[NLRS] 432 sprint and antenna stacking question

Sun Apr 25 14:03:03 EDT 2021

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 rovers 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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