Jim,
you are right, it is not a balun, it is a common mode choke, you can
see it this picture from an Vertical I had (
http://paginas.fe.up.pt/~ee04056/CT1ILT/pics/tvertical/version1/thumbs/15.JPG
)
maybe we can try a QSO tonight?
Filipe CT1ILT
Citando Jim Brown <jim@audiosystemsgroup.com>:
> On 1/26/2012 1:48 PM, ct1ilt@sapo.pt wrote:
>> I measured the impedance at the base and it is Z = 23 + 9j with VSWR
>> of 2 to 1.
>
> If that is a good measurement, i wouldn't bother with a matching network.
>
>> The VSWR after 50m of coaxial cable and a home made 1:1 balun (made
>> with coax) is 1.7 to 1.
>
> What do you mean by "balun?" Did you wind turns of the coax around a
> ferrite core? That is NOT a balun, it is a common mode choke. Some
> people who don't know better call it a "current balun." A common mode
> choke like this does NOT affect the VSWR or the loss in the coax (except
> for the small additional length of coax it takes to wind the choke).
>
> Based on your VSWR measurement and your impedance measurement, I'd say
> you're in pretty good shape, at least from the perspective of matching
> to the TX. Good luck in the contest.
>
> 73, Jim K9YC (California, Near SF)
>
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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