I use elements that are just over 65 feet each and am still working 
with the feed line length.  The chart on the internet gives some 
indication of lengths to avoid for the 80 and 40 meter bands and at 
present, the feed line is 102 feet,which is a recommended length for 
an 80 meter dipole however, I am not getting the tuning I expect on 
40 meters.  It is suggested that if the aerial won't tune on a 
particular band, lengthen or reduce the feed line by 1/8 wave length 
on the band that has the problem being tuned.  Interesting to see how 
it works out.

Although either 300 or 450 Ohm line is ok according to the articles, 
45 Ohm is said to be the best.

At 01:46 PM 3/05/2013, you wrote:
>That's always a good antenna!  How long are the elements.
> From what I read, a non-resonant feedline length is best.
>81 feet is a good length.
>I use a 80 meter double extended zepp here, fed with 450 ohm line through a
>4/1 balun in to either an external or internal tuner, depending on the band.
>I keep thinking of changing to a new antenna, then I work everything I hear,
>and ask why?  Its been up for 20 years, and I don't have an answer yet.  I
>hairpin the ends back so that the 178 feet of elements fit in a 44/112 feet
>lot.
>You can do the metric conversions.