Thanks for the input, Dave.
I have an idea that my broader bandwidth is due to the
fact that my tower is insulated from the 60 foot point on up.
Someone could model this and see.
> I have a K8UR configuration 4 square on 80 mtrs which hangs off the 120' guy
> ring on my rotating tower. Based on my own experience, I'm suspicious of
> your SWR readings. The antenna simply cannot be that flat over a 100 KHz
> Also, when I was building mine I was anticipating an upward shift in
> resonance due to the mutual coupling of the four antennas. On the K8UR
> configuration, this does not happen. . . so you don't want to follow the
> general rule of thumb of starting out with antennas that are low in
> frequency. I cut my dipoles by the formula for 3.490 thinking the array
> would shift upward by 5% or so. I installed the first one and it was
> resonant at 3.490 per the formula. I added the other three. . . the
> resonant frequency of the array didn't change (measuring resonance as the
> minimum power dumped to the dummy load). I'm getting 2-3 watts into the
> dummy load with about 90 watts delivered to the Comtek box. . . but
> certainly not over a 100 kHz window. I'd have to say something else is
> influencing your readings.
> 73 and good lowband DX this season to all. . . Dave
> -----Original Message-----
> From: Phil Clements <email@example.com>
> To: firstname.lastname@example.org <email@example.com>
> Date: Monday, September 27, 1999 12:50 PM
> Subject: [TowerTalk] Tuning the K8UR-Style 4-Square
> >On page 11-79 of ON4UN's 1999 book, Mike, K4PI
> >uses vacuum relays to switch about 6 feet of wire on
> >each of his 4 dipoles at the ground level to QSY his
> >K8UR-style 4-square from the SSB DX window to the
> >CW DX window on 80m.
> >Since my version was resonant when installed at 3622 khz,
> >I cut 5 feet off the bottom end of each dipole to QSY the
> >array to 3770 khz. My "window of resonance" on this array
> >is 100 khz. IOW, the power to the dummy load on the Comtek
> >box is zero from 3713 to 3813 khz.
> >All this sounds really good, but could this be good VSWR for
> >all the wrong reasons? I now no longer have 4 symetrical dipoles,
> >but 4 off-center-fed dipoles. What has this done to the pattern
> >and or the Comtek box? Has anyone run any modeling on a
> >situation similiar to this one? Please share any of your experiences.
> >Phil, K5PC
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