[AMRadio] new antenna and matchbox a bust.


John Lawson jpl15 at panix.com
Mon Jan 29 12:33:25 EST 2007



On Mon, 29 Jan 2007, Brett gazdzinski wrote:

>
> Today I put up about 50 feet each side, up about 35 feet,
> fed with 40 feet of open wire line.
> Coming into the house I used 2 RG214 runs, with the shields
> tied together at the ends, into the Johnson antenna tuner.
>
> A worse working thing I ever put up.


    Probably. W/out going into a lot of math - 50' is quite short, and not 
near a multiple or fraction, of the bands you mention.

    "Fed with open wire line": Fed in the center?  What Z is the feedline? 
What Z is the feedPOINT of the antenna at the hieght and ground 
conditions?

  Then you mention RG214 - how does the balanced(?) 'open wire line' make 
the transition to the coax? if the feedline is 450 ohms, you need a 4:1 
Balun at that point in your System.

    Oooh, wait - do you mean you ran *two parallel runs of coax* 
side-by-side, "with the shields tied together at the ends"...?

    Umm - that just won't work at all, I don't theenk.....


   T'were Moi, I'd extend the antenna to around 62 feet each leg - then run 
one stretch of feedline from the antenna's feedpoint into the shack and 
the tuner.  You might want a balun at the antenna feedpoint if you use 
your (SINGLE RUN!) RG214, or, run the ladderline into the shack (keep away 
from parallel metallic objects) and into the BAL outputs of your tuner.


   Good luck!


  Cheers

John
KB6SCO
DM09fg




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