[TowerTalk] Extended Double Zepp Problem

Thomas R. Williams n2cu@buffnet.net
Fri, 16 Oct 1998 10:12:14 -0700


Greetings,

I have installed EDZ's for 80m and 40m at right angles on my tower at
40' using the formulas supplied by two sources (leg length = 630/f, 450
Ohm ladder line length = 135/f). Attaching an MFJ-249 at the ladder line
(no balun) indicated an SWR of >3:1 on the 80m EDZ and I couldn't even
get the meter off the peg on the 40m version. 

I understood from articles by VE3ERP and the ARRL Handbook that with the
proper ladder line length, a 50 Ohm match could occur. A transition to
coax could be made for the run back to the shack with no tuner
necessary.

Dimensions are as follows:

                             80m (40m)

	169' (85' 1")				169' (85' 1")
________________________________  ________________________________
                                ||
                                ||
                                ||
                                ||
                                || 38' (19'2")
                                ||
                                ||
                                ||
                             1:1 Balun 
                                 |
                               Coax

Am I mistaken about not having to use a tuner, or is one always
necessary? Should I be using a 4:1 balun? Any help would be appreciated.
In the mean time I guess I'll go outside and put up my GAP vertical for
low band work.

73,
Tom N2CU

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