I once was thinking about a deal like this. In my case I wanted
to put a 40m 4SQ inside my 80m 4SQ.
I did model it and saw a slight gain loss, think it was just
around 1 dB or so. I didn´t like that so I instead did put
the 40m 4SQ 300m/1000ft away from the 80m array. I´m sure
I could have bettered the situation by detune the 80m
antennas but I never did look in to that.
Gain loss was on the 40m array, the 80m didn´t get hurt.
/ Jim SM2EKM
Den 2020-01-28 kl. 17:43, skrev Mpridesti via Topband:
I had heard several negative mentions of placing an 80 m system inside a 160 m 4
square. At my place, I placed my 80 m 4 SQ northeast of my 160 m 4 SQ. Closest
elements are 75 feet away. Thinking I might get some negative interaction, I took
K3LR’s suggest of opening the feed points of the 80 m array while I am using
160. Built a relay box that shorted the cable ends (1/4 wave 75 ohm lines) so
electrically opened the feed points. Pretty simple.
Then spent a lot of time listening to WebSDR receivers in EU and switched that
relay box on/off to see if I saw any gain variation with the 160 antenna. I saw
no difference. However I have found a very slight improvement in F/B or F/S
when the 80 m array was open circuited (shorting relays engaged).
On the flip side of this, I have not seen any impact on 80 to the SW as I beam
through the 160 array. I have reference antennas on each band to check array
performance.
I continue to experiment on 160 - fun retirement project with lots of exercise!
Seems array interaction varies with different stations. I did not model my
setup.
Regards,
Mark, K1RX
On Jan 28, 2020, at 10:47 AM, Tree <tree@kkn.net> wrote:
W7IV asks:
" --I am planning a 160m TX 4SQ and another for 80M. Their centers are
going to be about 300' apart - is this far enough away? I have a little
bit of room to move them apart, but am lucky enough as it is to have the
space to get this. The closest verticals will be about 200' apart."
My experience supports the post K9YC just made that you don't need to worry
about this.
I used to have an 80 meter 4 square with my 160 meter TX antenna right in
the middle of it and
everything worked great. You can also see this in the ON4UN antenna
system.
73 Tree N6TR
On Tue, Jan 28, 2020 at 12:33 AM Paul F. Merrill <marinesvcs@gmail.com>
wrote:
HI - I have a couple questions -
--I am planning a 160m TX 4SQ and another for 80M. Their centers are
going to be about 300' apart - is this far enough away? I have a little
bit of room to move them apart, but am lucky enough as it is to have the
space to get this. The closest verticals will be about 200' apart.
--I'll be using N6BT vertical dipoles, so there will be no radial issues.
--WRT TX chokes - I'm worried about constructing feedline chokes for the
feedpoints and still having enough cable (.85vf) to get to the phasing
box. How have others done this? Do you have a choke and did you add it to
pre-cut phasing lines or did you wind the chokes and work backwards towards
the center to get the required electrical or physical length? Did you used
magnet wire for the choke instead of coax?
I've come across N6RO's helpful 2017 writeup of his 4SQ refurbishment and
it touches on these issues. Anyone else have time to share some wisdom?
Thanks in advance, Paul / W7IV
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