Topband: cutting coax stubs for 80 meter 4-square

[Joel Harrison]

Hi Terry,

I replaced the 1/4 lines on my 80 meter 4 square this past fall and used
my AA-170 to set the length with no problem.

Just select "all" for the mode and set the freq you're aiming for and then
trim the line until X equals zero with the far end open. Should work fine.
I always calculate the length x VF then add a few feet to start.

73 Joel W5ZN


> Hi guys and gals,
>
>
> I have got DX Engineering 75 ohm foam coax to make the stubs/feeders for
> my Comtek 80 meter 4-Square and am finding some difficulty. Neither my
> MFJ-259B nor my Rig Experts AA-170 seem to indicate a 1/2 WL at 7500 KHz
> or a 1/4 WL at 3750 KHz? Or any frequency up or down from there. Seems to
> me the last time I did this a few years ago I didn't have a problem
> getting a 1/2 WL dip indicating a resonance location. But now I just don't
> get any indication of a resonance.
>
>
> DX Engineering said they had got some 75 ohm foam coax that instead of
> 0.84 VF was more like 0.80 down to 0.76 VF. But checking all the way down
> to 6000 KHz on 40 meters or 2500 KHz on 80 meters fails.
>
>
>  My test is to use either antenna analyzer with a PL-259 installed at one
> end and an open or a short at the other. I started with 57'7" of coax.
> Tried both with the coax in a roll and strung out. What am I doing wrong?
>
>
> Terry
>
> KI7M
>
> 😞
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