Topband: trying to tune up 80 meter 4-Square

Fri Oct 12 19:10:36 EDT 2018

You dont have to lower them but you need to short them to ground to make
them electrically invisible

On Fri, Oct 12, 2018, 6:07 PM Dick Green WC1M <wc1m73 at gmail.com> wrote:

> Interesting. This is not how I tuned my 40m 4-square, albeit with tubular
> elements not slopers.
>
> Anyway, my understanding is that you disconnect all four elements from the
> control box and measure at the feedpoint, not through the phasing lines. I
> did it that way and had no trouble tuning the elements. I did, however,
> tune them to a frequency that was something like 5% below the target
> resonant frequency. I can't remember the exact frequencies now, but I think
> I wanted the array resonant at 7.025 MHz, so I tuned them to about 6.700
> MHz. Might have been a little higher than that.
>
> I've not heard that you must lower the other elements to do the tuning.
> Certainly a pain with nesting tubular elements.
>
> 73, Dick WC1M
>
> -----Original Message-----
> From: Guy Olinger K2AV <k2av.guy at gmail.com>
> Sent: Thursday, October 11, 2018 11:29 PM
> To: David Raymond <daraymond at iowatelecom.net>
> Cc: w3ea at hotmail.com; terry burge <ki7m at comcast.net>; TopBand List <
> topband at contesting.com>
> Subject: Re: Topband: trying to tune up 80 meter 4-Square
>
> Essential point that might be missed: each one of the elements, one at a
> time, must be tuned independently with the other three elements down. This
> is the initial tuning. If when everything hooked up characteristics are OK
> then you’re done.
>
> Finish initial tuning and it's *not* OK? To slide the ARRAY center freq up
> or down, there are several methods:
>
> 1) Redo the initial one at a time tuning with an opposite-to-the-error
> adjustment to the one at a time tuning target frequency.
>
> 2) make *small*  identical wire length changes to all four elements at the
> same time.
>
> 3) If you're an engineer and have the equipment and design software,
> redesign the box to work with what you have. ☺
>
> Just remember that the elements of a four square are very heavily coupled
> to each other, regardless that all are driven from the control box. The
> final result is a complex function of the driven current AND the effects of
> the heavy mutual coupling between elements.
>
> 73, and good luck,
>
> Guy K2AV
>
>
>
>
> On Thu, Oct 11, 2018 at 8:15 PM <daraymond at iowatelecom.net> wrote:
>
> > Yes, install ONE sloper. . .measure and cut to resonance.  Duplicate that
> > measurement for the other three.     73. . .Dave, W0FLS
> >
> > -----Original Message-----
> > From: Wayne Kline
> > Sent: Thursday, October 11, 2018 6:03 PM
> > To: terry burge ; topband at contesting.com
> > Subject: Re: Topband: trying to tune up 80 meter 4-Square
> >
> > Terry,
> >
> >
> >
> > I assume  you only  installed ONE sloper and made your measurements ?
> >
> >
> >
> > With all 4 installed  there is  way to much mutual  coupling to get a
> > meaningful reading.
> >
> >
> >
> > If your  readings were from only ONE antenna tuned with a length of 50
> > OHM cable at it’s feed point and trimmed to your desired  freq. and
> > that FREQ will rise about 80 to 120 KC when the 4 are installed .
> >
> >
> >
> > Wayne W3EA
> >
> >
> >
> > Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for
> > Windows
> > 10
> >
> >
> >
> > ________________________________
> > From: Topband <topband-bounces at contesting.com> on behalf of terry
> > burge <ki7m at comcast.net>
> > Sent: Thursday, October 11, 2018 6:11:37 PM
> > To: topband at contesting.com; terry burge
> > Subject: Topband: trying to tune up 80 meter 4-Square
> >
> > Hello Guys and Gals,
> >
> >
> > Recently Tree did some work for me and one of the things was to put up
> > the Comtek 80 meter 4-Square switching unit and a couple of pulley
> > setups for my raising of the 80 meter slopers. Lately I've been
> > chasing my tail around to get them dipped in around 3700-3750 Khz.
> > Been adding or subtracting length of the slopers to bring them into
> > resonance but it seems the more I work at it the worse things get.
> > Today I dropped back to punt by rechecking my Rig Experts AA-170 with
> > a 50 ohm load just to make sure it read right...it did.
> >
> >
> > The sloper dipoles are MFJ 1779B's 'trim to length' except one I had
> > to rebuild with a hy-que center SO-239. RG-213 from the switching unit
> > to the Rig Expert and when put together using a long run of LMR-400
> > about 175-200'
> > back to the shack. 75 ohm DXE foam RG-11/u coax quarter wavelength
> > stubs from switching unit to each dipole center. Each 75 ohm stub has
> > multiple ferrite snap on's 5 or 6 to form current baluns.
> >
> >
> > Here is an example. SE sloper, read SWR of 3875-3850 Khz of 1.0:1 in
> > the shack on Elecraft W2 wattmeter. 3799 Khz SWR 1.3,  3775 Khz 1.4,
> > 3750 1.5,
> > 3725 1.5, 3700-3650 1.7...Added 19" each end and it seemed to read
> > close to the same resonance!  Added 24" more each end and this time
> > used the Rig Experts to check it out. Got two dips but not even where
> > I was expecting them
> >
> >
> > Resonacne 4680 Khz    SWR 1.16
> >
> > RL 23.3 dB          |Z|   57.4 ohm
> >
> > R:  57.5 ohms      X: 10.7 ohm
> >
> >                              C:  52000 nF up and down
> >
> >
> > R::  57.9 ohm         XLL  -4878 ohm
> >
> >
> > second dip at 2169 Khz      SWR  1.07
> >
> > RL 28.0 dB           |Z|  46.5 ohms
> >
> > R:  46.5 ohms       x:  0.2/0.4 ohms
> >
> > L:  2.2 nH
> >
> > R::   46.4 ohm        X||  (infinity or very high)
> >
> > L:||  same infinity
> >
> >
> > And the frequency where I was trying to drop down from when I begain
> > this morning....
> >
> >
> > 3860 Khz
> >
> > resonance now 3984 Khz   SWR  1.8:1
> >
> > R:  10.9 dB     |Z|  27.9 ohms
> >
> > R:  27.9 ohms    x: -0.1
> >
> >                            c: infinity
> >
> > R||  27.8 ohms    X||  -48000 up and down
> >
> >                             C||  8pF
> >
> >
> > How can I add almost 4' of wire on each end and not drop the resonance
> > down a couple hundred Khz? What is with the two dips way above and
> > below where the 128' sloper should be resonating? That is an
> > approximate length since by this time and several days of adjusting
> > I'm not sure what each dipoles length are. Since I have a 40 meter
> > dipole near the slopers I tried raising and lowering about 10-15' up
> > and down but it did not seem to change much.
> > I'm beginning to instinctively cringe each time I have to tune up an
> > antenna because this is what I know I'm in for. Especially with
> > dipoles!
> >
> >
> > After all this I just made another run of the SWR across the band with
> > the SE sloper.
> >
> > 3550 Khz  1.7:1 ,   3600 Khz  1.7 ,  3650  2.0 ,  3700  1.7 ,  3750  1.7
> ,
> > 3795  1.5  , 3825  1.3 ,
> >
> >
> > 3850  1.1  ,   3875  1.0  ,   3900  1.1 ,  3925  1.3 ,  3950  1.5 …..see
> > what I mean?
> >
> >
> > Terry
> >
> > KI7M
> >
> >
> >
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