differ according to ISP.

    http://homepage.ntlworld.com/robin.d...ps/signal.html
    Not sure thats up to date with the newer Docsis 3 specs. Comcast here says 8.0 is border line for docsis 3.

  2. #12
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    Quote Originally Posted by KD8GFC View Post
    Not sure thats up to date with the newer Docsis 3 specs. Comcast here says 8.0 is border line for docsis 3.
    You could be correct.

    If that it what they say, and you are paying for it, then I would think that they should make it meet their own specifications.

    It looks like you had no errors, does it have a lot of errors at times, or what is the problem that you are having ?
    "Theory only works perfect in a vacuum." KA9JLM Don

  3. #13

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    I do get errors from time to time. The thing is Comcast wont do NOTHING till there is a major problem that I can see coming in the near future. I already know how to solve this issue if I could find the above mentioned anntenuator I know they make them just cant find were to purchase it. Thats why I asked here on the Zed if anybody knows were to get them. Thanks for all the replys.

  4. #14
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    Quote Originally Posted by KD8GFC View Post
    I do get errors from time to time. The thing is Comcast wont do NOTHING till there is a major problem that I can see coming in the near future. I already know how to solve this issue if I could find the above mentioned anntenuator I know they make them just cant find were to purchase it. Thats why I asked here on the Zed if anybody knows were to get them. Thanks for all the replys.
    I am sure you can buy them, custom made. There are many companies that can make whatever you want.

    But I would just make one for much cheaper. Or have your ISP provide one.

    There may be a software tweak in the modem where you can adj the level also.

    Good luck on your project.

    73
    "Theory only works perfect in a vacuum." KA9JLM Don

  5. #15
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    Quote Originally Posted by KO6WB View Post
    The lowpass filters to eliminate TVI from amateur transmitters does exactly that. The values may need to be played with and of course you can make it much smaller. Look in some of the older Handbooks that have different impedance.
    Good luck
    73
    Gary
    Yes, they are easy to build for 75 ohm cable , with only low level RF to deal with.

    I think I would build it to strip off all of the cable TV channels also.
    .
    Last edited by KA9JLM; 04-22-2012 at 01:19 AM.
    "Theory only works perfect in a vacuum." KA9JLM Don

  6. #16
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    Default RF Tilt Attenuators

    Quote Originally Posted by KD8GFC View Post
    I know this is not ham radio related but there are some smart people lurking on the Zed. Does anyone know were I can buy a Forward Pass attenuator for cable tv ?? I need one that will weaken the downstream but let the upstream pass untouched. I have found standard attenuators but not the forward pass type any help would be great. Thanks
    Here is a place that has them.


    http://www.tinlee.com/TV_Signal_Dist...LineEqualizers


    LE7-750-RV.png


    The LE7-750 RV Series are the one that you would want.


    73
    "Theory only works perfect in a vacuum." KA9JLM Don

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