Topband: trying to tune up 80 meter 4-Square

[daraymond at iowatelecom.net]

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



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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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