Forgot to sign this--DUH! Saul K2XA
-----Original Message-----
From: Saul Abrams <sabrams@nycap.rr.com>
To: Stan or Patricia Griffiths <w7ni@easystreet.com>; Richard Karlquist
<richard@karlquist.com>; Towertalk (E-mail) <towertalk@contesting.com>
To: <towertalk@contesting.com>
Date: Monday, August 06, 2001 11:49 PM
Subject: Re: [TowerTalk] Wide spaced Yagis
>I have had a 4 on a 54 foot boom (actually 57 with a 3 foot tail for
>balancing) up for over 7 years. (and Fred, K2TR has a pair of 6's on a 54
>(57) which has been up at least 10-15 yrs). The boom is made cheap and
>easily with 20 feet of 3 inch irrigation tubing slipped over the ends of a
>20 foot piece of 2 1/2 inch aluminum emt (a little less than 3" OD). Just
>add a few inches of emt in the boom where you have to clamp down for an
>element. It has one set of vertical boom supports and is up 100 feet. We
>get a lot of snow in the Albany, NY area, but we don't get very much
icing.
>We also don't get many hurricanes or tornadoes, but we have seen our share
>of 50+ mph storms. It moves horizontally a little in the wind, but it's
>like the sappling bending with the wind while the mighty oak falls over.
>And yes, it is hard on the ego to say you "only" have a 4 el beam when you
>really have a 6 el boom! But it really plays!
>-----Original Message-----
>From: Stan or Patricia Griffiths <w7ni@easystreet.com>
>To: Richard Karlquist <richard@karlquist.com>; Towertalk (E-mail)
><towertalk@contesting.com>
To: <towertalk@contesting.com>
>Date: Saturday, August 04, 2001 1:44 PM
>Subject: Re: [TowerTalk] Wide spaced Yagis
>
>
>>
>>Richard Karlquist wrote:
>>
>>> I noticed in Chapter 8 of W2PV's Yagi book, he shows that for a 20 meter
>>> Yagi on a 54 foot boom, there is little difference in gain whether you
>use
>>> 4, 5, or 6 elements. What I don't understand is why you never hear of a
>54
>>> ft 4 ele Yagi, but 5's and even 6's are commonplace. This is kind of
>>> analogous to the question of why people bother with 4 element Yagi's on
a
>30
>>> ft boom when a 3 element on that boom has slightly more gain. I notice
>in
>>> the ARRL antenna book, there are a bunch of reference designs for Yagis.
>>> The 10 meter ones are more widespaced (in wavelengths) than the 20 meter
>>> ones. Why? Seems like they should be scale models of each other. Am I
>>> missing something here?
>>
>>Well, I don't think you are missing anything really mysterious here. 54
>foot
>>booms are hard to make strong enough to stay up through years of rough
>>weather. It has been done but it wasn't easy (or cheap). You could
>probably
>>make a boom 40 feet long for half the cost and with half the weight in
>>aluminum. On ten meters, a boom equivalent to a 54 footer on 20 meters is
>only
>>27 feet long . . . easy and cheap.
>>
>>Also, I don't think the information in W2PV's book is really widespread
>>knowledge among average hams, even those who have monoband Yagis, so it
>should
>>not be too surprising that is not applied often.
>>
>>I think the most import point, however, is "bragging rights". It is
common
>to
>>hear someone brag about the number of elements they have but rarely do you
>hear
>>them bragging about their boom length. Most hams simply "feel better"
>about
>>owning a 6 element 20 meter beam than they would about owning a 4 element
>20
>>meter beam regardless of the relative performance of the two. This is
just
>>"human nature" and has nothing to do with real antenna performance. K6ASL
>once
>>had a 5 element 20 meter Yagi on a 60 foot boom . . . very impressive. It
>was
>>up about a year until an irate neighbor cut the guy wires . . .
>>
>>Stan
>>w7ni@easystreet.com
>>
>>
>>List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
>>Trylon Titan towers, coax, hardline and more. Also check out our self
>>supporting towers up to 96 feet for under $1500!!
>http://www.anwireless.com
>>
>>-----
>>FAQ on WWW: http://www.contesting.com/FAQ/towertalk
>>Submissions: towertalk@contesting.com
>>Administrative requests: towertalk-REQUEST@contesting.com
>>Problems: owner-towertalk@contesting.com
>>
>>
>
List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 96 feet for under $1500!! http://www.anwireless.com
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
|