The bigger antenna shopuld be on top.
Why? Because at the lower frequency the extra 15 feet would be maybe 3 db
gain at 6 meters where its maybe .5 dg gain at 432 because its allready
several wavelengths up. Im sure this is exagerated a bit. Also with the 6
over the 2 picture the extra ground plane above the antenna where some
energy is sent into space at that angle if not for a overhead reflector.
> [Original Message]
> From: steve d <kc8qvo@yahoo.com>
> To: <vhfcontesting@contesting.com>
> Date: 10/28/2005 9:50:23 AM
> Subject: Re: [VHFcontesting] VHFcontesting Digest, Vol 34,Issue 22
(stacking distance 50, 144, 432, 144/440)
>
>
> OK, now I am getting confused. I am hearing a LOT of different things
here. Some of you say to stack the 144 beam above the 50 beam at the
stacking distance for 144... That doesnt make sense because the stacking
distance for 50mHz is MUCH more than at 144. Using the 1/2wl theory the
stacking distances between the beams should be:
>
>
>
> 9.36' between 50mHz and 144mHz
>
> 3.25' between 144mHz and 432 mHz
>
> And going by the lowest frequency on the dual band beam (144mHz) - 3.25'
between that and the 432mHz beam.
>
> This comes out to a total of 15.86', then you have to add in some length
to extend through the thrust bering to the rotator. I am going to estimate
the TOTAL length at 20 feet. Does this all sound correct? I want the beams
to be as efficient as possible.
>
>
>
> Also, what does everyone reccomend as a mast? Array Solutions sells some
REALLY NICE PE certified masts, but they are VERY expensive. I was
thinking about going to the plumbing supply store and getting a 2"
galvanized steel pipe. Would this work? What should the wall thickness be?
I calculated the windload at 6.675sq feet, so there isnt a whole lot of
loading there.
>
>
>
> Thanks for everyones help!! I hope to get back on the air this weekend as
the VHF/UHF bug is biting pretty hard!!
>
>
>
> Steve, KC8QVO
>
>
>
> Steve, KC8QVO
>
>
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