[CQ-Contest] 4O3A Station rebuild

[Ranko Boca]

Hi Dave,

I was not 100% clear.

I have 3 towers, in triangle configuration.
Those are exactly the same configuration - Tribander stack of 3 larger/or 4
shorter TBs, plus 2/2 for 40M. It makes 3 directions on all bands from
40-10M with 3 towers only. Each antenna system is very serious, clean,
simple and predictable. It is my starting point, and we can accept it as
axiom 😁
My insisting on using 2L40 is due mechanical limitation I have on very
windy hilltop location. Simply, it is maximum size of antenna acceptable. I
know that 4/4 would be better, but it is not possible.
As I already have 3 towers, phasing two of them in USA or JA direction is
just an additional benefit. It will not make some huge improvement (take
off angle will remain the same), but can help. When use two of them in
phase, I will still have another two for other directions.

This is all about.

I am asking if someone made something similar already? Does anyone have
some experience/advice in choosing adequate tribanders with a bit longer
boom, what is necessary, if 40M will be optimized with 2L yagis?
I know about JK and Opti beam tribanders, but unfortunately, I don't have
EZ files, and it will take a lot of time to make modeling.

BTW, new 4O3A will be fully IP Station. Towers will be rotary, with a
mechanism for pulling tower up and down to the ground. So, 3 towers will be
parked on ground after contest and 4th tower will be used for remote
permanently.

It is a lot of work, and unfortunately I don't have to much of spare time
at the moment. So, help is welcome and I would not like to miss something
because I am in hurry. And I am tired of repair and climbing on towers.

73
Ranko


On Fri, Apr 20, 2018 at 11:51 PM, David Gilbert <xdavid at cis-broadband.com>
wrote:

>
> Ranko,
>
> I'm not sure I understand the appeal of the 4x 2L40 in H-frame
> configuration.
>
> 1.  Whatever gain you get from the horizontal phasing will come with the
> penalty of narrower beamwidth, and I'm not sure that's desirable for
> covering USA/VE/Caribbean.
>
> 2.  The theoretical maximum you can gain from the horizontal spacing is 3
> db and in practice would be less.  You could get most of that same gain
> with better pattern by simply using a single stack of two 4-element
> antennas on one tower.
>
> 3.  While beaming US/VE on 40m you run the risk of wasting whatever else
> is on the two towers if propagation happens to be better to some other
> location on those other bands.
>
> 4.  No matter how you try to optimize the spacing between the two towers,
> you will only get your best gain and pattern broadside to the two towers.
> If you try to swing both sides of the H-frame somewhere else you
> dramatically disturb the phasing that gave you your optimized gain.  A
> stack on a single tower holds its gain and pattern no matter where you
> point it.
>
> I'm probably missing something there, but it just seem like 3 rotary
> towers could be put to better use.
>
> In any case, 73 and best of luck on your rebuild!
>
> Dave  AB7E
>
>
>
> On 4/20/2018 7:10 AM, Ranko Boca wrote:
>
>> Hi Frank,
>>
>> nice to hear from you.
>>
>> I will have 3 rotary towers. On 40M I will have 2/2, plus four tribanders.
>> Towers are in triangle, and  will be able to turn two of them toward USA
>> or
>> JA. Want to have optimized 4x 2L40 in H frame configuration.
>> Exactly what you are saying, I have to look for 20M antennas, to fit this
>> optimized 40M distance of towers. Based on its boom length, I will look
>> for
>> adequate tribanders, or will decide to make it by my own.
>>
>> I hope it is more clear now?
>>
>> 73
>> Ranko
>>
>>
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