Mark,
You could try rotating the 1/4 wave lines (i.e. remove the line that was
driving the NE element and install it in place of the line that was
driving the NW element, and so on) to see if the signal drop follows the
position of the 1/4 lines or stays in in the SW direction. If the
problem persists in the SW direction, the the problem is either in the
Comtek box or with one of the elements. If the problem follows the
lines, then you probably have a bad line. Similarly, you can "rotate"
the Comtek box (connect coax coming from the NE element to the NW
element port, coax coming from the NW element to the SW element port,
and so on). If the problem follows the "rotation" of the Comtek box,
then the box is likely the source of the problem.
BTW, when you measured the 1.87:1 VSWR on one line versus 2:1 VSWR on
the other three, were you using a 50 ohm dummy load to terminate the
lines or the corresponding array elements?
73, Mike W4EF...................
On 11/2/2021 11:41 AM, Mpridesti via TowerTalk wrote:
My 80 m 4 SQ seems to work well in 3 positions. To the SW the signal drop in
the favored direction where the other 3 directions appear to work well.
SWR measurements seem normal around 2:1 at the end of the 1/4 wave 75 ohm lines except
one which is 1.87. Haven’t made loss measurements yet but I suspect the lowest
SWR line is the problem (low reading due to higher than normal loss making it the
suspect line).
Has anyone else experienced this type of behavior? Also the suspect line is the NW element
and the direction which has the problem is SW. Does this make sense? Effectively this lossy
element is the other half of the “driven element “ if you thought of the 4 sq
as a 3 el vertical beam.
Keeping with this concept, one would think the NE direction would have similar loss but it
doesn’t (or it’s not noticeable).
Regards,
Mark, K1RX
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