My 40 meter Cuscraft D40 is only 4 feet above the Force 12 C3S tribander.
I could have explained it better, the D40 is 90 degrees off of the C3S, the D40
is in line with the boom of the C3S.
I would recommend you email Force 12 and ask them about your proposed stacking.
They are very knowledgable
about stacking their antennas (as they should be)
I saved myself a lot of testing thanks to their help.
73,
Bob
K6UJ
On Aug 29, 2011, at 6:37 PM, Felipe J. Hernández wrote:
> Really?
>
> So no 90 deg off for that combination? May I ask how far where they apart?
>
> I guess is the right approach to then model the antennas exactly..
>
> I liked this explanation from Bob...
>
> I have a Cushcraft D40 4 feet above a Force12 C3S tribander.
> The D40 is aligned parallel with the boom of the C3S.
> I have zero interaction between the two antennas.
> I called Force12 and asked what they recommend for spacing before installing
> the antennas and
> they said they recommend 4 feet wth the dipole parallel with the boom of the
> C3S. Said this will give
> negligible interaction (as I have found).
> I would recommend calling or emailing them to discuss your planned
> installation and question.
>
> As I understand the stacking situation, the current drop of multiband yagis,
> like the Force12 series,
> have all the elements electrically insulated from the boom which provides
> very nice stacking possibilities
> with minimal interaction. The older design tribanders like the KLM KT34's
> had the parasitic elements
> electrically attached to the boom and it is almost impossible to achieve a
> low interaction regardless
> of height/orientation.
>
> 73,
> Bob
> K6UJ
>
>
>
>
> On 8/29/2011 9:03 PM, john@kk9a.com wrote:
>> I have modeled 20m and shortened 40m beam interaction and with my antennas
>> and the interaction was very minimal when pointing the same direction and
>> very noticeable when pointing 90 degrees apart. The antennas in your
>> example may react differently, but I would recommend trying the same
>> direction first.
>>
>> John KK9A / P40A
>>
>>
>> To: towertalk@contesting.com
>> Subject: [TowerTalk] 40 and 20 at 15 ft apart
>> From: "Felipe J. Hernández"<fhdez@vpnet.net>
>> Date: Sun, 28 Aug 2011 19:13:31 -0400
>> List-post:<towertalk@contesting.com">mailto:towertalk@contesting.com>
>>
>> Guys,
>>
>> Theres a great benefit from turning the antennas 90 deg off.
>> but Ive heard that, when you have a 40 and a 20 on the same tower, the
>> interaction
>> is never dissipated by the 90 deg offset.
>>
>> Is that true?
>>
>> Thinking of setting up a xm240 with a 3 or 4 el force 20 mtr monobander
>> abt 15 ft apart..
>>
>> Thanks
>>
>> Felipe
>> NP4Z
>>
>> _______________________________________________
>>
>>
>>
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>>
>
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