Confused with swr tuning

Discussion in 'CB Radio Forum' started by SenomarDTK, Feb 19, 2010.

  1. SenomarDTK

    SenomarDTK Bobtail Member

    11
    0
    Feb 14, 2010
    Celveland, Ohio
    0
    Alright so I got a hold of a buddy who has a workman swr meter, like the one I just ordered for myself, and went about tuning my radio and antenna since the antenna warning light would come on every time I keyed up and talked on every station.

    I understand how to actually tune it but what I'm confused about is it says to tune on 1,40, and 20. Well which one do I choose because they all read different from each other. I don't know how to really put it so I will just say what i did.

    Ok so I set my cobra to channel 1 and then set the swr meter needle to the "set" mark, then I fliped down the switch on the meter that will tell you your swr. I then changed the channel to 40 and the needle went more then it did on 1. So I trimmed the antenna down after a few more trys to bring 40 lower and I ended up with about 1.4 on 1 and 1.7 on 40 and I don't remeber what 20 was.

    So is that the correct way if checking and tuning? Do you set the meter to the set mark and then read your swr for 1 then switch over to 40 and try and match the two as close as possible with lowest rating, and if it's higher on 40 then on 1 you need to lower the whip? When I heard use channel 20 that confused me.

    Sorry I'm kinda all over the place, I'm still learing.
     
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  3. WA4GCH

    WA4GCH Road Train Member

    3,324
    577
    Aug 12, 2009
    Seminole Florida
    0

    FIRST .....

    A match of 1.7 to 1 is FINE ........ not great but ok ...

    OK tuneing .....

    IF your match is LETS SAY ..... 1.7:1 on ch 40 and 1.2:1 on ch 1 .....

    This shows your antenna is set to the low end of CB ( CH-1 ) so you need to bring the antenna frequency UP and you need to make the antenna slightly SHORTER ......

    Same would go if it was 1.2:1 on 40 and 1.7:1 on ch-1 you would need to SHORTEN the wip length.

    99.999% of radios are ok even at a 2:1 match but you start to lose signal that high ....

    VSWR ( SWR ) this is what losses look like ....

    1.0:1 loss = 0 percent 100% of power goes out the antenna
    1.5:1 loss = 4 percent 96% of power goes out the antenna
    2.0:1 loss = 10 percent 90% of power goes out the antenna
    3.0:1 loss = 25 percent 75% of power goes out the antenna

    NOW remember what does not go out comes BACK and your final has to handle it ......

    This is a simple overview I hope it help you .
     
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