[NLRS] Yagi Spacing Q.. - MORE questions

[KB0NLY]

Yes, your correct, they are end mounted.  And I would think there would be 
less interaction problems with the mast as well.  In my case they will be 
mounted on a crossboom to use less vertical space on the towers mast.  So 
there will be a mast perpendicular to the elements but only on one side, 
well a few inches past the clamp on the other side.

Never tried one of those dualband yagi's but often wondered the very same 
thing myself.  I also wondered how they made them work with a single input, 
looks like two specific lengths of coax to a "T" and then you connect the 
feedline to that.

I collected these Yagi's over time, the 124WB was a cheap eBay find, brand 
new in the box, and the A449-6S was a used one I got for next to nothing. 
So I figured I would try them for local FM use, maybe get into a few distant 
repeaters a bit better, rather than buy a new dual band one for the same 
purpose.

73,

Scott




>
> Not to questions Jim's response...BUT, and _particular_ to Scott's
> specific antennas.
>
> Since the 124WB and A449-6S are end mounted designs...wouldn't there
> be 'less' worry about such interaction with the mast and/or coax?
>
> In Cushcraft (Laird?) pictures (with the antennas by themselves), they
> are shown with a mast (presumably metal) only inches behind the
> reflector.
>
> ALSO, Cushcraft (Laird?) makes (made?) the A2706S and A27010S Dual
> Band Yagis where elements are on the SAME boom, essentially 'minimal'
> spacing between the two antennas.
>
> So I guess my questions would be...
>
> 1. IS a "rear" mast out of the 'capture area' for the antenna or not?
>
> 2. Has anyone done an evalation of those Dual Band Yagis? How DO they
> perform with, basically, TWO antennas on the same boom? Probably
> seeking a "more thorough" assessment than "just" max. forward gain as
> is typically done at conference antenna ranges, e.g. 'cleanliness' of
> pattern, any "odd" nulls in the forward direction, and the like.
>
> 73, JK
> ----- Original Message ----- 
> From: "Jim Froemke" <jim.k0mhc at earthlink.net>
> To: "'KB0NLY'" <kb0nly at mchsi.com>; "'NLRS'" <nlrs at mailman.qth.net>
> Sent: Thursday, October 23, 2008 11:00
> Subject: RE: [NLRS] Yagi Spacing Q.. - response
>
>
>>
>>
>> Hi Scott
>>
>> For your application (vertical polarization) a bigger issue is the
>> proximity of each antenna to the vertical metal mast. For best
>> performance
>> you'll want to keep the vertical metal mast OUTSIDE of the capture
>> areas of
>> both antennas. This means your horizontal spacing along your
>> horizontal mast
>> between each antenna and the vertical mast should be AT LEAST 1/2
>> the
>> diameter of each antenna's capture area.
>>
>> You could use a non conductive vertical mast (if it's strong enough)
>> but when your coax makes a 90 degree angle to descend down the
>> vertical mast
>> it also becomes a vertical conductor located on the vertical mast
>> between
>> the two antennas so you'll still have this problem.
>>
>> 73, Jim
>> K0MHC
>>
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