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@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@contesting.com> on behalf of terry burge
<ki7m@comcast.net>
Sent: Thursday, October 11, 2018 6:11:37 PM
To: topband@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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