channelmaster 3020 VS DB8?

Discussion in 'DirecTV TiVo Powered PVRs & Receivers' started by newsposter, Jan 5, 2006.

  1. Jan 5, 2006 #1 of 13
    newsposter

    newsposter Poster of News

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    channelmaster 3020 VS DB8?
    http://www.warrenelectronics.com/antennas/3020.htm

    40 miles from towers with neighbors house in way....my channels and signals are:

    26 90s (always solid)
    32 mid 70s ( always solid )
    42 20s (If i only aim for this channel, 60 is best signal then others are bad)
    54 50s-60 (very unreliable)
    64 low 80s (dips to mid 70s)
    67 low 80s (dips to mid 70s)

    64 and 67 only came in strong with my DB8 literally touching the inside of my roof ridge in the attic. It's Impossible to go 1 millimeter higher. 6 inches made the difference between unreliable readings (70ish with dropouts to 50s) and I just made that adjustment yesterday.

    The 13 ft long CM3020 (locally 100 bucks so returnable) would take up the whole length of my attic but it's in a part i dont care about. Also note it would be about 3-4 feet lower than my DB8 is now to accomodate the 13 ft length because my roof is 'facing the wrong way' if you know what i mean. I'm also hoping the rear vertical portion of the antenna wouldn't make me have to lower it too much more.

    so my question is: given the signal problems I've noted above, will the 3020 help me if i keep it inside? Or should I just pay for someone to mount the DB8 on the roof? It seems real fun to put together if it's just in a 5ft box now. Will it help get channel 42 in so it's watchable and will it make the other signals even better?

    thank you for your input


    edit not sure it matters but 64 is going back to 6vhf in 2009 but i'm not sure i should worry about that now
     
  2. Jan 6, 2006 #2 of 13
    A J Ricaud

    A J Ricaud Active Member

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    It needs to go on the roof.
     
  3. Jan 6, 2006 #3 of 13
    TyroneShoes

    TyroneShoes HD evangelist

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    The DB8 has better performance than any CM antenna out there, with the single exception of the CM 4228, which has a little better gain and directionality above CH 55. The DB8 rolls off at the higher channels, which might explain your experience. The 4228 also is about 2" thick, and about 40" by 25", making installation in an attic (or outside) a snap. I would try that in the attic, and then migrate to a mast if that doesn't cut it. If the DB8 underperforms for your scenario, the 3020 will likely be worse. Get the 4228.
     
  4. Jan 6, 2006 #4 of 13
    A J Ricaud

    A J Ricaud Active Member

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  5. Jan 6, 2006 #5 of 13
    HomieG

    HomieG Nowhere Man...

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    If we're looking at the same chart, that is Channel 50, not 50MHz. TV Channel 50 is way, way above 50MHz.

    And comparing the 4228 (A) to the DB-8 (S), it's really above Channel 52 or so where this chart shows a meaningful difference. The person looking at these antennas should know what channels the digital signals are on. In the few markets I've looked at, I cannot recall many, if any, that were above Channel 50, but that doesn't mean there aren't any (the OP does list some, though).
     
  6. Jan 6, 2006 #6 of 13
    A J Ricaud

    A J Ricaud Active Member

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    Man, where was my head when I posted that?

    As for channels above 50, there are 7 in the L.A. market, including ABC, CBS, Fox, local PBS; and, UPN. Your point is well taken re: knowing what digital channels are available in a given area.
     
  7. Jan 7, 2006 #7 of 13
    TyroneShoes

    TyroneShoes HD evangelist

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    I could not have said it better, myself. And, they should distinguish the true channels from the virtual channels, as it is the transmitted frequency that counts.

    The terrific hdtvprimer site mentioned has both polar plots and gain charts for many antennas. In general, directionality and gain are proportional at any particular frequency. IOW, if an antenna has higher gain, it likely also has higher directionality at that frequency. It is also important to look at exactly where the sidelobes are. An antenna with sidelobes that point exactly at where a high reflection might come from, such as the side of a high-rise, should be avoided in favor of one that has sidelobes somewhere else. A notch in the polar plot is much better at that direction, for instance.

    Since gain can be dealt with after the fact with amps, FM traps, and attenuators, and since directionality can really only be addressed by the choice of antenna, I recommend fitting the directionality of the antenna to the scenario first...if they all come from the same direction, get a highly-directional antenna no matter how far away you are, which will minimize multipath interference. Then, deal with gain afterwards. Add an amp if needed, or add attenuation if needed.

    And generally speaking, if you are interested only in channels 7 and up and all come from the same general direction, there is no better antenna choice, considering the plots and charts on hdtvprimer.com, than the 4228.
     
  8. Jan 7, 2006 #8 of 13
    HomieG

    HomieG Nowhere Man...

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    I use the 4228, and pickup Atlanta's Channel 8 (PBS-Analog) and NBC/WXIA Channel 10 (DTV) & 11 (Analog) very well, some 32+ miles away. In fact, Channel 11 reception is the best with the 4228, more-so than the other analog Atlanta stations such as 17, 30, 36, 46 & 69. Not that they are bad, but the reception on Channel's 8 and 11 are superior with the 4228, and they are VHF! I bought the 4228, however, for the DTV signals, and they start here at Channel 10. It's a great antenna, highly directional. For my location that is OK since most of the signals are within 10-degrees this far from their transmitters.
     
  9. Jan 8, 2006 #9 of 13
    newsposter

    newsposter Poster of News

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    So then being that all but one channel is the same direction for me, and the other is 2 degrees off, the DB8 should be just fine...once on the roof :)
     
  10. A J Ricaud

    A J Ricaud Active Member

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    Yup.
     
  11. newsposter

    newsposter Poster of News

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    might as well finish the story:

    They mounted the DB8 on the chimney with a 10ft pole this morning but it appeared even though it was on the roof, I couldn't get in ch 64 and 67 in the high 80s like i did in the attic. My guess is the chimney was 5 ft to the right of the original spot inside and i guess that made the difference. But i didnt' want the hassle of a tripod.

    Anyway, after over 1 hour of struggling aiming the antenna 1 millimeter at a time, and trying a pre amp from the guy (turns out my regular amp was better anyways), I've now gotten fox to be solid mid 60s and channel 67 and 64 seem to be solid 68ish or 72 ish. If everything stays as is, i'll be thrilled as I can record solid 60 signals. Even channel 54 is a solid 65 now. But I was wondering if the dense fog helped or hurt the aiming this morning? If all the channels die tonight after the fog is gone, i'll scream lol.
     
  12. dwynne

    dwynne New Member

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    I guess it depends on what "same general direction" is? The DB8 has a wider beam width (4 degrees on average and as much as 7 degrees) on the primer charts. Would that not be a help if all the stations were a little more spread out? The DB8 has a split screen which means it does not work as well at VHF frequencies, but doesn't that mean you could have even more flexibility in how you set it up to make it even a wider beam width?

    Just curious.

    Dennis
     
  13. A J Ricaud

    A J Ricaud Active Member

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    Re: split screen; I really wonder if that has that much of an effect. A respected poster at another site has said the same thing, though. I have a DB4, which is essentially half of a DB8, and it picked up VHF channel 7 and above quite well.

    Re: flexibility; Judging by the DB8's assembly instructions it looks like you would have to do some fooling around with the mounting if you wanted the 2 vertical assemblies to toe-out and pick up more horizontal beam width. I suppose it could be done by putting some angled wedges between the mount arms and the antenna assemblies. I hope this makes some sense.
     

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