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Sirio Gain Master - First report

Discussion in 'CB Antennas' started by cbradiomagazine.com, Apr 18, 2011.

  1. cbradiomagazine.com

    cbradiomagazine.com 2008 - 2014 / Pau Hana

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    Yesterday I assembled and prepared my Gain Master and Imax 2000 for testing. I decided to skip the A99 as part of the test because I knew it wouldn't compete with the other two and I didn't think we'd gain anything new from including it in the test. Also swapping out two antennas on the same mast was enough fun.

    Here was the setup - 24' mast to the bottom of both antennas (used the same mast, same coax, same location, etc).

    75 foot run of buryflex to Uniden Grant.

    I talked to a local station 15 miles away.

    Imax put a solid 6 on his meter, Gain Master a solid 6.5.

    Receive - I noticed no difference in my readings.

    Noise floor with the Gain Master is slightly quieter than the Imax 2000.


    Now here's where it got interesting - with the Gain Master installed the station saw the very slight boost in signal strength but he said I was noticeably louder and CLEARER compared to the Imax.

    He said my signal came in with less static and his description of the audio said it sounded like I turned something up.


    Now on to the second station - 35 miles distance as the crow flies.

    This station did not have a mechanical meter so this test would be only based on "percieved audio" (somewhat less than scientific :) ). His digital meter (2950DX) showed identical readings for both antennas.

    He gave a report that both antennas sounded roughly identical and could not determine any difference.


    Those were the only two local stations to test with today but on Thursday night we usually have more stations come out of the woodwork so I can get some additional signal reports.

    I also found out this weekend that with the Imax 2000 an elderly neighbor can hear me through her 20 year old TV. I have a low pass installed and I put a high pass on her TV but she can still hear me (first complaint I've ever had in my life from a neighbor).

    Tonight I plan to test the Gain Master and see if she can still hear me in the TV which will be a interesting test as well.

    Overall it's an interesting antenna. I took lots of close up pictures of the assembly and parts to include when I post my review. I think my first reports show from station to station depending on terrian and other factors antenna performance is very difficult to determine BUT I think once I can get 6 or more reports from different stations I should feel pretty confident in my final analysis of the antenna. I've already raised and lowered both antenna 3 times :) This next time around I hope to get all the stations on at the same time to save myself some work. Antenna doesn't require any tuning and was 1.1 SWR on my install. I did use a 2 x 2879 inline just to give it a try and the antenna didn't seem to have any problems handling the output.



    After I get reports from local stations the final testing I do will be to set up the antennas on the mast at a remote location and record the readings back at my home location so I can see for myself on the receive end.
     
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    Last edited: Apr 18, 2011
  2. Marconi

    Marconi Supporting Member

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    Very good report. I did a similar comparison, but mine was side by side. My results showed the GM ahead on signals just a little bit, less than .5 Sunit in this case however. I also saw the Imax produce TVI at my station while my GM showed none.

    BTW, my A99 & I-10K averaged the same signals at my GM at 7.3 in this series. I think I posted the report in my album.

    Looking forward to more reports.
     
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  3. hotrod

    hotrod Well-Known Member

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    good review. id would,ve like to seen the maco 5/8 u did a
    review on go against it.nice job
     
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  4. flatsideDX

    flatsideDX W9WDX Amateur Radio Club Member

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    Thanks for your efforts... interesting and not surprising. Thanks.
     
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  5. Highlander_821

    Highlander_821 Amour d'Ecosse

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    I think it should not be surprising for a signal that is 3DB higher than another to be louder and clearer. That's how it is supposed to work.
     
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  6. GnG8d

    GnG8d Well-Known Member

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    6.5-6.0=3.0?
     
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  7. Robb

    Robb Yup

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    Sure, each S-unit is supposed to be equivalent to 6db's.
    With one-half an S-unit difference (the difference between 6 and 6 1/2 S-units), that would be 3db's.
    When the human ear recognizes a 3db sound level change, it is perceived as twice as loud.
     
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  8. jazzsinger

    jazzsinger Bullshit Buster

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    if the s meter was theoretically perfect, then 6.5-6 does in fact equal 3.

    first you need to remember the 6.5 and 6.0 are s units not db,(db's are only used on s meters above s9,ie s9+10db = s9 x 10,the signal is 10 times stronger than an s9 one), therefore 1 s unit is theoretically equal to 6db ( never happens on 90 odd percent of ham/cb radios,more like 1 or 2 db per s unit but thats another story altogether), therefore if 1 s unit = 6db then .5 s units = 3db as highlander correctly pointed out.

    its about time the way s meters measure was clarified as far too many people talk in db's below s9 which just causes confusion and is completely wrong.
     
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    Last edited: Apr 19, 2011
  9. GnG8d

    GnG8d Well-Known Member

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    I knew that, I'm not sure what I was thinking. That's what happens when you try to be a smartass, you shit and fall back in it :unsure:
     
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  10. cbradiomagazine.com

    cbradiomagazine.com 2008 - 2014 / Pau Hana

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    Okay - I lucked out tonight and had stations to give me reports.

    Across the board 0.5 to 1 full S unit difference between the Imax and Sirio Gain Master with the Gain Master getting the nod.

    As for receive I still saw no difference between local stations on the incoming signals.

    SWR at 1.5 or lower from 25.500 all the way up to 30.000.

    Full write up to come but the antenna so far has definitely impressed me.
     
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  11. not quite

    About Decibels (dB)

    "Perception of Loudness (20dB = 4x)

    Interestingly, our perception of loudness is not the same as sound pressure level. Although the actual formulae
    is somewhat complex, as a rough rule of thumb, an increase of 10db SPL is perceived to be approximately twice as loud.

    Thus a 20 Db gain would seem to be about 4 times as loud.
    And a 40 Db gain would seem to be about 16 times as loud."
     
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  12. jazzsinger

    jazzsinger Bullshit Buster

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    i remembered reading similar in a hifi mag a few years back, but wasn't confident enough in its accuracy to contradict robs claim that 3db would give a twice as loud audio perception.

    one thing is for sure, a difference of .5 s units should make no perceivable difference to a radios audio output as the agc would limit any minor difference anyway.

    it could come down to just more excitement in talking on the new antenna giving a perceived voice increase, maybe even just from talking slightly closer to the microphone.

    nice link by the way booty, makes for some interesting reading.especially for those that believe antennas can have audio gain,lol.
     
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  13. mackmobile43

    mackmobile43 Jock Supporter

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    Hey CB, were you using AM mode? and has you neighbor heard you on the GM through her TV?
     
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  14. loosecannon

    loosecannon break on through

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    hey CB, i probably dont even have to ask, but are you telling the other stations which antenna is which?
    LC
     
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  15. MrSuburban

    MrSuburban Guest

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    Better watch out Booty, Mack will put you in his sig file for copying and pasting.


    But db in sound levels don't relate to db at RF levels someone can use a stock mic they are giving the same signal but sound rather low, they then change to a power mic the signal stays the same but now they sound louder. those db ratings are more along the lines of sound pressure changing. I don't think you can relate them to RF use.
     
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