Tom Rauch wrote:
> I spoke against including a "resonance" function in the
> MFJ259. The reason is you cannot measure resonance of an
> antenna through a length of feed cable unless you know a
> great deal about the feedline.
>
> All those who think they are measuring resonance of an
> antenna when they measure zero X at the end of a
> transmission line without understanding special
> qualifications are assuming incorrectly. The only exception
> would be if the antenna was 50 J 0 at resonance, in which
> case the feedline could still introduce false zero X
> crossings.
------
This may be a case of a simple ommision on Tom's part or an assumption
that the rest of us know as much as he does.
However, if you use an electrical 1/2 wave line connected to the
antenna, the impedence of the antenna will reflect exactly at the MFJ.
As a matter of course, I keep good quality RG58 lines for all bands
just for that purpose. I might also add that it does not matter what
the characteristic impedence of the test line is. Also, while
constructing it, if you use a high multiple ( such as
140 mHz ) for a 40 meter line, you get a much sharper dip.
73
Ed
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