[TowerTalk] Single tower and 3 monoband yagis - "Christmas three"

[Joe Subich, W4TV]

> Given the short distance between top and bottom antennas, is there a
> benefit to this kind of array vs. interlaced monobanders on a common
> boom?

That's exactly the reason I asked if the monobanders had been optimized
for stack use.  Study after study shows the 15 meter antenna is badly
impacted in these "close" stacks - even if the SWR stays fairly close
to nominal.  The 15 will affect the 10 but not as badly as the 20
affects the 15.

Years ago I had a 204/155/105 stack put up with Hy-Gain's recommended
spacing (I think it was 7' from 20 to 15, 5' from 15 to 10) and the
15 never really worked as well as it should have.  I moved the 204 to
another tower (stacked it with a second 204) and brought the 15 down
so there was a full 12' between 155/105 and both antennas performed
a lot better.  Knowing what I do now, I should have found a way to get
the 105 a full 16' above the 155 ... or optimize the 105 for the
presence of the 155.

73,

    ... Joe, W4TV


On 2014-12-11 2:49 PM, Kelly Taylor wrote:
> Can I step back and ask a bigger-picture question?
>
> Given the short distance between top and bottom antennas, is there a benefit
> to this kind of array vs. interlaced monobanders on a common boom?
>
> In Fudo's case, perhaps he is using existing antennas and isn't in a
> position to replace them with something such as a long-boom F12 antenna, but
> in a from-scratch installation, is there any reason to move to the
> mechanical challenges of stacking antennas like this so close together vs.
> using just one antenna?
>
> 73, kelly
> ve4xt
>
>
> On 12/11/14 1:35 PM, "n8de at thepoint.net" <n8de at thepoint.net> wrote:
>
>> I agree with Joe, W4TV, but, would add the comment:
>>
>> PUT THE 20M monobander on TOP of the stack .. that is .. invert it,
>> with the 10m on the BOTTOM.
>>
>> 73
>> Don
>> N8DE
>>
>>
>>
>> Quoting "Joe Subich, W4TV" <lists at subich.com>:
>>
>>>
>>> Unless the monobanders have been designed to operate in a stack
>>> ("Christmas tree"), stacking them as closely as will be needed to
>>> stay within your 5m mast will certainly reduce their performance.
>>>
>>> If the monobanders have been optimized to work in a stack, use the
>>> spacing for which they were designed.
>>>
>>> 73,
>>>
>>>     ... Joe, W4TV
>>>
>>>
>>> On 2014-12-11 9:16 AM, Fuad Arnautovic wrote:
>>>> Hi all
>>>>
>>>> I need advice from some more experienced with stacking about possible setup.
>>>>
>>>> Have self-standing tower abt 18 mtr, mast 50 mm (2") 5-6 metres long
>>>>
>>>> Antennas are three monoband yagis as follows
>>>>
>>>> 20m 4el 9,5m boom
>>>> 15m 5el 9,6m boom
>>>> 10m 5el 7,6m boom
>>>>
>>>> Does it "Christmas tree" setup working well with this monobanders?
>>>> What is your recommendation for vertical spacing between? Does 2"
>>>> mast is strong enough to support all them.
>>>>
>>>> I would install lowest antenna for 20m then 15m and on the top 10m
>>>>
>>>> I know that is compromise against performance and radiation
>>>> pattern, but actually cannot install another tower
>>>>
>>>> Please help
>>>>
>>>> Thanks in advance
>>>> Fudo, E73CQ
>>>> _______________________________________________
>>>>
>>>>
>>>>
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