Allen,
To get useful stacking gain from a 4 element SteppIR and a small 10 meter Yagi,
you would need to install you 10 meter beam at least 18-20 feet above the
SteppIR. In all likelyhood, if your tower is not strong enough for a MonstIR,
its also not strong enough to be extended 20 feet without significant risk of
tower failure.
Your tower might be strong enough to safely install a second small Yagi five
feet above your SteppIR (that analysis is up to your PE). That would give you
the flexibility to point in a different direction if that's valuable to you.
Don't set the the SteppIR on the same band, because the short spacing distance
would degrade both antennas when they're tuned to the same band.
Your initial post did'nt mention that you're planning to add a tall mast and
additional antennas to a crank-up tower. Adding a tall mast and heavy antenna
loads to a crank-up is risky business, not uncommonly resulting in tower
failure. Engineering analysis of your new installation is essential to its
safety and endurance.
73!
Frank
W3LPL
---- Original message ----
>Date: Mon, 14 Aug 2006 21:34:59 -0500
>From: "Allen R. Brier" <britech@earthlink.net>
>Subject: Re: [TowerTalk] Mast size/material for stacking not-so-big beams
>To: "'Al Williams'" <alwilliams@olywa.net>, "'Tower Talk Reflector'"
><towertalk@contesting.com>
>
>10 meters is my favorite band (when the spots are there). My tower is a
>crank-up, so I don't know if I can mount the mono at a lower height. I'll
>have to look into that later. However, if I could feed the SteppIR and the
>mono in and out of phase, how much additional gain would I get? A SteppIR
>Monstr is too big for the tower. I am also considering adding the 30/40
>meter dipole to the 4-el. Advice??
>
>Allen Ross Brier, N5XZ
>
>-----Original Message-----
>From: Al Williams [mailto:alwilliams@olywa.net]
>Sent: Monday, August 14, 2006 10:26 AM
>To: 'Tower Talk Reflector'
>Subject: Re: [TowerTalk] Mast size/material for stacking not-so-big beams
>
>What is your antenna objective?
>
>An alternative approach that would seem very good is a Steppir Monstr just
>above the tower and then another Steppir above on the mast--possibly a 4 or
>3 or 2 element that could be rotated independently from the Monstr?
>
>k7puc
>
>----- Original Message -----
>From: "Allen R. Brier" <britech@earthlink.net>
>To: "'Tower Talk Reflector'" <towertalk@contesting.com>
>Sent: Sunday, August 13, 2006 11:05 PM
>Subject: [TowerTalk] Mast size/material for stacking not-so-big beams
>
>
>> This is a two part question:
>>
>>
>>
>> I am planning to install a 4-el SteppIR at 70 ft and possibly another HF
>> beam above it in the future. One plan is to install a 10-Meter monobander
>> in
>> a few years when the spots come back. Another is to install a 2 or 3 el
>> 40-meter monobander.
>>
>>
>>
>> 1. How much benefit would I get mounting the 10-meter mono above the
>> SteppIR on the same mast and how far should I space it if I do it.
>> 2. What size and material mast should I use if I mount a 40-meter beam
>> above the SteppIR? (Material / length / wall thickness, etc)
>>
>>
>>
>>
>>
>>
>>
>> Allen Ross Brier, N5XZ
>>
>>
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
>
>_______________________________________________
>
>
>
>_______________________________________________
>TowerTalk mailing list
>TowerTalk@contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|