[TowerTalk] adding a 40m dipole to a TH-11DX

[K4RO Kirk Pickering]

The link below describes how I implemented the N4KG boom matching idea 
on a Mosley PRO-57A. I am still using the antenna successfully today. As 
long the the outer-most elements of the Yagi are electrically connected 
to the boom (to act as capacity hats) the omega match should work fine 
with most 24 foot boom tri-banders.

http://www.k4ro.net/tcg/pix/40boom.html

--Kirk K4RO


On 3/8/2016 10:03 PM, Mitch wrote:
> All,
>
>                  I will be putting up a tower in the next few months, and an
> finalizing the antenna system I want to put on top. I already have a TH-11DX
> that will be the main antenna for the upper HF bands, and dipoles for most
> everything else. I found a design on the net by K6IF that I am considering
> constructing for 40m. I have a scrap TH-6DX that I can scavenge enough
> material to build the dipole. I plan on feeding it separately from the
> TH-11DX. I do not want to mount the 40m dipole on the mast above or below
> the TH-11DX.  What I am currently considering is lengthing the TH-11DX boom
> about 4 ft to the rear, and mounting the 40M dipole on the boom extension
> behind the 20m reflector. Of course, I will have to move the mast mounting
> point to the rear approx 2ft and extend the truss cables to take the extra
> length. Anyway, that is the current plan. I have searched the archives, and
> have not found any posts in regards to this type of setup with this HF beam.
> I am concerned about interference to the 15m portion of the TH-11DX. I think
> the 12m driven element should "act" as a reflector and shield the 15m
> section from the 40m dipole. I am not very well versed in antenna modeling,
> and have not been able to find a NEC profile for the TH-11DX that I could
> play with. So, with all of that said, is there any reason this should not
> work? I look forward to hearing what the group has to say
>
>
>
> Thanks
>
> Mitch KJ7JA
>
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