Thanks for all the input received.
In short it seems like lifting the coil would not do much difference.
Raising/increasing the angle of the top loading spokes might be the better
option.
Then of course moving the antenna to the water and improving the radials
including some going into the water should make the most improvement.
Unfortunately I can not move the antenna much more. Putting it on the beach
would be hassle as it had to come down every morning and go up again in the
evening. To much activity on the beach in daytime :)
I will see what I can do with the top loading spokes. The wind has changed
today, it might help or it might not. Thanks again for all the input received
on the reflector and in private.
73 from the Maldives de Björn,
SM0MDG
8Q7BM
SE0X
On 29 Jan 2014, at 12:47, Björn SM0MDG <bjorn@sm0mdg.com> wrote:
> Here are some question for anyone with more tech skills than me;
>
> My compromise vertical at 8Q7BM is made of thin wire attached to a DX-Wire 15
> meter glass fibre pole. The vertical wire goes all the way up, but as the
> pole’s top sections are very thin/weak the three top loading spokes (each 12
> meter long) are attached at about 13 meter. The antenna has a 1/4 elevate
> radial towards the water at 2-3 meter height. The whole structure is within
> 1/4 wave of the water line.
>
> The antenna is self resonant at 2.2 MHz and I use a coil wound on a water
> bottle to bring it down to 1.8. The coil appears to be about 8-10 uH
> according to online calculators.
>
> My questions are;
>
> How much I can improve by moving the coil up. What improvement should I
> expect if center loading at about 7 meter? How about moving the coil all the
> way up to the top loading spokes? Is it worth the effort? (the pole won’t
> support much up there).
>
> My top loading spokes are sloping more than the recommended angle. According
> to the ON4UN Low Band book I got the impression that the difference should be
> minimal when close to salt water. I have tried to slope them less, but easily
> get in trouble with the weak pole in the wind. And there are pats to the
> beach every where so options are few.
>
> Which one of the two above actions would be the most beneficial? Move the
> loading coil higher up or rearrange the top loading spokes for a better angle?
>
>
> 73 de Björn,
> SM0MDG
> 8Q7BM
> SE0X
>
>
>
>
>
>
>
>
>
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