[NLRS] 432 sprint and antenna stacking question

Mary Brown maryalanab at gmail.com
Sun Apr 25 15:24:10 EDT 2021 

I don't want to go wide on that tower, house bracketed rohn 25... 2 meter
tower is loaded with 4 2m12's... going to add a third tower off the second
story deck for 6m and 222, gains me about 20 feet of separation form 432 and
1296 that will be on the current rohn 25(has 6 and 432 right now, moving 6m
to make space... ) if I do that I will have 6' of space between 432 and
1296, 30 feet to the 2m array, 20 feet to 6m and 222... not optimum, hard to
space out towers on a small lot when guy wires are something I want to
avoid. 

Power levels
6m 100 watts for now, working on a 350 watt amplifier
2m 1kw
1.25m 7 watts for now... looking at amplifier options in the 250 watt range,
must be solid state(back says NO to heavy iron tube pwr supplies!)
70cm 750 watts
23cm 500 watts

Might add 902 down the road if I can do it really really cheap... 

Link to pic with changes, the right hand roof line is too low to bracket a
tower to, plus I now have a steel pole garage 10 feet to the right of it
with a 25 foot roof peak.

https://i.imgur.com/FaAzodM.jpg

Mary
W0AAT

-----Original Message-----
From: nlrs-bounces at mailman.qth.net [mailto:nlrs-bounces at mailman.qth.net] On
Behalf Of scsueepe at mtcnet.net
Sent: Sunday, April 25, 2021 1:03 PM
To: NLRS at mailman.qth.net
Subject: Re: [NLRS] 432 sprint and antenna stacking question

Mary, have a look at this link on my website.. where I close spaced lots of
antennas.  Worked like champ and might give you some ideas.

http://km0t.com/pages/june2001.htm


73

Mike - KM0T


-----Original Message-----
From: nlrs-bounces at mailman.qth.net <nlrs-bounces at mailman.qth.net> On Behalf
Of Jon Platt via NLRS
Sent: Sunday, April 25, 2021 12:48 PM
To: nlrs at mailman.qth.net
Subject: Re: [NLRS] 432 sprint and antenna stacking question

To add to this, Rovers have been close spacing yagis & loopers for some
time.  Kent, WA5VJB, has presented at Central States on the effects on
antenna gain due to close spacing of antennas.  His finding is that there is
very little affect on gain, but that pattern can be affected.  We hear from
EMEers how such close spacing affects their ability to hear because the
antenna pattern gets hosed by interaction, while rovers who generally don't
care about pattern that much have had great success with close spacing.  So
it depends.  If you want to do EME, closer spacing should be avoided in
order to keep your antenna pattern as clean as possible.  Also, as someone
else commented on, close spacing can blow the front end.  This has happened
to me as a 100 watt rover when I got the driven elements really close, like
under a foot or so.  From roving, I've found that keeping a physical
distance of several feed works fine, and to keep harmonically related
antennas farther away.   Some ro
 vers and fixed stations simply key all their preamps at once regardless of
what band they are on in order to protect them.  Myself I have found that
this isn't necessary but then I'm only running about 100w when roving.
73, JonW0ZQ


-----Original Message-----
From: Bill ND0B <nd0b at ockert.us>
To: 'Mary Brown' <maryalanab at gmail.com>; 'NLRS' <nlrs at mailman.qth.net>
Sent: Sun, Apr 25, 2021 11:35 am
Subject: Re: [NLRS] 432 sprint and antenna stacking question

Hi Mary,

I used this is guidance when I put up my antennas.    

https://directivesystems.com/information/tech-notes/multiple-loop-and-yagis-
on-one-mast/

I have 6m, 222, 2m, and 432, in that order, stacked on the same mast that
extends about 15 feet above the tower.  It is definitely not optimal but
does provide enough isolation that I have yet to pop a preamp.    Part of
the spacing was mechanical issues, the 6m and 2m antennas both have guying
systems so the 222 antenna was placed just above the 6m guy mount, the 2m
was spaced down from the top such that there was room for the 70cm antenna
above it.  This arrangement did not flagrantly violate any of the guidance
DS offered and it seems to be working as I have yet (emphasized) to pop a
preamp.  

73 de Bill ND0B



-----Original Message-----
From: nlrs-bounces at mailman.qth.net <nlrs-bounces at mailman.qth.net> On Behalf
Of Mary Brown
Sent: Friday, April 16, 2021 4:30 PM
To: 'NLRS' <nlrs at mailman.qth.net>
Subject: [NLRS] 432 sprint and antenna stacking question

I will be on for the sprint from en24gp.

 

And question on stacking. I need to put 222, 432, and 23cm on one tower.

 

Antenna and half stacking distance

222-10ez 3' 3" half stacking distance

432-9wl 3' half stacking distance

23cm35x4 on an H frame 1' 2 1/2" half stacking distance

 

Thoughts were 222 on the bottom 2' above the tower

Then 23cm35's 4'5" above that

Then the 432 antenna 4'2" above those

 

According to DX Engineering mast load this will survive 120mph. 

 

Thoughts? Going to be running power on 432 with 750 watts and 23cm with 550
watts,  so interactions? Preamp issues from the RF fields? Preamps will be
below tower top so it will just be whatever the antenna picks up from the
other bands.

 

Would love to space this more but this is going on a bracketed Rohn 25 on
the side of the house. right at max wind load. 

 

Mary

W0AAT

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